Category: Opinions

  • Considering GPS III in light of a PNT wager

    Considering GPS III in light of a PNT wager

    It was not a big wager as wagers go, at least not in monetary value, but the underlying premise of the wager spoke volumes. It all began innocently enough in 2005 when the first test, or proof of concept, Galileo satellite known as GIOVE-A was launched.

    In March of that year, a group of PNT experts made a simple wager that there will be:

    • 10 or fewer operational Galileo satellites by 12/31/15

    or

    • 11 or more operational Galileo satellites by 12/31/15
    Galileo's GIOVE-A retired in June 2012.
    Galileo’s GIOVE-A retired in June 2012.

    About 20 PNT experts took the bet, evenly divided on both sides, which essentially said that given that the first test (GIOVE) Galileo satellites were launched in 2005 and 2008 respectively, surely there would be at least 10 operational satellites on orbit or about one per year by 2015.

    The stakes were modest, but as I said, the import of the faith (or lack of faith) in the European Union and its ability and understanding of the difficulties involved in the Galileo endeavor spoke volumes. As the chief scientist at Air Force Space Command stated at the time, “This is rocket science; this is hard.”

    Chutzpah and/or naïveté

    But the Europeans refused to believe it was a very hard problem. Indeed, after the second GIOVE launch, GIOVE-B in 2008, the European ministers announced, with incredible chutzpah and/or naïveté, that the Galileo constellation would be fully operational (24 fully operational on-orbit satellites) by 2013.

    Of course, nothing of the sort has happened. Following the in-orbit validation (IOV) satellites, the first operational satellite launch did not occur until October 2011, almost six years later.

    As of May 2016, there were 12 operational Galileo satellites on orbit along with two in early orbit or checkout stages — a far cry from the predicted 24 operational satellites. This is not a criticism of the Galileo system; rather, a validation of those who took the pessimistic side of the wager and of the chief scientist who clearly stated the obvious: this is indeed, as a popular euphemism states, a DARPA hard problem.

    So the Europeans have been going about this PNT business since the initial decision to proceed in 2003 — 13 years. The United States has been producing and launching GPS satellites continuously since the first test launch of a NAVSTAR satellite in 1977 (39 years), with a continuously fully operational system (FOC) since 1995 (21 years), and guess what? It is still a hard problem. No one denies that. Which brings us to GPS III.

    GPS III Update

    Since the United States — specifically the United States Air Force (USAF) — has been in the space-borne PNT business longer than any other nation, you would think we would have this down by now. But it is still a hard problem with, fortunately, a long string of successes and very few (only two) failures.

    To date, the U.S. government has launched a total of 72 GPS satellites. There are 31 active operational GPS SVs (satellite vehicles) on orbit, with seven additional in residual or test status; 32 have been retired into a parking orbit where they will not interfere with the operational constellation. That equates to 1.85 GPS satellites launched per year on average, or one every 6.5 months — an enviable record, failures and all.

    Plus, there are GPS IIA satellites still on orbit that have been there for more than 22 years. Not bad for a satellite built to last (contracted service life) for 7.5 years.

    Amazingly, the payloads on every GPS satellite to date were built, in part, in partnership with or completely by one company, now known as Harris, nee Exelis, nee ITT. Of course, the complexity of the payloads being built by Harris for the GPS III satellites is a far cry from the payloads built in 1975 for launch in 1977. According to GPS III program manager and VP Mark Stewart and his cohorts at Lockheed Martin (LMCO), the aerospace company building the GPS III satellites, GPS III

    “…will deliver three times better accuracy, provide up to eight times improved anti-jamming capabilities and extend spacecraft life to 15 years [ed. contracted life], 25 percent longer than the [ed. latest family of satellites on orbit today]. GPS III’s new L1C civil signal … will make it the first GPS satellite to be interoperable with other international global navigation satellite systems.”

    While many of you may look upon that LMCO statement as marketing hype, in fact it is a rather incredible prophesy. To a PNT expert it translates to: almost all GPS users globally will have sub-meter level positional accuracy from a group of signals that will rarely if ever be completely jammed, from an SV with a projected lifetime of 30 years that has more signals and greater signal strength, flexibility and interoperability than ever before. By the numbers GPS is still, far and away, the world’s gold standard.

    So exactly where are we in relation to a launch of the first evolutionary GPS III satellite? After all, the last IIF launch, number 12 in the series, built by Boeing, occurred in February, so by the law of averages we should have the first GPS III launch later this month. That is not going to happen, but then what is a few months among friends when iterated over 39 years?

    Currently the first GPS III launch date, according to the USAF, is scheduled for May 2017. All indications are the government is on track to meet that date with, interestingly enough, the availability of a suitable launch vehicle being the LIMFAC (limiting factor), not the availability of an GPS III SV to launch.

    SV 01 in testing at Lockheed Martin's Denver facility. (Photo: LMCO)
    SV 01 in testing at Lockheed Martin’s Denver facility. (Photo: LMCO)

    According to my sources, GPS III SV-01 is fully integrated, has completed all environmental testing and is essentially ready to ship to Cape Canaveral,. It would be available for launch (AFL) sometime before the end of the calendar year if there were a launch vehicle, a ground control system and range availability.

    GPS III SV-02 will undergo full integration (“core-mating”) completion sometime this fall and — following successful completion of its environmental tests — should certainly be AFL in 2017.

    The complete navigation panel (from Harris) for GPS III SV-03 should arrive in the LMCO Denver facility early next year. Providing the vehicle stays on track through testing, it should be AFL in 2018.

    The government has yet to complete the contract award process for GPS III vehicles SV-09 and SV-10 to LMCO, but I am assured the award is imminent.

    My sources confirm that Harris is continuing to pump money, expertise and technology into the GPS III payload development process, a manufacturing tour de force, and the company should be back on schedule early next year.

    As for OCX, the future GPS Ground Control Segment, that is another tale for another time. For all other GPS III segments, all in all it is a positive message for development and deployment. Which is an admirable feat — after all, it is rocket science!

    By the way, the Galileo wager is open to interpretation. There were certainly more than 10 Galileo platforms on orbit on the last day of December 2015, but only nine of them were operational at the time. Both sides are claiming victory. What a surprise!

    A product to save your hearing

    The EB15LE with Hearing Defenders with accessories. (Photo: ERI)
    The EB15LE with Hearing Defenders with accessories. (Photo: ERI)

    Before I close, I want to mention a product I have tested as extensively as I can in a limited environment. I agreed to test this non-GPS product because of all the emails and letters I receive concerning tinnitus and how it negatively affects our warfighters. Several emails make clear the necessity and criticality of a good sight picture or display for GPS guidance, especially where exfiltration is concerned.

    When warfighters or law enforcement officers are suffering the ill effects of extremely loud noises, it is often disorienting. Much like the effects of a flash-bang device, a victim can lose his bearings and needs to have a clear visual of how to exit the threat environment.

    The best solution would be not to suffer the devastating effects of the loud noises in the first place. This is where a company named Etymotic Research Incorporated (ERI) comes into play. ERI has developed electronic hearing protection for law enforcement officers and military users.

    The version I tested was designated the EB15 for law enforcement. It functioned well as electronic hearing protection and amplification where needed. The device is essentially an electronic hearing aid that amplifies natural or quiet sounds up to five times, and a hearing defender that electronically blocks loud, harmful sounds by up to 25 decibels.

    While I was not able to test the hearing defenders in actual combat, the testing I did perform demonstrated that the EB15-LE is an impressive product with a plethora of earplugs for various noisy environments that may help save a user’s hearing. Our warfighters and law-enforcement officers deserve the best technology available, especially if it helps them retain their orientation in a dangerous environment and saves their hearing.

    Until next time, happy navigating, and remember: GPS is brought to you free of charge courtesy of the USAF.

  • Expert Opinions: OEM R&D budget for mitigation of jamming

    Q: What percent of a GNSS designer or manufacturer’s R&D budget should be devoted to mitigation of jamming?

    MIchael Ritter, President & CEO, Novatel Inc.
    MIchael Ritter, President & CEO, Novatel Inc.

    A: Solving for jamming, intentional or unintentional, in the design of any GNSS technology platform is no longer an option. How much any one company spends is largely a function of how much is spent on engineering overall and of how much has already been invested upfront on jamming mitigation. The required level of jamming resistance of any PNT solution also depends very much on the particular application, which in turn influences the budget allocated.


    Jeff Martin, Director, GPS/GNSS Sales,  Spirent Federal
    Jeff Martin, Director GPS/GNSS Sales,
    Spirent Federal

    A: GNSS jamming is a growing concern, and an assessment of risks and an element of testing against the most applicable real world threats should be included as part of every developer’s engineering process. Spirent has decades of experience in providing test equipment and services to engineers working to understand and mitigate jamming threats. We have seen increased investment by designers and integrators of PNT systems that are driven to provide robust/resilient solutions to their customers.


    Andrey Soloviev, Principal, Qunav
    Andrey Soloviev, Principal, Qunav

    A: While some receivers already incorporate jamming protection (e.g., CW excision), more sophisticated methods (for example, against broad-band jamming and spoofing) should be incorporated into perspective products. The percentage of R&D budget depends on a line of business. For manufactures pursuing applications such as military and critical infrastructure, the number can be as high as 50 percent. For many civilian applications a potential impact of jamming is less damaging. Yet, from 10 percent to 20 percent should be still allocated.

  • Pokémon GO: Location-based app leads to accidents

    We have to stop. It’s a Jigglypuff!

    Common sense tells us not to hold a smartphone while driving. But a new game is so addicting, it’s causing people to forget that rule.

    Released July 6 for both Android and iOS, Pokémon GO instantly became the top free app and the top grossing app on Apple’s App Store, shattering social media records and shooting Nintendo stock through the roof. And it hasn’t even been introduced in Europe and Asia yet. (Japan, of course, is the birthplace of Pokémon.)

    The game uses augmented reality to place the coveted virtual monsters (Pokémon) into real-world locations, so users have to travel to add to their collections.

    However, much like in the early days of GPS navigation, when people ended up driving down railroad tracks or into ponds, the Pokémon GO app has led to accidents. Some users are playing the location-based game from inside their vehicles, stopping suddenly, while pedestrians are staring at device screens as they walk through busy cities, sometimes onto private property.

    In the first week:

    • A 28-year-old Auburn, New York, driver ran his vehicle off the road and crashed into a tree.
    • A Massachusetts man woke up to a garden full of wandering Pokémon players after his home  — once a church — had been marked as a “gym” (multi-player battleground).
    • A group of Missouri teenagers were arrested for armed robbery after allegedly using the app to anticipate secluded locations for holdups.

    Police departments around the country are warning that anyone caught using the app while driving or jaywalking could end up with a hefty fine.

    But there’s an upside, too. Gamers are going outside, getting exercise and making new social connections.

    And, apparently, helping police. One 19-year-old Wyoming woman, on a quest to catch a Pokémon from a natural water resource, instead discovered a dead body floating in the Big Wind River.

  • NGA hackathon creates new tools for disaster response

    Hackers-2-GEOINT-WThe National Geospatial-Intelligence Agency (NGA), GEO Huntsville and AEgis Technologies hosted a two-day inaugural hackathon May 2-3 at Cummings Research Park in Huntsville, Alabama, dubbed #GEOHackHSV.

    Most of you are familiar with hackathons, but this one was focused on geospatial solutions for first responders with NGA’s GeoQ as a foundation. The goal was to hack unclassified geospatial datasets and open-source tools to build effective solutions for disaster response and recovery.

    The foundation – NGA’s GeoQ

    Ray Bauer, who heads up the NGA GeoQ effort, was the keynote speaker. He explained how GeoQ meets the goals set by former NGA Director Latisha Long and current Director Robert Cardillo to take advantage of open-source data, applications and most important talent. Ray explained how the growing complexity of the GEOINT world forces NGA to take advantage of every geospatial resource available while keeping their classified work secure.

    Ray stated NGA’s hackathon goals, specifically:

    “We are interested in working with participants to identify and create new, interactive and efficient ways of reading, disseminating and analyzing tons of data from disparate systems. We highly encourage leveraging open-source tools and other software solutions participants bring to the table. This hackathon is not just for those entrenched in the geo world! We’re interested in everything from new mapping interfaces, mobile solutions, lightweight and portable information dashboards, hardware integrations with commercial off-the-shelf tools like sensors and UAVs, and everything in between!

    “The intent of this event is to think outside the box and employ new tools and alternative open-source data to more efficiently and accurately send the most relevant data to emergency responders quickly. Currently there are dozens of data sets that make it difficult to quickly search and integrate into a common operational environment, particularly across the sectors: firefighter, police, hospital, dispatcher, HEMSI, air evacuation, utilities, Department of Transportation, etc. How do we share information among these groups during disaster situations such as tornadoes, hurricanes, shootings, flooding, significant traffic events, chemical spills and other potentially catastrophic events?”

    For those of you not familiar with GeoQ, there is an excellent overview produced by NGA that is on Youtube.

    GeoHuntsville hackathon goals

    Hackers-1-GEOINT-WThe pre-event announcements listed the following goal.

    Combine commercial and proprietary hardware and software solutions to create unique concepts/solutions. Specifically:

    • Solve disparate data problems among current open source data sets (i.e. overlaying multiple shape files with real-time data from multiple sources such as emergency responder software, sensors in the field, social media, e.g.).
    • Recreate more aesthetically appealing user interfaces considering numerous data sets — to include mobile solutions.
    • Suggest new solutions leveraging a subset of currently available data. (Use the data we give you, use the data you bring, use the data we don’t know about — and create a solution to a problem we don’t know exists.)
    • Integrate new solutions or disparate data into open source tools, like GeoQ.
    • Identify ways to more efficiently and accurately receive and analyze updates from the field. (This could be anything from a tool an emergency responder uses or social media resources.)
    • Come up with a way to disseminate critical information across agencies and geographic locations.

    First responder involvement

    The aspect of this hackaton that was particularly valuable was the direct involvement of numerous Huntsville first responders. Policemen and firemen were able to explain their difficulties and needs face to face with the programmers and engineers who were participating in the hackathon, so the participants were not operating in a vacuum. See my interview with the Huntsville fire chief.

    Fueled with sodas, chips and snacks, the hackers worked overnight to accomplish the goals. At stake were three prizes, including a top prize of $1,000. The prizes were not huge, but they provided some incentive including bragging rights.

    Although some results were similar to existing applications, the different approaches were still very impressive for a two-day event. You may find one or two applications worth your further investigation for integration in your systems.

    The teams

    Mobile Damage Assessment

    Micah Cleveland and Larry Wilbourn provided firefighters with a way to directly report the status of damaged structures or casualties and triage via a smartphone.

    Situational Awareness

    The team of Larry Mason, Tyler Hughes and Michael Carroll built an application displaying real-time locations of all emergency vehicles and the display of preplan floor plans and imagery to show details such as electric and gas cut offs.

    Virtual Reality GIS Display

    Jason Rade and Jason Nofki demonstrated their system of displaying GIS data and imagery using a virtual reality headset. They indicated that the next step was to display the data as augmented reality.

    OpenSensorHub

    Steve Jones demonstrated a system to display Internet of Things (IoT) devices as live links on a map to display data, imagery and video from those sources. (Steve participated in the event, but did not enter into the competition.)

    WEBEOC data to current devices

    Two team members worked a problem proposed by Madison County Emergency Management Agency. They read legacy format WEBEOC data and converted the information into more modern device data structures.

    And the winners are…

    • First Place: Mobile Damage Assessment
    • Second Place: WEBEOC data to current devices
    • Third Place: a tie between Situational Awareness and Virtual Reality GIS Display

    A few gems developed at the hackathon may be useful with your applications effort. If you need additional information regarding the hackathon and participants, contact Chris Johnson of GeoHuntsville at [email protected].

  • Establishing orthometric heights using GNSS — Part 8

    Establishing orthometric heights using GNSS — Part 8

    Upcoming Survey Scene newsletters will carry additional columns in this series.


    Basic procedures and tools for determining valid published NAVD 88 GNSS-derived orthometric heights for constraints

    These columns have provided the reader with basic concepts, routines and procedures for understanding, analyzing, evaluating and estimating GNSS-derived ellipsoid and orthometric heights.

    In my last column, Part 7 (June 2016), we analyzed the changes in adjusted heights due to different leveling-derived NAVD 88 height constraints and compared the results with the published NAVD 88 leveling-derived orthometric heights. My column demonstrated how every constraint has an influence on the final set of adjusted heights.

    As mentioned in previous columns, when incorporating new geodetic data into the National Spatial Reference System (NSRS), it is important to maintain consistency between neighboring stations. If the station has moved since the last time its height was established then not constraining the published value and superseding the height is the appropriate action to take. As I emphasized in Part 6 (April 2016), if the difference is not due to movement but due to some other reason such as the results of a previous adjustment distribution correction then superseding the height may not be the appropriate action to take. In Part 6, we looked at the network design of the NAVD 88 project and estimated the potential NAVD 88 distribution correction between two benchmarks involved in the original NAVD 88 general adjustment. It was also mentioned in the last newsletter that all of the analysis and recommendations have been based on using the latest scientific geoid model xGeoid15b.

    However, in practice, GNSS-derived orthometric heights are incorporated into the NAVD 88 using the latest hybrid geoid model, i.e., GEOID12B. I recommend first performing the analysis using the scientific geoid model because the hybrid geoid model has been warped to be consistent with the published NAVD 88 values. This was described in detail in my October 2015 newsletter. The analysis using the scientific geoid should be included in the project report especially if the user finds significant differences between the results using the two different geoid models. In my last column, I stated that “maintaining consistency between closely spaced stations is extremely important when incorporating data into an existing network. Based on the information so far and the results using GEOID12B, I would not recommend constraining the published NAVD 88 heights of stations PHANIEL and PLAZA in the final NAVD 88 GNSS-derived orthometric height adjustment. These two stations resulted in significant changes in relative adjusted heights when they were constrained. (See Part 6.)”

    It was also noted in a previous column (Part 5, February 2016) that 10 of the 2015 GNSS Rowan County Height Modernization project’s stations have published NAVD 88 GNSS-derived orthometric heights. These station are denoted as Height Modernization stations and are important because they are on the edge of the network where there’s a void of published NAVD 88 leveling-derived orthometric heights. In this newsletter, for these 10 stations we will look at the differences between their published NAVD 88 heights and their adjusted GNSS-derived orthometric heights from the Rowan County project.

    First, we need to briefly look at one of the leveling-derived stations — Station PLAZA — that was identified as a potential outlier in Part 7. In that column, I provided the following information about station PLAZA:

    The geodetic data and information for station PLAZA is listed below:

    • As described in Part 6 (April 2016), station PLAZA and station FIFTH have a large relative difference between the adjusted GNSS-derived orthometric height and the published NAVD 88 orthometric height value (-3.2 cm);
    • Four other stations in the vicinity have small relative differences between the adjusted GNSS-derived orthometric heights and the published NAVD 88 orthometric heights values, 37 DRD (0.6 cm), Midtown (-0.1 cm), Midway (1.0 cm), and J 181 (1.1 cm) — indicating a problem with station PLAZA;
    • Station FIFTH and PLAZA are only 400 meters apart, and their adjusted heights were established in two different adjustments: station FIFTH was leveled in 2013 (adjustment date of March 2015) and station PLAZA was leveled to in 1989 (adjustment date of September 1997) — indicating a potential inconsistency between adjustments;
    • PLAZA’s datasheet states that “the station was recovered as described in 2012 except the area between the curb and sidewalk has been filled with concrete. Mark is now part of the sidewalk but does not appear to have been disturbed.”

    Based on the available information to date, I would not recommend constraining the published height of station PLAZA in the final adjustment. Once again, this station’s published height should not be superseded by the GNSS project until new leveling has been performed between station FIFTH and PLAZA.

    As I mentioned, Station PLAZA’s published height should not be superseded by the GNSS project until new leveling has been performed between station FIFTH and PLAZA. Well, ask and you will receive. Gary Thompson, the director of the North Carolina Geodetic Survey, had one of his field crews, which was in the area, relevel the section between station FIFTH and PLAZA. The newly leveled results changed the leveling-derived height of PLAZA relative to FIFTH by 3.5 cm. The new leveling-derived orthometric height of PLAZA now agrees with the GNSS-derived orthometric height to within a centimeter.

    This means that the published height of PLAZA should not be constrained in the final adjustment and should be superseded by the GNSS-derived orthometric height. If the leveling data is submitted to NGS for inclusion into the NAVD 88, then the NAVD 88 height resulting from the new leveling data should be constrained in the final adjustment.

    Now, let’s look at the 2015 GNSS Rowan County Height Modernization project’s stations that have published NAVD 88 GNSS-derived orthometric heights. The user can identify stations that have been established following NGS Height Modernization procedures by looking at NGS datasheets. The datasheets for Height Modernization stations have the following statement at the top of the datasheet: “This is a Height Modernization Survey Station.” In addition to that statement, the NAVD 88 orthometric height is published to the centimeter level with the attribute code of “GPS OBS.” (See the example titled “Excerpt from the NGS Datasheet for Station GOODMAN.)

    Excerpt from the NGS Datasheet for Station GOODMAN

    1 National Geodetic Survey, Retrieval Date = JULY 2, 2016
    DL9977 ***********************************************************************
    DL9977 HT_MOD – This is a Height Modernization Survey Station.
    DL9977 DESIGNATION – GOODMAN
    DL9977 PID – DL9977
    DL9977 STATE/COUNTY- NC/STANLY
    DL9977 COUNTRY – US
    DL9977 USGS QUAD – GOLD HILL (1983)
    DL9977
    DL9977 *CURRENT SURVEY CONTROL
    DL9977 ______________________________________________________________________
    DL9977* NAD 83(2011) POSITION- 35 30 06.47415(N) 080 15 37.24680(W) ADJUSTED
    DL9977* NAD 83(2011) ELLIP HT- 171.358 (meters) (06/27/12) ADJUSTED
    DL9977* NAD 83(2011) EPOCH – 2010.00
    DL9977* NAVD 88 ORTHO HEIGHT – 201.76 (meters) 661.9 (feet) GPS OBS
    DL9977 ______________________________________________________________________
    DL9977 NAVD 88 orthometric height was determined with geoid model GEOID09
    DL9977 GEOID HEIGHT – -30.377 (meters) GEOID09
    DL9977 GEOID HEIGHT – -30.402 (meters) GEOID12B
    DL9977 NAD 83(2011) X – 879,427.184 (meters) COMP
    DL9977 NAD 83(2011) Y – -5,123,507.841 (meters) COMP
    DL9977 NAD 83(2011) Z – 3,683,429.929 (meters) COMP
    DL9977 LAPLACE CORR – 1.70 (seconds) DEFLEC12B
    DL9977
    DL9977 Network accuracy estimates per FGDC Geospatial Positioning Accuracy
    DL9977 Standards:
    DL9977 FGDC (95% conf, cm) Standard deviation (cm) CorrNE
    DL9977 Horiz Ellip SD_N SD_E SD_h (unitless)
    DL9977 ——————————————————————-
    DL9977 NETWORK 0.41 0.80 0.18 0.15 0.41 -0.01103221
    DL9977 ——————————————————————-
    DL9977 Click here for local accuracies and other accuracy information.
    DL9977

    The procedures for analyzing the published NAVD 88 GNSS-derived orthometric heights are the same as those used to analyze the NAVD 88 leveling-derived orthometric heights. These procedures and routines have been documented in my previous columns. There is, however, one major difference between incorporating new leveling data into NAVD 88 and incorporating new GNSS data into NAVD 88. That is, when a station gets superseded in a leveling network adjustment due to previous adjustment distribution corrections, to maintain consistency the older leveling data in the area are readjusted to be consistent with the newly observed leveling data and latest published adjusted heights.

    An adjustment distribution correction from the NAVD 88 general adjustment was discussed in the Part 7 (See Figure 6, “An Example of an Estimate of the NAVD 88 Distribution Correction Between two Stations Established with Old Leveling Data and Large Loops.”). So, what’s the difference?

    Both NAVD88 leveling-derived orthometric heights and GNSS-derived orthometric heights are based on adjustments constraining NAVD 88 published orthometric heights. However, GNSS-derived orthometric heights are also computed using the latest NGS hybrid geoid model. If a station’s GNSS-derived orthometric height gets superseded, the previous GNSS data are not readjusted to be consistent with the latest observations and published heights. Once again, if the station physically moved then superseding the height is the appropriate action and there is no requirement to readjust the older GNSS data.

    However, if the station did not physically move then the new published height may be inconsistent with its neighboring stations. I’m not saying that this is right or wrong, I’m only mentioning it so the user considers this information in their analysis.

    The procedures outlined in NGS’ NGS 59 document, which was discussed in Part 5, were developed to minimize the effect due to different geoid models and superseded heights. (See excerpt titled “Four Basic Control Requirements for Estimating GNSS-Derived Orthometric Heights.”) The requirements include surrounding the project with valid NAVD 88 benchmarks and, if necessary, enlarging the project area to occupy enough leveling-derived benchmarks. The intent of these requirements are to help control any small relative differences between previously published hybrid geoid models. It should be noted that some of the latest hybrid geoid models are significantly different the older hybrid geoid models.

    Therefore, when comparing a project’s adjusted heights with published NAVD 88 GNSS-derived orthometric heights, the user needs to consider which hybrid geoid model was used to establish the published GNSS-derived orthometric height. The NGS datasheet provides the hybrid geoid model and geoid height value used to establish the height. This was highlighted on the datasheet for station GOODMAN (see the example titled “Excerpt From the NGS Datasheet for Station GOODMAN). The statement NAVD 88 orthometric height was determined with geoid model GEOID09 means that station GOODMAN’s GNSS-derived orthometric height was established in a GNSS project using the hybrid geoid model GEOID09. The question is, what’s the difference between GEOID09 and the latest hybrid model?

    The datasheet provides the hybrid geoid model value used to establish the height (in this example, GEOID09 = -30.377 m) as well as the latest hybrid geoid model value (in this example, GEOID12B = -30.402 m). Based on station GOODMAN’s published datasheet, the difference is only 2.5 cm. This difference may be much larger in the mountains of North Carolina.

    Four Basic Control Requirements
    for Estimating GNSS-Derived Orthometric Heights:

    Requirement 1: GNSS-occupy stations with valid NAVD 88 orthometric heights; stations should be evenly distributed throughout project.

    Requirement 2: For project areas less than 20 km on a side, surround project with valid NAVD 88 benchmarks, i.e., minimum number of stations is four; one in each corner of project. [NOTE: The user may have to enlarge the project area to occupy enough benchmarks, even if the project area extends beyond the original area of interest.]

    Requirement 3: For project areas greater than 20 km on a side, keep distances between valid GNSS-occupied NAVD 88 benchmarks to less than 20 km.

    Requirement 4: For projects located in mountainous regions, occupy valid benchmarks at the base and summit of mountains, even if the distance is less than 20 km.

    Station BLACK BEAR, located in the mountains near Asheville, North Carolina, is an example of a significant difference between GEOID09 and GEOID12B; the difference is -14.9 cm. (See the example titled “Excerpt from the NGS Datasheet for Station BLACK BEAR.) This may not be a problem if all stations in the area are effected by the same difference but that’s not the case in this area.

    Station BUCK is a nearby station (about 11 km away from BLACK BEAR) and according to the NGS database “mark_source option”, stations BLACK BEAR and BUCK were involved in the same GNSS project so their GNSS-derived orthometric heights most likely were established in the same adjustment project. [NOTE: The use of the “mark_source” option of the NGS datasheet was described in Part 7.] The GEOID09 and GEOID12B difference at station BUCK is 1.0 cm. The relative difference in hybrid geoid models between stations BLACK BEAR and BUCK is almost 16 cm.

    Excerpt from the NGS Datasheet for Station BLACK BEAR

    PROGRAM = datasheet95, VERSION = 8.9
    1 National Geodetic Survey, Retrieval Date = JULY 26, 2016
    DM2549 ***********************************************************************
    DM2549 HT_MOD – This is a Height Modernization Survey Station.
    DM2549 DESIGNATION – BLACK BEAR
    DM2549 PID – DM2549
    DM2549 STATE/COUNTY- NC/YANCEY
    DM2549 COUNTRY – US
    DM2549 USGS QUAD – MT MITCHELL (1946)
    DM2549
    DM2549 *CURRENT SURVEY CONTROL
    DM2549 ______________________________________________________________________
    DM2549* NAD 83(2011) POSITION- 35 46 00.04321(N) 082 15 54.04248(W) ADJUSTED
    DM2549* NAD 83(2011) ELLIP HT- 1974.465 (meters) (06/27/12) ADJUSTED
    DM2549* NAD 83(2011) EPOCH – 2010.00
    DM2549* NAVD 88 ORTHO HEIGHT – 2004.48 (meters) 6576.4 (feet) GPS OBS
    DM2549 ______________________________________________________________________
    DM2549 NAVD 88 orthometric height was determined with geoid model GEOID09
    DM2549 GEOID HEIGHT – -29.990 (meters) GEOID09
    DM2549 GEOID HEIGHT – -29.841 (meters) GEOID12B
    DM2549 NAD 83(2011) X – 697,556.510 (meters) COMP
    DM2549 NAD 83(2011) Y – -5,135,618.055 (meters) COMP
    DM2549 NAD 83(2011) Z – 3,708,370.482 (meters) COMP
    DM2549 LAPLACE CORR – -6.14 (seconds) DEFLEC12B
    DM2549
    DM2549 Network accuracy estimates per FGDC Geospatial Positioning Accuracy
    DM2549 Standards:
    DM2549 FGDC (95% conf, cm) Standard deviation (cm) CorrNE
    DM2549 Horiz Ellip SD_N SD_E SD_h (unitless)
    DM2549 ——————————————————————-
    DM2549 NETWORK 0.47 0.86 0.21 0.17 0.44 -0.05699591
    DM2549 ——————————————————————-
    DM2549 Click here for local accuracies and other accuracy information.
    DM2549

    chart

    Figure 1 is a contour plot of the differences between GEOID12A and GEOID09 in the area surrounding stations BLACK BEAR and BUCK. [NOTE: The ESRI raster plots are based on GEOID12A not GEOID12B. GEOID12A is identical to GEOID12B everywhere, except in Puerto Rico and Virgin Island region. Therefore, in North Carolina, GEOID12A is equivalent to GEOID12B.] Looking at the plot it is obvious that there is a significant difference between the two hybrid geoid models in this region of North Carolina. What does this mean to someone performing a new GNSS-derived orthometric height adjustment in the area? If they occupied station BLACK BEAR and compared their adjusted GNSS-derived orthometric height using GEOID12B to the NAVD 88 published GNSS-derived orthometric height that was established using GEOID09, they most likely will get a large residual due to the difference between the two hybrid geoid models. As previously mentioned in this newsletter, NGS’ NGS 59 guidelines were developed to minimize the effects of different hybrid geoid models, but in these extreme cases the procedures may not have been able to minimize the total effect. It is important for the user to understand the differences between the various published hybrid models and experimental geoid models being developed by NGS. This topic was discussed in detail in the October 2015 newsletter.

    Figure-1
    Figure 1. A contour plot of the differences between GEOID12A and GEOID09 in the area surrounding stations BLACK BEAR and BUCK.

    Now, let’s look at the published NAVD 88 GNSS-derived orthometric heights occupied in the Rowan County Height Modernization project. Table 1 is a list of the stations occupied in the Rowan County project that have published NAVD 88 GNSS-derived orthometric heights. The table provides the hybrid geoid model value used to establish the published NAVD 88 height as well as the latest hybrid geoid model value, GEOID12B. Figure 2 is a contour plot of the differences between the GEOID12A and GEOID09 in the Rowan County Height Modernization project area. Looking at the plot, the user can see that most of the differences are all less than 3 cm between GEOID12A and GEOID09 in the Rowan County Project area.

    Figure-2
    Figure 2. A contour Plot of the differences between GEOID12A and GEOID09 in the Rowan County Height Modernization project area.

    Table1

    As we can see from Table 1, all of the differences between the two hybrid geoid models are less than or equal to 2.5 cm. (See highlighted rows and column in Table 1.)

    Figure 2 plots the adjusted GNSS-derived orthometric height (using GEOID12B) from a minimally constrained adjustment minus the published NAVD 88 GNSS-derived orthometric heights. Most of the differences are less than 3 cm which for some stations could be a result of the difference hybrid geoid models to establish the published GNSS-derived orthometric heights.

    Looking at figure 2, almost all of the differences between the GNSS-derived orthometric heights (using GEOID12B) from the minimum-constraint least squares compared with the published NAVD 88 GNSS-derived orthometric heights are less than 3 cm. No station appears to be an obvious outlier. The fact that all differences except for one are negative is interesting and is worth investigating at a later date. More analysis will need to be performed to understand if this is significant or not. Table 2 provides the adjusted GNSS-derived heights from a minimally constrained adjustment minus the published heights (both ellipsoid and orthometric).

    The last item to look at is a comparison of the adjusted heights from a constrained adjustment where all valid published leveling-derived heights were constrained. Figure 3 and Table 2 provide the constrained adjustment results (where all of leveling-derived published heights except for the 3 suspect heights were constrained) compared with the published NAVD 88 GNSS-derived orthometric heights. All of the differences are less than +/- 2 cm except for station NATHAN which is -2.1 cm. All of the relative differences of closely-spaced stations are less than 2 cm and most are less than 1 cm. This means constraining these stations should not adversely influence the unconstrained stations. Note that after constraining the published NAVD 88 leveling-derived heights, the negative bias is gone but the differences do not appear to be random. That is, the northern stations are all negative and the southern stations are positive (See figure 3).

    Table2

    Figure 3. A plot of the constrained adjustment results (where all of leveling-derived published heights except for the 3 suspect heights were constrained) compared with the published NAVD 88 GNSS-derived orthometric heights.
    Figure 3. A plot of the constrained adjustment results (where all of leveling-derived published heights except for the 3 suspect heights were constrained) compared with the published NAVD 88 GNSS-derived orthometric heights.

    These newsletters have focused on procedures and routines for establishing GNSS-derived orthometric heights. There are many ways to analyze and investigate GNSS data and adjustment results. I have provided some basic concepts that I believe are important for users to understand. The selection of constraints is a very important part of establishing accurate and consistent NAVD 88 GNSS-derived orthometric heights. It is just as important to document all decisions and results so others know how the published heights were established. NGS has a prescribed set of data and information that are required when submitted data for inclusion into the NSRS. This information is available from the NGS website (see section titled “MATERIALS NEEDED TO SUBMIT FOR THE PROJECT” in the document “adjustment_guidelines.pdf.”). We will address submitting the results in future columns.

    In my next column, I will focus on the NGS GPS on BMS (GPSBM) dataset. This is the dataset used to create the hybrid geoid models; I mentioned this in Part 3. As mentioned in Part 3, the hybrid geoid model is designed to fit the published NAVD 88 leveling-derived orthometric heights. This file can be used to identify potential issues in the NAVD 88 network. GNSS users should be familiar with this dataset and how it can be useful to their analysis. My next column will address this topic.

  • Through the looking glass: New perspectives on GNSS

    Three recent publications offer a range of perspectives on GNSS technology, the accompanying industry and its effects on the world we live in. They are rather like surveying the topic through three types of looking glass: a mirror, a microscope and a telescope. I recommend them all.

    From the first listed below (Misra), you may not learn much new about GPS or GNSS, but you’ll experience something like looking at your reflection or reading an encyclopedia entry about yourself. You’ll get a view of of the GPS ecology in this case, as a broad and curious public might. And that is in itself a learning experience. “O wad some Power the giftie gie us / To see oursels as ithers see us!” — Robert Burns. Read it yourself before giving it to someone you know, of almost any age but probably high school or older, who is curious but not necessarily scientific.

    The second book, by Greg Milner, examines the technology and its impact much more closely and at much greater length. With a few dashes of history and generous helpings of current events, it makes the point that GPS is not only changing our lives, but our minds. That can be a scary thought. The book lays out a very rich and fascinating tapestry of interwoven trends, personalities, anecdotes and conjectures. Again, read it yourself before giving it to anyone who …

    The third publication cited here, a white paper by Rolls Royce and colleague companies, is an online resource showing just where the world is headed. It treats only one realm, marine shipping, but it lays out a convincing vision of a future shaped and directed by PNT that can easily be overlaid onto many other forms of transportation and commerce. U.S. Transportation Secretary Anthony Foxx said it recently: autonomous vehicles are coming, whether the world is “ready or not.”

    GPS for Everyone: You Are Here
    by Pratap Misra
    Ganga-Jamuna Press (available on Amazon)

    GPSforEveryone 1By the co-author of one of the core technical references on GPS and a graduate-level engineering text (Global Positioning System: Signals, Measurements, and Performance, ), this large-format, large-print volume takes a beginner’s view. Although Misra says at two junctures, “we learned to solve [such] equations in high school algebra” and “you may remember from calculus,” no math is necessary to take in the overall view and basic facts of satellite navigation concepts.  As the author states, the only prerequisite for this book is curiosity.

    With chapters on Nuts and Bolts, Signals, Math, Relativity, a Tool of Science, Smart Bombs and more, this primer gives a comprehensive overview of just about everything the general user could well afford to know about GPS. The one shortcoming from a public information point of view is that many of the wide-ranging applications and market sectors are given short shrift.  The importance of precise timing and GPS’ role in critical infrastructure get two paragraphs.  A somewhat pejorative chapter on other GNSS labels them all “wannabes” and makes the surprising assertion that “when Putin goes, so could GLONASS.”

    Pinpoint: How GPS Is Changing Technology, Culture, and Our Minds
    by Greg Milner
    W.W. Norton & Co.

    Pinpoint2GPS marks yet another rite of passage with the publication of Pinpoint: a full-length journalistic investigation of its development, personalities, and societal impact, with a diverting assortment of side stories and philosophical illuminations. A technology can be said to have arrived when it receives this manner of broad-market, though rigorous, intelligent, probing treatment. Never mind that every such technology truly arrived long before their books were written.

    This is not a book to give to friends and relations who ask you “How the heck does GPS work?” (For that, see Pratap Misra’s book.) It does spend a bit of time on that subject, a very little bit. Neither is it a history of GPS. Author Greg Milner spends a bit more time on that topic, and his direct sources are impeccable. The major portion of the book is devoted to “contemporary history,” if there is such a thing: the sprawling tentacle-like growth of GPS into many industries and aspects of modern life.

    Milner does not chronicle every one or even a plurality of these diverse fields. One gets the feeling he pretty much followed his journalistic nose into whatever interested him. Sections explore early receiver development, electrical power, financial markets, tracking (both personal and fleet), agriculture with a focus on the sugar beet, auto navigation,   and a few more. Throughout, Milner pushes forward anecdotes — personal recollection of many, many diverse contributors and benefitees, or in a few cases, victims. One chapter bears the title “Death by GPS.”

    He takes long, looping sidetrips that are always interesting, far though they may wander. The most notable case is that of Polynesian cross-Pacific navigation, a mental construct called etak, which takes up, at length, the first chapter of the book. We become aware that possibly what interests Milner most is navigation as a state of mind. He attempts to tie it all together at the end; it doesn’t quite work, but the many questions he raises along the way are certainly worth pondering.

    Two examples, only pages apart. In an investigation of the legality and Constitutional issues of tracking and surveillance by law enforcement, he states: “GPS provides the possibility of omniscience, unlike any previous technology. There is nothing ‘natural’ about using GPS to keep a continuous inventory of the world’s moving parts. It reflects a choice, a conscious application of a neutral technology . . . GPS itself is a blank slate onto which we project our desires.”

    And in a section on marketing: “Stickiness, a term online marketers apply to websites that encourage repeat visits, could also describe how GPS lets us ‘build situational contexts around things and people to create new meanings, associations and stickiness of disparate data. The simplest example is when we use a program like Google Maps to learn about our location, a sticky query that draws in satellite mapping, ground-level photography, and business information.”

    Remote and Autonomous Ships: The Next Steps
    Available online from Rolls Royce and the AAWAAAWA

    The Advanced Autonomous Waterborne Applications Initiative (AAWA) published a white paper in June as part of presentations at the Autonomous Ship Technology Symposium 2016 in Amsterdam. The white paper outlines the Project’s vision of how remote and autonomous shipping will become a reality.

    Oskar Levander, Rolls-Royce Vice President of Innovation – Marine, said “This is happening. It’s not if, it’s when. The technologies needed to make remote and autonomous ships a reality exist. The AAWA project is testing sensor arrays in a range of operating and climatic conditions in Finland and has created a simulated autonomous ship control system which allows the behaviour of the complete communication system to be explored. We will see a remote controlled ship in commercial use by the end of the decade.”

    The AAWA white paper explores the research carried out to date on the business case for autonomous applications, the safety and security implications of designing and operating remotely operated ships, the legal and regulatory dimensions and the existence and readiness of a supplier network to deliver commercially applicable products in the short to medium term.

    Positioning Technologies. The proposed system draws on a range of sensors (see Figure 1) including GPS, inertial, lidar, cameras, short-range radars, and electronic charts. “When combined witha global or local positioning reference such as GNSS, and with wind sensors and inertial measurement units, the ship is able to keep its position even in rough weather conditions,” states the report. “The main question is therefore not whether the implementation of autonomous ship navigation is technically possible, but what is the combination of technologies and methods that provides the level of performance and reliability that is required for practical operation of large vessels, and at a reasonable cost.”

    ProposedMarine

    The white paper draws on a wide range of expertise from academic researchers at some of Finland’s leading universities. Industry input has been provided by leading members of the maritime cluster including Rolls-Royce, Brighthouse NAPA, Deltamarin, DNV GL and Inmarsat.

    The project also has the support of shipowners and operators. The tests of sensor arrays are being carried out aboard Finferries 65-metre double ended ferry, the Stella, which operates between Korpo and Houtskär. ESL Shipping Ltd is helping explore the implications of remote and autonomous ships for the short sea cargo sector.

  • Navigation progress for indoors and UAVs

    Navigation progress for indoors and UAVs

    I didn’t get to this year’s IEEE/ION PLANS meeting in Savannah, Georgia, in April, but I did find a few papers that interested me. You might have read past articles of mine that looked at the challenges of indoor navigation. And, of course, unmanned vehicles technology also is one of my favorites.

    So, I was pleased to find papers that addressed a few key issues for me:

    • An approach that employs cooperative smartphones to achieve about 3 meters indoor location.
    • Another look at the problems in using smartphone embedded GNSS for RTK positioning.
    • Relative positioning between UAVs using GNSS, radio and inertial, and also adding image processing in a GNSS denied environment.
    • Analysis of encounter-alerting issues for UAV detect and avoid systems.

    Indoor navigation

    Indoor navigation is an area which is seeing quite intense research, and several companies have now put initial products on the market. The general approach has been to use sensors within smartphones combined with radio-frequency (RF) signals which seem to be readily available in stores and malls which indoor location is finding commercial applications.

    If a position can be generated by an internal GNSS receiver within the phone in an outdoor setting prior to entering a building, the trick is to carry that position forward as GNSS signals disappear when the user moves away from the entry area. Inertial sensors in the phone are usually not accurate enough to do this job on their own, so ranging using RF from Bluetooth and Wi-Fi transmitters/beacons may be integrated to provide a position solution. Magnetic sensors in the phone have also been used to detect fixed metal structures within a building and use this data to aid location determination.

    The problem is that you need an up-to-date database of where the Wi-Fi and Bluetooth are located, and it has been taking a lot of work to map or “fingerprint” the interiors of buildings — and guess what, these “beacons” often are moved after a mall or store is mapped, so RF ranging can become quite inaccurate.

    So, fearless investigators from the University of Buckingham and University of Northampton in the U.K. have come up with the concept of using ranging between cooperative smartphones to aid each other and achieve location accuracies of 5-10 meters.

    While outdoors with good GNSS position, the inertial sensors in each phone are calibrated, each phone gets position using its internal GPS and a network is formed between the phones using their relative positions. Then when a phone goes inside the building, step counting is used to maintain relative positioning in the network. This can result in around 3 meters positioning for the interior phone.

    Well, yes, not everyone has two other buddies waiting around so one guy can go in and find the classic comic store, but for applications such as firefighters, urgent/health care, and security/police, this approach might work well.

    Cooperative smartphone location overview.
    Cooperative smartphone location overview. (From “UNILS: Unconstrained Indoors Localization Scheme based on cooperative smartphones networking with onboard inertial, Bluetooth and GNSS devices,” H.S. Maghdid, A. Al-Sherbaz, N. Aljawad and I.A. Lami.)

    Another paper looked hard at the options there might be to resolve problems with GPS performance which has previously precluded running RTK on smartphones. If we could achieve centimeter positioning on a mass-market basis, many current applications which are inhibited by cost, could become possible and revolutionize even the way we live. People have already used external solutions to solve some of the problems, but leading researchers at Texas U, with Broadcom and Radiosense support, may have come up with a self-contained solution.

    It is known that there are issues with the capability of the GNSS chip and oscillator components in smartphones — the observables they produce are not currently of sufficient quality to sustain RTK performance. So these researchers worked with Broadcom, who supplied them with an Android smartphone, which provided access to raw code and carrier-phase outputs and was also able to process these measurements internally.

    A smartphone’s Android software stack with the GNSS components and data flow highlighted.
    A smartphone’s Android software stack with the GNSS components and data flow highlighted. (From “On the Feasibility of cm-Accurate Positioning via a Smartphone’s Antenna and GNSS Chip,” T.E. Humphreys, M. Murrian, F. van Diggelen, S. Podshivalov, K.M. Pesyna, Jr.)

    Carrier phase measurements in smartphones suffer from five anomalies not found in survey-grade GNSS receivers — but four of these can be fixed in post-processing. The remaining phase measurement error increases with time and precludes RTK centimeter-level positioning — it could be the result of round-off error due to processing limitations. Otherwise it seems possible that carrier-phase differential GNSS positioning might be achievable.

    However, the researchers also studied antenna performance and found that its gain pattern was significantly affected by strong local multipath. The impact is that deep, unpredictable fading and large phase error will compromise centimeter-accurate positioning.

    So we’re not quite there yet, but with a new smartphone version showing up almost every other year, it is always possible that researchers and manufacturers will eventually evolve designs in the right direction, and ultimately solve the problem.

    Unmanned aerial vehicles

    Meanwhile, researchers at West Virginia University have been investigating methods to maintain relative positioning between UAVs in flight. With drone “swarms” and cooperative drone missions becoming more common, if a simple method could be derived to maintain relative separation, these applications could become more prevalent, especially in a GPS denied environment.

    So, with only noisy ranging radios between UAVs, and an onboard navigation system solution on each vehicle, the researchers set about developing an algorithm which can maintain relative position. The solution is complicated by the geometry between the UAVs, how often range measurements are made, and the noise in those measurements. To constrain these variables, the study was run assuming the UAVs travel at the same altitude.

    The study concluded that— provided the UAVs travel in the same direction, parallel to each other — that their algorithm could find a solution all the time. The focus of the study appears to be on determining hearing and relative bearing between the vehicles and results were varied depending on the frequency of range measurements, the amount of noise and the geometry. So a few steps forward along the path towards making drones work together in a hostile environment where GPS is jammed. (See “Cooperative Relative Localization for Moving UAVs with Single Link Range Measurements,” J. Strader, Y.Gu, J.N. Gross, M. De Petrillo, J. Hardy.)

    Another study on the same problem of maintaining relative position between drones was also undertaken by West Virginia University, Systems & Technology Research and the Air Force Research Laboratory. However, their solution didn’t only use ranging between vehicles. It took advantage of inertial measurements on each drone, computer vision calculations derived from downwards looking cameras on both UAVs, and finally magnetometer measurements were also added into a Kalman filter solution.

    UAV platform payload diagram and assumptions.
    UAV platform payload diagram and assumptions. (From “Unmanned Aerial Vehicle Relative Navigation in GPS Denied Environments,” J. Hardy, J. Strader, J.N. Gross, Y. Gu, M. Keck, J. Douglas, C.N.Taylor.)

    With several additional sensor measurements, the researchers were able to predict that relative positioning could be maintained in a GPS denied environment. They also considered ranging radio, magnetometer and vision update rates, and the performance/update rate of various quality inertial sensors. The principle objective is to enable accurate target hand-off between drones as one approaches the other. Overall, they found their model could support 10-meter-level position and 0.5 degree accuracy.

    Finally, for safe operation of UAVs in the U.S. National Airspace System (NAS), minimum Detect and Avoid (DAA) standards for small to medium size UAVs are being developed for operations within drone-accessible airspace. DAA has to provide the “see and avoid” for unmanned aircraft systems (UAS) that pilots of manned aircraft use to avoid other aircraft. So surveillance sensor information needs to supply the UAV and the remote Pilot in Command (PIC) operator with the situational awareness needed to remain well clear of other aircraft.

    Part of what DAA should provide are alerts working to universal standards for all UAS.

    HazardZone
    Zones used in alert evaluation. (From “Analysis of Alerting Performance for Detect and Avoid of Unmanned Aircraft Systems,” S. Smearcheck, S. Calhoun, W. Adams, J. Kresge, F. Kunzi.)

    The research presented by CAL Analytics and General Atomics (with technical support and guidance by RTCA committee SC-228 and NASA) outlined the evaluation alerts generated when other aircraft are anticipated to penetrate into a well-clear volume around a UAV.

    Alerts can be “missed,” “late” and “early” — all of which can impair DAA performance and safety and which need to characterized and mitigated. Sensors currently under consideration for use in DAA include Automatic Dependent Surveillance Broadcast (ADS-B), active surveillance transponder and airborne radar — this study looked at ADS-B and radar and the trade-off that they provide related to desirable and undesirable alerts.This analysis will likely feed into the development of UAS DAA alerting standards and requirements.

    Typical DAA tracker approach.
    Typical DAA tracker approach. (From “Analysis of Alerting Performance for Detect and Avoid of Unmanned Aircraft Systems,” S. Smearcheck, S. Calhoun, W. Adams, J. Kresge, F. Kunzi.)

    Radar surveillance errors were found to increase the probability of Missed, Late, Short, Early and Incorrect Alerts, all of which is bad news for radar. ADS-B surveillance errors increased the probability of Short, Early, and Incorrect Alerts. However, ADS-B did not lower performance as much as radar — better news for ADS-B. All levels of surveillance errors were seen to increase the amount of alerting jitter, with radar seeing the most significant undesirable effects.

    Guardian UAS used in DAA tests.
    Guardian UAS used in DAA tests.

    Highly reliable, proven DAA systems are likely an essential part of the safety system for UAS if they are to become a regular part of operations in the NAS. General Atomics has tested a DAA system including GA’s Due Regard Radar (DRR) aboard a U.S. Customs and Border Protection (CBP) Guardian Unmanned Aircraft System (UAS), a maritime variant of the Predator B UAV. The DAA system also includes Honeywell’s Traffic Alert and Collision Avoidance System (TCAS) and Sensor Tracker, specifically designed for DAA.

    Schiebel Camcopter S-100 demonstrating detect and avoid system.
    Schiebel Camcopter S-100 demonstrating detect and avoid system.

    And, also in December of  last year, a Schiebel Camcopter S-100 flew demonstration flights with an NLR-developed AirScout Detect and Avoid System. Two helicopters flew “intruder” profiles against the UAV during the demonstration. The Camcopter S-100 flew several scenarios and “unexpectedly” encountered an intruder aircraft. The system determined in real time the corrective action to maintain separation from the intruder aircraft.

    So, progress on indoor navigation, research towards running RTK on smartphones, relative positioning between UAVs, and advances in Detect and Avoid solutions for UAVs. Something of a mixed bag, but all promise further progress around different solutions for a number of market navigation segments.

  • Naval Academy brings back celestial navigation courses

    Sextant-PD-300Imagine life without GPS. For those of us old enough, that might not be hard to do. For younger people, it’s almost unimaginable. Now imagine that GPS — for whatever reason — is suddenly unavailable. What if you’re not on land, where printed maps are filled with landmarks? What else do you rely on?

    Before GPS, early explorers navigated by the stars using celestial navigation and a sextant, the same basic techniques that guided ancient Polynesians in the open Pacific and Magellan around the world (the first sextant device was invented in 1757 by John Bird).

    As Don Jewell describes in his gripping Defense PNT newsletter column “Lost Over the Pacific,” a massive electrical failure on his aircraft caused the crew to rely on his skills navigating with a sextant. “The crew regarded me with some skepticism as they realized I intended to use an old-fashioned sextant to determine the speed and heading and then navigate a multi-hundred-million-dollar modern reconnaissance aircraft,” he recalls.

    Despite its usefulness when things go sideways, celestial navigation was pulled from the curriculum at the U.S. Naval Academy in the late 1990s, considered “outdated.” The course time was replaced with GPS and electronic navigation. Among the fleet, the Navy ended training in celestial navigation in 2006. A similar course at the U.S. Coast Guard Academy ended 10 years ago, but some instruction remains in theories of celestial navigation, and cadets use a sextant aboard the tall ship Eagle.

    Now, however, what’s old is new again. The Naval Academy has brought back celestial navigation courses, recognizing the importance of giving future naval officers the ability to find their position out at sea in case GPS is unavailable through jamming or hacking.

    After all, an old-fashioned sextant can’t be hacked.

  • The GPS Update Syndrome

    The GPS Update Syndrome

    Don Jewell
    Don Jewell

    The I-want-free-advice syndrome was once called the “Doctor Syndrome” or “Expert Syndrome.” I have recently heard it referred to as the “unsolicited advice” syndrome, because there is a new version that involves shaming the expert in to giving free advice.

    Occasionally those of us with expertise in an area of interest, which certainly include doctors and lawyers, are faced with tough decisions involving rules, regulations, laws and conflicts of interest.

    We are all guilty of these ethical violations in one way or another. On an airplane you discover your seatmate is a doctor of osteopathic medicine; not five minutes have gone by and you are telling him or her about all your aches and pains and seeking advice. My daughter, a clinical psychologist, says this frequently happens to her, but legally it is not a syndrome, although it could certainly be described as a phenomenon.

    Regardless of the nomenclature, the newest wrinkle goes like this, as stated by a congressman at our table at a fundraiser I attended recently, when he was asked about the troubled OCX program (Next Generation GPS Operational Control System) and GPS funding in general. “Well, I don’t know much about GPS or navigating, but this is what I know about OCX and GPS. I am sure Don will correct me if I am wrong…”

    I mention this phenomenon because for position, navigation and timing (PNT) issues, it is growing at an alarming rate. For instance, my 10-20 emails per day asking about PNT issues have grown over the past few weeks more than tenfold. I perceive that many of you are confused and concerned about the future of GPS, PNT and GNSS in general.

    With the House Armed Services Committee deleting more than $420 million from the GPS budget line for OCX in the 2017 budget and canceling funding for certain Acquisition, Technology and Logistics (AT&L) positions dealing with acquisition, there are all kinds of rumors and innuendo floating around. [Editor’s Note: the Senate did not make the same deletions, so this must be worked out in congressional committee meetings before the end of September]. So, I went out and formally asked the experts (GPS Directorate, Lockheed Martin and Harris Corp among others) what they think the future holds for GPS. Here is what I learned…

    Artist's concept of the nextgen GPS III satellite (courtesy of the USAF).
    Artist’s concept of the nextgen GPS III satellite (courtesy of the USAF).

    GPS III Spacecraft. According to Colonel Steve Whitney (USAF), the director of the Global Positioning Systems Directorate, Space and Missile Systems Center (SMC), Air Force Space Command (AFSPC), Los Angeles AFB, California: “The GPS III program is actively engaged in production of the first eight [GPS III] satellites (SV), while proceeding ahead with contracting actions for the ninth and tenth spacecraft. “

    Colonel Whitney went on to explain, “We have had several notable successes over the last year, including delivery of the first two navigation payloads [from Harris Corp] and completion of the first spacecraft’s environmental tests (acoustic, thermal vacuum and electromagnetic compatibility). As we prepare to accept delivery of the first spacecraft, the directorate is gearing up for the Mission Readiness Campaign and satellite launch.”

    I spoke independently with representatives from both Harris Corp and Lockheed Martin, and they expressed the same opinions. Work is progressing toward a launch of the first GPS III SV hopefully sometime in 2017.

    Of course, all of the companies mentioned and many others are also involved in the follow-on production of GPS III satellites known officially, oddly enough, as the:

    GPS III SV11 + Follow-On Production Phase One (1). According to Colonel Whitney, “The GPS SV11+ program is implementing a phased acquisition approach to determine first if viable alternate sources exist for a production-ready spacecraft. We successfully awarded three Phase 1 contracts on 5 May 2016, and are working with all three vendors to inform our follow-on approach.”

    For those of you who have not been keeping up, the three Phase 1 contracts were in the amount of $5M to each company. LMCO is included in the competition and was one of the three companies. To go into a bit more detail, the three GPS III awards are firm-fixed-price contracts that are not-to-exceed $6 million; the base contract plus two $500,000 options. The base contract period of performance is 26 months, and each option extends that time by six months for a total period of just over three years or 38 months.

    At the end of the competition, the GPS Directorate will award one GPS III Phase 1 Production Readiness Feasibility Assessment contract to one or more of the three companies:

    Colonel Whitney’s boss, Lt. Gen. Sam Greaves, who is the Space and Missile Systems Center commander and Air Force program executive officer (PEO) for space, said: “Industry told us they were ready to compete for the GPS III space vehicles. We look forward to working with Boeing, Lockheed Martin, and Northrop Grumman to assess the feasibility of a follow-on, competitive production contract.”

    The USAF has issued an artist’s concept of the GPS III satellite, but seriously, I have listened to the proposals from all three companies in detail, and the proposals are all so radically different that the picture is just that, an artist’s concept, it may not even be close to reality.

    Artist’s concept of the nextgen GPS III satellite (courtesy of the USAF).

    Certainly, $5-6M is not much money in the scheme of things, certainly not enough to design and build a GPS satellite from scratch, but it is a show of good faith on behalf of the U.S. government, proving they are serious in their search for a new and improved PNT satellite in the GPS III family.

    Next-Generation Operational Control System (OCX). The original OCX contract was awarded for somewhere slightly south of $900M for a six-year total effort to deliver a new Full Operational Capability (FOC) ground control system for all GPS satellites except the long-lived GPS IIAs. The federal government, having watched programs like OCX go south before, took the Raytheon bid and quietly doubled it and assured everyone they had the program well in hand. The government assured us time and again that OCX would never breach Nunn- McCurdy levels as they planned for double the cost. Smart move, but OCX costs finally reached double the original estimate plus 25 percent, which triggered the Nunn-McCurdy breach on June 30.

    Now Raytheon and the government have until October to decide whether to continue with the OCX program. However, Colonel Whitney and the folks at SMC remain confident; he kindly describes the current status of OCX this way: “The OCX team continues to pursue a restructured plan approved by the Defense Acquisition Executive [USD (AT&L)] and will hold its next deep dive with the Secretary of the Air Force [SECAF] and USD (AT&L) in early July [maybe this week]. Raytheon is driving for Functional Qualification Testing of the GPS III Launch and Checkout System (GPS LCS and OCX Block 0) in August 2016.”

    My sources tell me that a realistic date for OCX FOC, based purely on past performance, software issues and cyber-security concerns, is 2023 with a total cost of $4.2B. This may all be academic if OCX cannot clear the Nunn-McCurdy hurdles.

    The interesting story here is that there are alternatives. This brings us to the…

    GPS III Contingency Operations or Cops, which Colonel Whitney described this way when I asked him about it. “We [USAF, SMC] awarded the GPS III Contingency Operations effort on 3 February 2016 on an expedited basis with the task of delivering the capability to put on-orbit GPS III spacecraft into operations, providing legacy mission capabilities. We successfully completed the Preliminary Design Review (PDR) on 11 May 2016 and are on-track for Critical Design Review (CDR) in November 2016.”s

    What the Colonel meant to say — my words, not his — is that we (the U.S government) are finally hedging our bets. Just in case OCX does not come to fruition, both for launch and operations, we know we need to put a GPS III satellite on orbit soon so we can check it out before all the satellites are produced and sitting in a warehouse and we discover a major anomaly. We are running out of time.

    If all of the GPS satellites are produced (and there are only six or eight more to be built under the current contract depending on the future award schedule), and not one of them has been launched, then the program is in trouble. If LMCO does not win the follow-on contract, then the GPS III production line will be shut down at LMCO and experts scattered to the winds. Spare parts for a satellite in storage will be hard if not impossible to find, much less repair or install. If the first GPS III satellite is not launched until after production ceases and a major flaw or anomaly is discovered, then the government’s options are slim to none.

    To prevent a worst-case scenario, the government must launch a GPS III satellite, and soon. Certainly a date in 2016 is preferable, but a 2017 date will suffice, according to my sources. However that is doubtful with an OCX-based launch program that has yet to launch a satellite.

    Kudos to the government for looking at OCX alternatives, and for looking down the road at…

    Military GPS User Equipment or MGUE. Colonel Whitney, who successfully ran this program for several years before becoming the overall GPS SPO director, knowledgeably described the current MGUE effort this way. “We have taken delivery of the first GPS Military GPS User Equipment (MGUE) Final Test Articles this past month. These articles are going through initial checkout in the test labs as we prepare for integration into our lead platforms, like the B-2 Bomber.”

    Approving the final test articles is a big deal for MGUE because it not only puts the products in the hands of operational integrators and users, but opens the door for a multitude of changes necessary to incorporate the latest up-to-date technology. This technology hopefully includes the use of GNSS signals and capabilities as well as other PNT signals and augmentations that can now be incorporated.

    By the way, the congressman at the fundraiser dinner that I mentioned at the beginning did a credible job, but managed to get most of it wrong. But then, congress has so much more on its plate than GPS. That’s why the real experts need to make sure they keep everyone informed.

    Wooldridge and Ramo on the cover of Time Magazine, 1957.
    Wooldridge and Ramo on the cover of Time Magazine, 1957.

    Simon Ramo

    I hate to end on a sad note, but I must acknowledge the passing of a legend in the aerospace industry. Dr. Simon “Si” Ramo, who I knew well and worked with for many years early in my career, passed away on June 27 at the age of 103.

    Si, who held two doctorates, was already a leader in the aerospace industry when I was born, and I credit many of his well-known books (he was a prolific author) for drawing many a young person to space, rockets, the dynamics of space launch, and engineering.

    Dr. “Si” Simon Ramo
    Dr. “Si” Simon Ramo

    Si cofounded TRW Inc. in the late 1950s by taking two companies — Ramo-Wooldridge and Thompson Products — and leading them into the ICBM (Intercontinental Ballistic Missile) world. He was a tireless promoter of the space industry. The world will not soon see another character, gifted leader and entrepreneur like Si Ramo.

    Until next time, happy navigating, and remember: GPS is brought to you free of charge by the United States Air Force.

  • Movie preview: ‘The Night GPS Failed’

    Movie preview: ‘The Night GPS Failed’

    shutterstock_343138097-damage

    Something’s missing from the summer lineup of blockbuster movies, the disasters, apocalypses, invasions and superhero dust-ups that we’ve come to rely on for worldview. And try as it might, the U.S. presidential campaign just can’t fill the gap. So I flew down to Hollywood and raised $617 million in a fast set of power lunches. By lucky coincidence, several favorite actors were available. We did a quick wrap, and the film’s now slated for late-summer release. The special effects are, if I may say so, spectacular. Here’s the preview for “The Night GPS Failed.”


    Matt Damon (as Mr. Suburban America, entering front door): Honey? I couldn’t get any money. The ATM’s on the fritz.
    Lake Bell (off-screen): Are you —ing kidding me?! I need cash right now! (enters carrying cell phone and credit card) The delivery service won’t take my credit card, and I can’t get customer support because the phone doesn’t work! You’ll have to drive to the store.
    Damon: I don’t know. Pretty dangerous out there. Traffic lights aren’t working.
    Bell: What is going on? I need money! (throws cell phone).
    Damon (ducks and shrugs): What do you want me to do, write our Congressman?


    Don Cheadle (on short-wave radio, seated at control panel in room of huge display screens): The grid’s down! (stands and turns to each screen in turn). Cincinnati, Chicago, Tulsa, San Diego, they’re all down! (repeatedly bangs control panel buttons with radio.) ——!! Everything’s down! The whole damn country!


    Patricia Clarkson (as U.S. President): I’m told it will take 30 days to fully restore the national power grid and financial markets. Colonel, what has happened to the constellation?
    J.K. Simmons (as Air Force Space Command chief scientist): Ma’am, we’re not sure yet. Solar particle damage or a bad upload, probably not, but not ruled out. We suspect widespread jamming. It could be mixed with spoofing.
    Albert Finney (as Chairman of the Joint Chiefs of Staff): Heh, heh. At least the Russkies aren’t doing any better. The Chinese and Europeans are having trouble, too. Military security is not at risk. We don’t think.
    Clarkson: What’s your contingency plan, General?
    Finney (spreads his arms): We have one-tenth of a backup system almost halfway built. Funding is an issue . . .
    Clarkson: Funding my ass! The whole global economy just went to hell in a handbasket, General! I don’t have any money! (throws Red Telephone).
    Finney (ducks and shrugs): What do you want me to do, write my Congressman?


    Bob Dylan (singing on soundtrack): That long black cloud is comin’ down . . .


    Based on a true story: “What Happens If GPS Fails,” by Dan Glass, The Atlantic magazine, June 2016.

  • BLM’s new GNSS protocols may set undesirable precedent

    alaska-907724_640

    Alaska. “The Last Frontier” is a fitting slogan for this great land. The rugged terrain and harsh winters make an environment that only the bravest inhabitants can stand. Here, one of the latest surveying battles is being fought; not between land owners, but within the professional surveying community itself and pitting technology against historical tradition.

    In the beginning…

    The United States agreed to purchase Alaska from Russia in 1867 for $7.2 million dollars, or about two cents an acre. In 1959, Alaska, with a land mass larger than Texas, California and Montana combined, became the 49th state in the union.

    For the professional surveyor, more than 20 million acres of federal government land is scheduled to be measured and divided for conveyance to the state for eventual sale to private individuals.

    Surveying can be a challenging profession, and creating new townships in Alaska is no exception. In addition to the difficult environmental conditions, new procedural and technological advances are contesting historical means and methods of the creation of newly surveyed township tracts. The two main items are:

    • establishing coordinate values at corners instead of setting monuments.
    • GNSS and potential issues with atmospheric interference and lack of satellite coverage.

    We will discuss the challenges ahead for the future of surveying in Alaska and how it will affect parcel division. While it is too soon to know whether or not this will bottleneck sales of parcels to new landowners, it does bring many technical and procedural questions for surveyors to the forefront.

    Challenging historical methods

    From the early days of our new nation, surveyors from the Bureau of Land Management (BLM) followed long standing procedures and placed retraceable monuments at various intervals along township boundaries for tract establishment, with two mile intervals being the predominant length for parcels in Alaska. The position of these monuments are held by subsequent surveyors to retrace these tracts for the state or individual owners.

    During the course of the original field surveys, crews tasked with establishment of the new corners will note natural and artificial features for reference to these new parcel lines. These features may be trees or forestry lines, streams and rivers, mountains or glaciers. Because of these environmental challenges, these surveys take a great deal of time and effort to traverse through the difficult Alaskan wilderness.

    However, the physical act of performing the survey is the only way to establish accurate ties to features found along the way. Surveyors will establish permanent markers at the chosen intervals along the township lines with measurements to nearby features for future retracement. Once placed, the monument becomes a corner for the township parcel and its position holds over any distance or angular measurement to other monuments or reference ties.

    Performing these surveys is very costly and takes a great deal of time, so finding ways to reduce the budgetary expenditure for this task has been a priority for the BLM. Modern equipment and technology has improved efficiency and cut down on some necessary manpower, but it still takes a significant number of people to traverse through the dense areas of Alaska.

    The BLM has proposed the following changes to establishment of township and section corners during property establishment through a system referred to as a “Direct Point Positioning Survey” (DPPS):

    Implementation Direction: When preparing official surveys for areas of land selected by the State of Alaska pursuant to the Alaska Statehood Act, exterior boundaries of the selection area will be shown on the official plat by combinations of dependent resurvey, incorporation of record surveys where closure is met, and original survey. For original surveys, all angle points along the exterior boundary of the selection area shall be marked on the ground with a physical monument and shown on the official plat by reported coordinate and reference relationship to the NSRS datum and existing control stations. When deemed appropriate and directed in the Survey Special Instructions, other corner positions along, or internal to, the exterior boundary of the selection area can be reported and fixed by measure using reported coordinate and reference relationship to the NSRS datum and existing control stations and other marked corners of the survey with reported coordinates on the official survey plat. For surveys conducted using DPPS methods, if a corner is not marked with a physical monument, the geographic coordinate reported on the official survey record as fixing the corner location shall be accepted as the only evidence of the original corner position. For corners marked with a physical monument, the geographic coordinates reported on the official survey record shall be accepted as collateral evidence of the original corner position; the actual monumented location will remain the best evidence of the original corner position.

    The BLM goes on to state the following conditions for implementation:

    • Ease of unofficial location of boundaries on the ground by using satellite positioning in mobile devices for groups like miners, oil and gas lessees, recreational users, prospective land owners, etc.
    • More economical future legal surveys when the need arises to mark the corners of property boundaries
    • A clear plan for future surveys that will allow efficient procedures for private land surveyors.
    • Reduced boundary uncertainty and costs due to monument destruction or disturbance.
    • Compatible and accurate boundary framework for GIS and other geospatial databases.
    • DPPS methods generate a greater certainty of comer positions and they are correct, consistent and repeatable.
    • DPPS methods introduce an economy of resources in the future for leaseholders and landowners when additional parcel boundary demarcation is required because geographic coordinates referenced to a known national datum are directly reported on the survey record and do not need to be calculated from the legacy measurement of bearings and distances.
    • Adoption of DPPS methods avoids spending substantial funds on unnecessary procedures like recovery, maintenance and rehabilitation of physical monuments in future survey work.
    • Surveys conducted using DPPS methods can be completed much more quickly than surveys completed using historical methods, thereby facilitating quicker patent to the State.

    These new policies are reshaping not only how traditional surveyors perform their craft, but also flies in the face of more than 200 years of boundary establishment and case law determination of property rights. Surveyors follow a strict guide when evaluating evidence in legal descriptions and/or property boundaries:

    Priority of Evidence Rules:

    1. Possessory Evidence
    2. Seniority of Title
    3. Documentary Evidence
      a. Call for a survey
      b. Call for monuments
      i. Natural
      ii. Artificial
      iii. Record
      c. Distance (or Direction)
      d. Direction (or Distance)
      e. Area
      f. Coordinates

    Coordinates have historically always been the last resort for corner positioning and/or retracement use, yet the BLM feels that GNSS measurements have increased in reliability to a place where they can be more heavily relied upon for establishment of section corners and other significant points. This is where the second issue comes to light: positional accuracies using satellite-based measuring devices at high latitudes.

    GNSS measurement and environmental challenges

    For most of us “regular” surveyors in lower latitudes, our GPS/GLONASS measuring equipment operates with little to no trouble. Newer receivers are taking advantage of not only the U.S. and Russian satellites, but will eventually use the European Union Galileo satellites, China’s BeiDou, the Japanese QZSS and India’s IRNSS. Once these additional systems are operational, achievable accuracies worldwide will increase dramatically but we are still several years off.

    The issues GNSS users in higher latitudes face are not only lack of satellite coverage, but several factors of environmental interference within the atmosphere. The result of these conditions and hazards are scintillation, positioning errors and cycle slips. These are very difficult to predict, thus increasing data-collection time and efforts to catch potential errors.

    Scintillation occurs when rapid changes in amplitude and phase are observed and directly impacts the signal from the GNSS. Solar radio storms (caused by coronal mass ejection), large- and small-scale ionospheric structures (causing unpredictable values in environmental electrons) and geomagnetic activity (aurora) are also factors that affect signal, create cycle slips, and thus deteriorate the positional accuracy.

    Studies performed by several technical teams (including NOAA/NGS) have shown that variations in position occurs often at CORS stations with little or no warning. Ongoing studies are helping to establish potential patterns in the atmospheric intruders, but will require much more analysis.

    Some of these issues will be solved with more satellite coverage from the pending systems, but it will also require additional monitoring equipment to help forecast when potential environmental factors are about to occur. These systems will take time and money to develop, and thus increase the budgetary requirement for a new surveying procedure that was planned to save time and money.

    But what does this all mean? From the historical side, placing monuments only at perimeter corners and not at township and section corners will place an extraordinary burden on future surveyors to “follow in the footsteps” of the original surveyor.

    This flies directly against the duty of the retracement surveyor, so that alone will be a challenge. Studies have shown the instability of GNSS-derived accuracies as performed by highly trained scientists who are well educated at atmospheric recognition. Pairing a revised retracement procedure with providing GNSS-derived coordinate values with potentially faulty data instead of placing monuments is a recipe for disaster.

    The biggest issue for most surveyors with implementation of the DPPS method will be for other jurisdictions to follow suit. The main priority of the surveyor is to protect the public. Making a change to allow coordinates to become acceptable evidence will lead to many more boundary disputes and court cases. Too often I hear that one surveyor thinks his coordinates are better than the next (myself included), yet we are dependent on what the receiver gets and the software calculates.

    The surveyor tends to believe that GPS is “our” measuring device, and we have exclusive knowledge of its use and application, but we would be hard pressed to tell the client exactly what the equipment does to determine position and distance. A general understanding of your measuring tools is necessary, but it still comes back to knowledge of boundary law and the principles of how to apply them.

    While I applaud the BLM for proposing a new procedure to help reduce costs for new original surveys in Alaska, I’m also afraid of the residual effect everywhere else as it establishes a new precedent.

    So in the meantime, let the surveyors keep setting monuments and we will revisit the coordinate standard another day. And to quote the surveyor’s favorite geodesist, David Doyle: “Good coordination begins with good coordinates.” So let’s make sure we have accurate data.

  • Skyline PhotoMesh 3D: On-the-fly models while flying

    During my tenure as the GIS manager for the Atlanta Regional Commission, I had the opportunity to work with many first responders, primarily police, fire and E911. I always promoted the capabilities of GIS to develop a common operational picture.

    However, most first responders were not interested in becoming GIS experts, especially with traditional GIS software and ortho imagery. They just wanted easy and effective tools that would help them do their job better. Then Pictometry metric oblique imagery hit the scene. It was a game changer because it was easy to use and, most important, the oblique images provided a visual perspective that average users could grasp quickly. (See my 2008 column that explains why.)

    Soon, 3D model creation and navigation became common. In my opinion, 3D models are just a more robust way of viewing oblique views. 3D models are becoming more commonplace, but generating those models is more time consuming and resource intensive.

    A few of you may remember that four years ago, USSOCOM (U.S. Special Operations Command) had more than 20 — yes, 20 — different 3D model viewers. These were mostly proprietary systems from major contractors that required separate maintenance and support, and sometimes led to user confusion and delays, not to mention expense. USSOCOM appointed a team to evaluate and reduce the number of 3D viewers, and they got it down to two, with Skyline TerraExplorer being one of them.

    Building on that 3D reputation, Skyline Software Systems recently developed a 3D model creation capability that puts easy and rapid model creation in everyone’s toolbox. PhotoMesh is Skyline’s new 3D model creation software designed to build photorealistic 3D models as a fully automated process using auto-triangulation (AT) of multiple aerial images. Skyline can provide 3D model creation as a service or provide the software so customers can do the model creation in-house.

    Below is a screenshot of a sample model created using PhotoMesh from UAV video I shot. then geolocated by Remote GEO (see my February column). The below 3D model was processed locally by Skyline using a typical laptop, and the entire process was finished in under 35 minutes. However, if speed was critical, Skyline could generate the model in the cloud, with the whole process taking a minute or two.

    Here is a quick overview video that will give you an idea of the system capability.

    Live demo at GEOINT 2016

    While I was at GEOINT 2016 this May, I had had the chance to talk to Steve Marks, the director of business development at Skyline. He gave me an excellent video overview of PhotoMesh.

    Steve then provided additional detail in several aspects of PhotoMesh including:

    Other developers have come up with similar capabilities, but the Skyline system is the most robust I’ve seen, especially with the flexibility for very rapid model creation through the cloud or local creation in a disconnected environment. Additionally, unlike many other 3D model systems, the Skyline models do include trees and shrubs so viewshed and line-of-site analysis is very realistic and accurate.

    How would it be used?

    In actual use, I can envision first responders arriving at a scene. They could use legacy imagery such as Pictometry oblique images to build a historic as-built model. They could then launch UAV or manned aircraft and capture current geo-located video, selecting and processing images in PhotoMesh and getting back a current 3D model in minutes via the Skyline Cloud service.

    In a disconnected environment, the models could be generated locally but at a slower pace. The 3D models would permit horizontal, vertical and angular measurements. Other analyses could include: line-of-sight and viewshed, determination of blast zones and shielding, overhead hazards such as power lines.

    ince the system is so robust and easy to use, I can see it supplementing ortho and oblique imagery while providing a very user friendly common operational picture as well as very capable analytic tools.

    Retiring soon

    At age 70, I’m looking at real retirement later this year so I’m also looking for a relief. If you have an interest or know someone interested in taking over this monthly column, let me know. The folks at Geospatial Solutions and North Coast Media have been a pleasure to work with so I don’t want to leave without a replacement. You can email me at [email protected]