Upgrade to MAGNET Collage Web includes with new deliverable options.
Topcon Positioning Group has upgraded its MAGNET Collage Web, a web-based service enabling the sharing and collaboration of UAV and scanning data sets.
MAGNET Collage Web version 1.3 allow operators to work with more types of data with greater flexibility, including the ability to import BIM models, as well as CAD and GIS data.
MAGNET Collage Web and MAGNET Collage desktop software meet the demands of a diverse user-group. The latest update is designed to address an increasing need from the vertical building construction market segment to work in a single-software environment with BIM, scanning and UAV datasets.
“Now operators can view and publish BIM models, along with other data types, directly through the web browser to be sharable with more versatility,” said Alok Srivastava, director of product management. “MAGNET Collage Web can be used to overlay as-built laser scans and design data to visualize proposed changes and detect construction issues. The software supports OBJ, FBX and 3DS formats.”
The upgrade to MAGNET Collage Web also includes new direct publishing functionality for CAD and GIS data files through the browser.
“Operators can now overlay 3D point clouds and reality models with CAD and GIS design data, including support for DXF, SHP, KML, GML and GeoJSON formats,” said Srivastava.
The upgrade to MAGNET Collage Web also introduces advanced sharing controls including the ability to fully customize layer visibility, appearance, window layout, feature selection and camera position.
“The updated customization controls allow operators to share and present their projects exactly the way they mean to with a multitude of viewing options, allowing specific features to be highlighted as necessary,” said Srivastava.
Additionally, MAGNET Collage Web can now be accessed through the Topcon “Blue Bar” that allows direct access to the service from any Topcon website. The universal account and application management toolbar is embedded at the top of Topcon web pages.
Kinematic Ground Control point for UAV photogrammetry: A dynamic duo of UAV and mobile van combine to deliver the accuracy of conventional methods with only 2+2 ground control points at the ends of the corridor.
By Ismael Colomina, Pere Molina and Roberto da Silva Ruy
A Brazilian and a Spanish company, ENGEMAP and GeoNumerics respectively, have finalized the accuracy evaluation of a mission conducted with the latter’s mapKITE technology on a Brazilian motorway in 2018.
The goal of the evaluation was to confirm the advantages of the mapKITE method and its kinematic ground control point (KGCP) concept over conventional corridor mapping methods.
The mapKITE and the conventional method delivered comparable accuracy results — the difference being that the latter requires a dense set of surveyed ground control points (GCPs) while mapKITE does the job with almost no GCPs.
For this purpose, a 4-kilometer segment of the Rodovia Raposo Tavares in São Paulo state was populated with a set of 37 evenly distributed, signalized, accurately surveyed ground points. The set was divided into two subsets of 23 GCPs and 14 ground check points (GChPs) — the ground truth — respectively. The 4-km road segment was also covered by 189 drone images and their corresponding 189 KGCPs. The image set was processed as a conventional aerial corridor block:
with the integrated sensor orientation (ISO) method in a 23 GCP + 14 GChP configuration, and
as a mapKITE aerial corridor block in a 4 GCP + 14 GChP + 189 KGCP configuration.
The two processes produced similar accuracy results: mean (μ), empirical standard deviation (σ) and root mean square (rms) error of the photogrammetric determination of the horizontal (EN) and vertical (h) coordinates of the GChPs against the ground truth. (All units are stated in millimeters.)
The mapKITE configuration uses only four GCPs (two at each end of the road segment) in contrast to the 23 GCPs of the conventional method. Nominal flying height of the drone was 120 meters above ground, producing an average ground sampling distance (GSD) of 2.3 cm. Forward image overlap was 80% resulting in a base-to-height ratio of 0.157.
MapKITE is a GeoNumerics patented method for 3-dimensional corridor mapping that combines the two latest geodata acquisition methods, terrestrial mobile mapping and aerial drone-based mapping. MapKITE is a tandem terrestrial-aerial mapping method and system composed of:
a terrestrial mobile mapping system (land vehicle and sensors) carrying
an optical metric target on its roof;
a drone aerial mapping system; and
a real-time virtual tether and post-mission software.
In a mapKITE mission, the drone follows the land vehicle, and thus the vehicle target becomes a kinematic ground control point visible and measurable on each image. It is a high-accuracy, high-resolution Earth observation method. MapKITE combines the advantages of mobile land-based encompassing images and 3D point clouds. MapKITE combines the advantages of mobile land-based (manned) and aerial drone (unmanned) mapping systems.
GeoNumerics (Castelldefels, Spain) is a research and development company specializing in geomatics and accurate navigation.
ENGEMAP (Assis, Sao Paolo, Brazil) is one of the largest and oldest mapping companies in Brazil. It has more than 100 employees, three aircraft, two mapping land vehicles, a number of rotary- and fixed-wing drones and a record of accomplished mapping and cadastral projects. ENGEMAP is officially authorized by the Brazilian Ministry of Defence (MD) and the Brazilian Department of Airspace Control (DECEA) to conduct mapKITE commercial flights in Brazil.
MANUFACTURERS
The mapKite campaign was conducted with a Sensormap SMM terrestrial mobile mapping system and a UAVision UX Spyro drone equipped with a NovAtel OEM2 GNSS dual-frequency receiver with a Maxtena antenna and a Sony α7R camera with a 25-mm camera constant lens. The INS/GNSS system in the Terrestrial Vehicle was a Span-CPT (Novatel) including dual-frequency antenna and DMI wheel sensor.
ISMAEL COLOMINA is chief executive and chief scientist at GeoNumerics. He has a Ph.D. in mathematics from the University of Barcelona.
PERE MOLINA is advanced applications program manager at GeoNumerics. He holds a master’s degree in mathematics from the University of Barcelona and a master’s in photogrammetry and remote sensing from the Institute of Geomatics, Catalonia.
ROBERTO DA SILVA RUY is technical manager at ENGEMAP. He has a Ph.D. from the Universidade Estadual Paulista.
Global UAV Technologies Ltd. has completed a drone-based geothermal energy exploration survey for Borealis GeoPower Inc. The survey used UAV-mounted geophysical and thermal imaging sensors over an area in northern British Columbia, Canada.
Global UAV subsidiary Pioneer Aerial Surveys collaborated with Hummingbird Drones to collect and analyze high-resolution magnetometer and thermal data over the 2,200-hectare survey area.
The survey was conducted using both day and night flight operations to maximize efficiency and data quality. The survey produced high-resolution deliverables on the geological and geothermal features of the survey area.
The work was conducted at the Terrace, British Columbia, geothermal project, near the location of one of the world’s largest hot springs. Borealis is refining its reservoir model in advance of drilling in 2019.
Yuneec International’s commercial hexacopter, the H520, will now optionally be available with an RTK (real-time kinematic) system from the Swiss company Fixposition.
Under difficult GPS conditions, such as in cities or canyons, the RTK system ensures maximum precision and centimeter-precise positioning. The fully integrated RTK satellite navigation enables extremely accurate recurring images and faster 3D mapping. It also makes automated inspection flights easier and more precise, the company said.
The new H520 RTK is suitable for commercial applications that require maximum precision. By using RTK technology, the H520 can now fly much closer to objects for inspection as the UAV positions itself precisely in the centimeter range (1 cm + ppm horizontal / 1.5 cm + ppm vertical) rather than in the meter range, which is standard for the H520.
This accuracy is paramount for applications where several images need to be taken at the same location on different days including:
documenting progress on construction sites,
inspecting mountain landscapes to prevent natural hazards such as rock falls or avalanches, and
forensic accident scene reconstruction.
In addition, the satellite navigation system makes it possible to significantly reduce image overlaps, which means fewer photos and shorter model calculation times, maximizing efficiency in workflows.
The RTK system is not only fully integrated into the hardware, but also into the UAV’s software. This means the user retains the full range of functions of the DataPilot software, including mission flights.
The H520 RTK works with two components: the RTK module on board the H520 and a base station on the ground. For precise navigation, the module supports constellations of up to three different satellite systems from GPS, GLONASS, Galileo and BeiDou.
If the use of a ground station is not possible, the system can also be operated with a national reference station network (network RTK). The network RTK is provided by third-party providers and requires an internet connection, such as a mobile hotspot. All data including satellite data is recorded, which makes the H520 RTK suitable for post-processed kinematics (PPK).
The H520 RTK will be available in the second quarter of 2019. Technical specifications are available here.
Looking around the industry over the last few weeks, there continues to be a flood of innovation that promises new approaches for unmanned aircraft in addressing several new opportunities. This month I cover a flying taxi at the 2019 Consumer Electronics Show (CES) in Las Vegas, greater range for multi-copters using fuel cells, a potential huge drone in the making, and a potential Florida controversy over use of a tethered aerostat — interesting stuff!
Bell Flying Car/Air Taxi
At CES of all places, there was a new idea for air-taxis — not yet a UAV, but with the promise of future autonomous flight, it surely deserves a mention. Bell brought its latest commercial vertical take-off and landing (VTOL) mock-up to CES to test the level of interest in its concept of a flying car.
Lift and directional flight control are provided by six 8-foot ducted fans, each driven by its own electric motor and powered by a turbine-driven electric generation and back-up battery system. Using technology derived from the mil-spec V-22 Osprey Tilt-Rotor and its commercial V-280 cousin, the ducted fans pivot from horizontal for take-off to vertical for forward flight.
The concept vehicle at CES had a seat for the pilot, but the digital flight control system is envisaged to have autonomous flight capability — and there we have another approach for a UAV flying car/air-taxi — from one of the mainstay aviation manufacturers of helicopters with all the necessary experience to make it happen.
Fuel-Cell-Powered UAV Flies for 70 Minutes
There’s apparently a new way to overcome the short duration that is currently available for flying existing multi-rotor drones — don’t just rely on batteries, use hydrogen! Actually a hydrogen fuel-cell configuration that has recently been tested in the UK to extend flight time to 70 minutes, while carrying a 5-kg payload.
Test-drone with Intelligent Energy Hydrogen Fuel-Cell. (AVI screenshot supplied by Productiv)
The UK team includes Intelligent Energy, which supplies the fuel-cell, engineering firm Productiv, and UAS video company BATCAM, with funding provided by Innovate UK, a government-sponsored group that supports novel ventures such as this joint project.
Most existing battery-powered multi-rotor UAVs have endurance in the tens of minute (DJI seems to be approaching 20-30 minutes with some of its drone models). But longer endurance is really important for most operators, especially for capturing lengthy video, hence the interest and participation of BATCAM as the operator/consultant for the project.
Fuel cells provide a number of advantages over batteries with fast refuel, little vibration, quiet operation, zero emission at point of use, and around three times longer flight time. Intelligent Energy is making use of a portable hydrogen refueling system supplied by NanoSUN.
With BATCAM set to begin operational trials, the company is optimistic that further development of hydrogen fuel cells for UAVs will not only enable even longer video broadcasts but will solve the problem encountered with the difficult and expensive international transportation of Lithium polymer batteries.
Airship Moves towards Civil Certification
While we are in the UK, a huge 300-foot-long helium-filled airship called the Airlander 10 is again moving steadily down the path to gain civil approval by the Civil Aviation Authority (CAA), despite a previous crash in November 2017 due to a wayward landing cable.
The latest milestone was just achieved at the end of 2018 when CAA awarded Hybrid Air Vehicles Ltd. (HAV) a Production Organisation Approval, following on from earlier Design Organisation Approval by the European Aviation Safety Agency (EASA) in October 2018.
This behemoth airship is claimed to be the largest aircraft in the world, can carry 10 tons of cargo virtually anywhere on earth, stays airborne for up to five days, and can land almost anywhere. Powered by two forward-mounted rotating ducted fans and two aft fixed fans, all driven by diesel engines, the pressurized helium-filled envelope is 302 feet long, 143 feet wide, 85 feet tall, and has no internal support structures — all this with a cruise speed of up to 80 knots and a maximum altitude of 20,000 feet.
The Airlander is aimed at bulk cargo transport, but could also handle communication and observation/reconnaissance roles in both the military and commercial sectors. And it’s not so far away from becoming the largest unmanned aircraft in the world, either, should things eventually turn in that direction. Could there be potential for a greater payload without the extensive provisions for a pilot, with lower operating costs, potentially greater range and speed and/or operational altitude?
Miami Police use Tethered Aerostat
Miami police have been using a tethered aerostat to monitor large gatherings, such as the Dec. 28 Orange Bowl-related party called the Capital One Beach Bash. Presumably this use had a safety related motivation, and there was hopefully no intent to spy on partygoers.
However, I just became aware that police cannot fly drones in Florida to surveil people — there’s a law against it. But there is a provision in the Florida “Freedom from Unwarranted Surveillance Act,” which starts off: “If the law enforcement agency possesses reasonable suspicion that, under particular circumstances, swift action is needed to prevent imminent danger to life or serious damage to property,…”. Now, I’m no lawyer, but it would seem that this exclusion might possibly allow the Miami cops to monitor large gatherings where there might be a need to watch out for people’s safety – that generally being what we employ the police to do for us.
But the Florida lawmakers certainly believe that there is clearly a need to protect people’s privacy and to prevent unauthorized monitoring of an individual’s activities using drones. The provisions of Florida Statute 934.50 prohibits “the observation of such persons with sufficient visual clarity to be able to obtain information about their identity, habits, conduct, movements, or whereabouts” — a good thing to do to protect our freedom of movement and basic rights.
But you have to ask yourself if a general prohibition on the use of drones by police is the best thing to do when other police departments around the U.S. are gaining advantages from drone usage by speeding up and improving the accuracy of traffic accident investigations, for search and rescue, in crime scene reconstruction, for disaster response, and of course for improving officer safety — in fact, all the things that are already achieved through the use of police helicopters, but at a fraction of the cost.
Florida Statute 934.50 already has a significant number of allowable exceptions to enable a “law enforcement agency” and others to operate drones legally, but could it also be possible that these wider benefits of drone use might be fully exempted without infringing any personal liberties?
Conclusion
To sum up, we have a big aerospace company jumping in to help shape the future of unmanned air taxis; another drone fuel-cell application that significantly extends flight time; and progress towards certification of an airship that has benefits as a drone. Finally, police use of a tethered aerostat at an event stirs potential controversy, while other police forces benefit from the use of drones — a mixed bag of drone ventures that seem to have great potential.
Fugro has completed a landmark data acquisition campaign over the Turks and Caicos Islands, marking the first commercial success of its new Rapid Airborne Multibeam Mapping System (RAMMS).
Working under contract to the United Kingdom Hydrographic Office (UKHO), the company acquired more than 7,400 square kilometers of integrated, high-resolution bathymetric, topographic and image data. The resulting deliverables will support updated nautical charts and coastal zone management activities in the region.
Launched in August 2018, RAMMS is a highly efficient, next-generation airborne bathymetric mapping system that uses multibeam laser technology to deliver depth penetration and point densities, the company said. The compact sensor is deployed from small aircraft and can be integrated with other remote sensing technologies for simultaneous collection of multiple complementary datasets.
For the Turks and Caicos project, this approach made it possible to acquire near-shore (bathymetry) and coastal (topography and imagery) data in a single deployment, producing a cost-effective solution and advancing Fugro’s sustainability goals by significantly reducing fuel consumption.
“After years of development, it’s extremely gratifying to operate RAMMS commercially and to demonstrate to clients the value that this cutting-edge technology can bring,” said Mark MacDonald, Fugro Americas Marine Division hydrographic service line director.
He pointed to the massive Turks and Caicos project as an example. “The system’s multibeam lidar capability allowed us to achieve point densities that otherwise would have required vessel-based surveys. With RAMMS, we were able to avoid that additional time and expense, and significantly reduce health and safety exposure.”
Fugro is working on three additional RAMMS projects in the Americas region, one for UKHO in Belize, and two for the Canadian Hydrographic Society, in Quebec and Atlantic Canada. These projects are similar in scope to that of the Turks and Caicos project, combining bathymetry, topography and imagery for maximum value to clients, serving both navigation and coastal applications.
Based on steady interest in RAMMS, Fugro and technology partner Areté Associates are building an additional system to meet anticipated contracting volumes in 2019.
Fugro is also finalizing a cloud-processing capability, which will further improve client delivery by streamlining data review and approvals, and ultimately making data available for download-on-demand.
Additionally, Fugro aims to operate the unmanned aerial vehicle-proven system autonomously in 2019, providing further operational efficiency gains and increasing access to remote project areas.
By Alexander Rügamer, Daniel Rubino, Xabier Zubizarreta, Wolfgang Felber, Fraunhofer IIS, and Jan Wendel and Daniel Pfaffelhuber, Airbus Defense and Space GmbH
This work presents a new secure localization method that can be used for UAVs to obtain a new level of protection against hostile and unauthorized UAVs. While non-spreading code-encrypted (SCE) GNSS devices can be blocked, authorized UAVs using this method have unrestricted access to the non-spoofable and trusted SCE GNSS. The proposed method is to store short sequences of SCE PRN code chips on the user receiver before the mission.
The Precalculate & Process architecture. (Images: Fraunhofer IIS)
These SCE PRN code chips allow the user receiver to calculate at pre-defined points in time a secure and trustable SCE PVT position. Since no communication channel is required, this method mitigates the risk that hostile forces may try to jam the UAV’s radio control. Moreover, radio silence can be realized, which is beneficial or even required for some missions.
No dedicated security module required on the user terminal, no SWaP problems, no keying issues, no handling of controlled items on user side, no need for a communication link giving rise to the availability and radio silence issues, and no security issues due to the short SCE PRN code chip sequences valid only for the limited mission duration and inside a limited area.
Potential target markets for this method are police and special forces and other authorized users which are allowed to use certain SCE GNSS and would like to equip their UAVs with a secure, unspoofable positioning solution. Check out more information here.
Mountainous areas present special problems for surveyors, overcome by the expanded availability of multi-GNSS. (Photo: Trimble)
Today’s GNSS satellites transmit on three or more carrier frequencies. The quality of the data in these signals from GPS, BeiDou, Galileo, GLONASS and QZSS reveals the expected measurement precisions. This article explores the noise of the range residual and ionospheric residual to indicate the oncoming capabilities.
Today, four GNSSs transmit various codes on various carrier frequencies: the USA’s GPS, Russia’s GLONASS, Europe’s Galileo and China’s BeiDou. Most of the carrier phase and pseudorange data are available using civilian GNSS receivers. Improvements in signal quality as well as reliability of the satellites are foreseen through the generations, as well as the introduction of new signals, such as L1C, L2C, L5 carrier and codes, and M-codes, on top of the existing L1-C/A code and the P(Y) code on both L1 and L2. Improvements are also seen in boosting the transmitting power.
This article investigates the use of two approaches to analyze the relative noise in the various carrier phase and pseudorange observable for GPS, BeiDou, Galileo, GLONASS and Japan’s Quasi-Zenith Satellite System (QZSS) augmentation. Two approaches analyze the relative noise in the observables: the range residual and the ionospheric residual. Both techniques can also be used to detect cycle slips.
Range Residual
UAV survey operations benefit from multi-GNSS receivers. (Photo: Septentrio)
The range residual is simply the change from one epoch to the next in the difference in the range calculated using the pseudorange and the range calculated by the carrier phase on a specific frequency. The pseudorange values are scaled using the wavelength to an equivalent range in units of the carrier’s cycles rather than meters. Equation 1 illustrates the range residual between the pseudorange ρ on a specific carrier frequency and the carrier phase observable φ, using the wavelength λ of the carrier to scale the pseudorange. The values of these observables are compared between adjacent epochs.
RR = (p/λ) – φ (1)
Two adjacent epochs are used, as then the integer ambiguity value, as well as the ionospheric and tropospheric errors, and satellite and receiver clock errors are the same, or negligibly different at such small (<1 s) epoch intervals. Therefore, these are all canceled out, and the resulting value is the measurement receiver and observable noise. The pseudorange observable will be significantly noisier than the carrier phase observable, therefore this method is a good way to calculate the measurement noise for the pseudoranges.
Ionospheric Residual
Surveyors work the Berezitovy mine in the North Amur region of Russia. (Photo: Javad GNSS)
If the carrier waves traveled only through a vacuum, then a phase observation from a specific satellite to a specific GNSS receiver could be scaled and converted to an equivalent phase measurement on another frequency using the frequencies of the carrier waves. However, as the signal passes through the ionosphere, systematic errors that are frequency dependent are introduced, so it is not possible to directly convert from one carrier phase value to another for a specific range measurement. The error is known as the ionospheric residual, and this will change slowly over time as the satellite passes overhead and the ionosphere being passed through changes, and also as the ionosphere slowly changes its characteristics over time, mainly due to the sun’s activities.
Equation 2 shows the calculation, using L1 and L2 carrier phase readings and corresponding frequencies, used to calculate the ionospheric residual. Again, the difference in the ionospheric residual values between adjacent epochs is used, as in the same way as the range residual values, external noise sources are eliminated.
(2)
Results
The results presented here are a subset of a much larger set. Figure 1 illustrates the range residuals for L1 and L2 as well as the L1L2 ionospheric residual for PRN32 (Block IIA satellite).
Figure 1. L1 range residual (left) L2 range residual (center) and L1L2 ionospheric residual (right) for GPS PRN32 (Block IIA) satellite. (Charts: Authors)
Figure 2 illustrates the L1 and L5 range residuals and the L2 (C-code) L5 ionospheric residual for PRN01 (Block IIF satellite).Both figures’ data are for the complete passing of the satellites from horizon over and back down again.The data for PRN32 is all that exists in the datafile, as this satellite only transmits L1 CA code and P(Y) code, as well as L2 P(Y) code, and corresponding carrier values.
Figure 2. L1 range residual (left) L5 range residual (center) and L2 (C code) L5 ionospheric residual (right) for GPS PRN01 (Block IIF) satellite. (Charts: Authors)
PRN01 is a block IIF satellite, and data for L1 CA code, L2 P(Y) code as well as L2 C-code, L5 code, and corresponding carrier phase values are recorded in the datafile.The block IIF satellites can result in four range residual values and five ionospheric residual combinations.Figure 2 only illustrates three of these combinations.The data were obtained from the Curtin University GNSS repository on Sept. 1, 2015, gathered at a 1-Hz epoch interval; 29,908 epoch of data were gathered for PRN32, and 26,073 epochs for PRN01.
It can be seen from these figures that the L1 range residuals are similar in characteristics for both PRN01 and PRN32.The values are noisy at the start and the end of the time series, indicating that the CA code is more prone to noise at low elevations.Comparing these to the L2 (PRN32) and L5 (PRN01) range residuals, we can see that both the L2 and L5 range residuals are not as prone to low elevation noise. Also, the two L2 and L5 range residuals are visually similar in characteristcs.By comparing the L1L2 and L2L5 ionospheric residuals (Figure 1, right, and Figure 2, right), we can see that the L1L2 combination is slightly noisier than the L2L5, in particular at low elevation angles.
If we compare BeiDou ionospheric residual results, we can see the comparison of noise on the three ionospheric residual combinations, B1B2, B1B3 and B2B3, as well as the results from the three types of satellite orbits, ie MEO, IGSO and GEO. Figure 3 illustrates the ionospheric residual results for PRN07 (IGSO) for the three frequency combinations, from data gathered on a static pillar located on top of the University of Nottingham Ningbo China’s Science and Engineering Building.
Figure 3. Ionospheric residual results for BeiDou PRN07 (IGSO) for combinations B1B2 (left), B1B3 (center), B2B3 (right). (Chart: Authors)
Figure 4 illustrates the ionospheric residual results for PRN01 (GEO) for the three frequency combinations.
Figure 4. Ionospheric residual results for BeiDou PRN01 (GEO) for combinations B1B2 (left), B1B3 (center), B2B3 (right). (Chart: Authors)
Figure 5 illustrates the ionospheric residual results for PRN12 (MEO) for the three frequency combinations. Here it can be seen that the B2B3 combination is generally less noisy than the B1B2 and B1B3. In addition to this, it can be seen that when the MEO and IGSO satellites are at lower elevation angles, the observables also become noisier. The GEO satellites have a constant elevation angle, and do not experience this phenomenon.
Figure 5. Ionospheric residual results for BeiDou PRN12 (MEO) for combinations B1B2 (left), B1B3 (center), B2B3 (right). (Charts: Authors)
Detailed Results
The data, gathered on a single GNSS receiver located at the University of Curtin’s GNSS research center, was downloaded in BINEX format and converted into RINEX 3.02 format using RTKLIB software. Software was developed by the authors in Matlab in order to interrogate the data files and implement the range residual and ionospheric residual algorithms. RINEX 3.02 format was chosen due to its compatibility with multi-GNSS and multi-frequencies.
Industrial UAV applications such as construction draw benefits from multi-GNSS receivers’ capabilities. (Photo: Skycatch, Swift Navigation)
Results are presented for both ionospheric residual and range residual results for various GNSS. These results have been calculated with varying elevation mask angles, ranging from 0° to 55° at 5° intervals. The RMS values of the resulting ionospheric residuals and range residuals were calculated and plotted against the respective elevation mask angle for each satellite and frequency combinations. This illustrates the influence of the elevation mask angle used on the results.
Typically, tens of thousands of epochs of data were used for every plotted point in the following figures. Further to this, not only are the results for the various frequencies and frequency combinations for the various GNSS illustrated, but also the various satellite types, MEO, GEO and IGSO, and various satellite Blocks for GNSS. GPS Block IIA (PRN04 and PRN32), Block IIR (PRN14), Block IIR-M (PRN31) and Block IIF (PRN01, PRN26, PRN25) data were all analyzed. Thus, the comparison of the various frequencies within each satellite system are illustrated, as well as the variations by comparing the various satellite constellation types and the various generations of GPS satellites.
Surveying accuracy is critical to roadway construction. (Photo: Leica Geosystems)
The BeiDou data illustrated are MEO (C12, C14, C11), IGSO (C09, C10, C07) and GEO (C01, C02). The data used were gathered on Sept. 1, 2015, in order to include GPS Block IIA satellites (PRN04 and PRN32). PRN32 was retired in June 2016, and PRN04 was taken out of active service in November 2015, but the satellite was reactivated in March 2018, this time broadcasting PRN18.
Figure 6 illustrates RMS of the range residual results for GPS (a), BeiDou (b), Galileo (c), GLONASS (d) and QZSS (e) respectively. These figures have been drawn so that the y-axis ranges are the same for each, hence illustrating the relative values.
Figure 6A illustrates the range residual results for GPS. It can be seen that the L1 CA code results are the noisiest, with PRN14 being the noisiest, followed by PRN31, PRN26, PRN01, PRN04, PRN25 and PRN32. It can also be seen with these results that lower elevation angle mask increases the noise level. Both the L2 and L5 code results are less noisy.
Figure 6A. RMS range residual results for GPS. (Chart: Authors)
Looking at the detail, the L5 code results is less noisy than the L2 and affected less than the L1 results by the changes in elevation mask angles used. Interestingly enough, the data file includes both the L2 P(Y) code and L2C code results. L2C only exists on the Block IIR-M and Block IIF satellites. The L2C code results are generally noisier than the L2 P(Y) code.
Figure 6B illustrates the results for the range residuals for the BeiDou satellites. Here it can be seen that the B1 code is affected more by low elevation mask angles than B2 and B3. It can also be seen that both the geostationary satellites’ B1 results stand out, with satellite C02 being noisier than C01. The B2 and B3 values for both these GEO satellites are bunched up with the majority of the other results towards the middle of the figure. The pairs of B2 and B3 results for the GEO satellites are close to each other in values, and the pairs of B2 and B3 results for the other satellites are also close to each other.
Figure 6B. RMS range residual results for BeiDou. (Chart: Authors)
It can also be seen that the range residual results for BeiDou are generally less noisy than than GPS, in units of cycles.
Similarly, for Galileo, Figure 6C, the E1 results are worst, and affected more by low elevation masks. Again, generally the Galileo results are seen to be improved over GPS. The GLONASS results, Figure 6D, illustrate that the L1C results are generally noisier, and then the L1P, followed by L2C and L2P. PRN09 is also consistently generally noisier than PRN10. Finally, Figure 6E illustrates the results for QZSS. Again, L1C is the noisiest and affected most by low elevation mask angles.
Figure 6C. RMS range residual results for Galileo. (Chart: Authors)Figure 6D. RMS range residual results for GLONASS. (Chart: Authors)Figure 6E. RMS range residual results for QZSS. (Chart: Authors)
Figure 7 illustrates the ionspheric residual results for the same satellites as Figure 6. This time, however, the resulting ionospheric residual values are calculated using pairs of data from the same satellite on different carrier frequencies. The range residual results compare the code and carrier from specific satellites and frequencies.
Figure 7(a) shows that the ionospheric residual results are affected by low elevation masks, and that the L1L2CW (L1 CA code and L2 P(Y) code available on all the satellites) combinations are the noisiest, followed by L2L5WX (L2 P(Y) code and L5 code available on Block IIF satellites, PRN 26, PRN01, PRN25), followed by L1L2CX (L1 CA code and L2 C code available on Block IIF and Block IIR-M satellites, PRN31, PRN26, PRN01 and PRN25), followed by L1L5CX (L1 CA code and L5 code, Block IIF satellites, PRN01, PRN25, PRN26) and finally the least noisy were the L2L5XX results (L2 C code and L5 code available on Block IIF satellites, PRN26, PRN25 and PRN01).
Figure 7A. Ionospheric residual results for GPS. (Chart: Authors)
Figure 7(b) illustrates the BeiDou ionospheric residual plots, illustrating that satellite C14 is much noisier for all three combinations of B1B3, BB1B2 and B2B3 in that order. The B1B2 combinations for the satellites are generally the noisiest, and then the B1B3 and B2B3 combinations are intertwined. The Galileo results again illustrate that the E1 combinations are generally noisier, and again we see the effect of low elevation angle masks, Figure 7(c). Generally, however, the Galileo results are less noisy than GPS, as are the BeiDou results.
Figure 7B. Ionospheric residual results for BeiDou. (Chart: Authors)Figure 7C. Ionospheric residual results for Galileo. (Chart: Authors)
The GLONASS results are again generally the noisiest, and again PRN09 is noisier than PRN10, with the L1P combinations being noisier, Figure 7(d). Figure 7(e) for QZSS shows that there are generally two groups of results. The upper set consists of L1L2ZX, L1L5ZX, L1L2XX, L1L5XX, L1L6ZX and L1L6XX from highest to lowest noise respectively. The lower, less noisy, group consists of L1L2CX, L1L5CX, L2L5XX, L2L6XX, L1L6CX and L5L6XX from highest to lowest noise respectively. Further details about the various codes and carrier values can be found in the RINEX 3.02 manual produced by the IGS.
Figure 7D. Ionospheric residual results for GLONASS. (Chart: Authors)Figure 7E. Ionospheric residual results for QZSS.(Chart: Authors)
Conclusions
A surveyor checks an urban construction project. (Photo: Topcon)
These preliminary results illustrate that there are differences in the noise values for various GNSS, frequencies as well as satellite generations and orbit types. It can be seen that generally L1, B1 and E1 have noisier results, and are affected moreso by low elevation mask data, and hence multipath. It can also be seen that newer generations of satellites do indeed produce better quality data.
Some specific satellites produce lower quality data such as GLONASS PRN09 and BeiDou C14. This could be due to multipath produced at the satellite.
Today roughly 100 GNSS transmit data, and typically users can gather data from 30 to 50 at any time. Positioning requires nowhere near this number of satellites, therefore decisions are needed as to which satellites and which data to use in a positioning solution. Our findings imply that our approach could be used in such decision-making in GNSS processing software, helping the software to choose the optimum satellites to draw from in a positioning solution.
Acknowledgments
This work described in this article was first presented at the FIG 2018 conference held in Istanbul, Turkey. The authors acknowledge the use of data supplied from the Curtin University GNSS Centre.
Manufacturers
The GNSS receiver used is a Trimble NET R9, and the antenna is a Trimble TRM 59800.00 SCIS choke ring antenna. A ComNav K508 GNSS receiver supplied some of the BeiDou results.
GETHIN WYN ROBERTS is an associate professor at Fróðskaparsetur, the University of the Faroe Islands. He is past Chairman of the FIG’s Commission 6, Engineering Surveys, and previously held posts at the University of Nottingham both in the UK and in China. He holds a Ph.D. in engineering surveying and geodesy from the University of Nottingham.
CRAIG M. HANCOCK is an associate professor in Geodesy and Surveying Engineering and the head of the Department of Civil Engineering at the University of Nottingham, Ningbo, China as well as the head of the Geospatial and Geohazards Research Group. He holds a PhD from the University of Newcastle Upon Tyne.
XU TANG is a research fellow at the University of Nottingham, Ningbo, China. He holds a PhD from Nanjing University.
DJI Phantom 4 Pro with Loki PPK system. (Photo: GeoCue)
GeoCue Group (via its wholly owned AirGon subsidiary) has completed the integration of the DJI Phantom 4 Pro RTK (P4R) into its AirGon Sensor Processing Suite (ASPSuite).
ASPSuite is a post-processing solution for GeoCue’s Loki direct geopositioning system for DJI and other manufacturer’s drones.
ASPSuite enables integration of the P4R with third-party L1/L2 GNSS base stations such as systems from Septentrio, Leica, Trimble, Topcon, CHC and others in a high accuracy post-process kinematic (PPK) workflow.
In addition to PPK processing, ASPSuite includes support for options often required in engineering-grade surveys such as:
vertical transforms (such as ellipsoid to country-specific geoids)
creation of and transformation between collection datums and local coordinate systems (site calibration)
application of antenna static and dynamic lever arm corrections
full support for Loki direct geopositioning systems.
The DJI D-RTK-2 base station (optionally available) for the P4R can only be used in RTK mode, and then only if it is being sited on a known location. The D-RTK-2 does not currently allow access to an observation file, preventing it from being stationed using an online positioning service such as OPUS, AUSPOS, Canadian Geodetic Survey services and so forth. An additional consideration in the integration into ASPSuite is that professional surveyors already have the survey kit that they need incorporated into this workflow.
GeoCue is offering camera calibration services for the P4R for customers who wish to do minimal or control-free high-accuracy mapping projects (the DJI “calibration” is an image de-warping algorithm, not a proper photogrammetric calibration). A test of a GeoCue-calibrated P4R using an OPUS-positioned base station and ASPSuite achieved about 4-cm horizontal and 5-cm vertical network accuracy (RMSE) with no ground control points.
The Faro Focus scanner attached to a Stormbee UAV. (Photo: Stormbee)
3D measurement and imaging company Faro has joined with UAV provider Stormbee to offer an integrated airborne 3D scanning solution designed to quickly gather large area data for crash scene documentation, security pre-planning and military applications.
The integrated solution includes the Faro Focus laser scanner, the Stormbee S series UAV and the Beeflex software suite.
The airborne solution enables wide-area scanning missions, such as highways, train infrastructure, and buildings. While these would take days when scanned from the ground, they can now be completed in just hours without interrupting traffic or setting foot in a zone of interest.
The Faro Focus laser scanner. (Photo: Faro)
The solution further enhances productivity by allowing users to capture complex environments where traditionally would be inaccessible to ground based scanning and levels of accuracy and detail from the air with exceptional.
The data can then download to FARO Zone for crash reconstruction, security pre-planning, military reconnaissance.
The Faro–Stormbee airborne solution has no need for control points, meaning is quicker to start scanning an area compared to other lidar drones. Drone pilots can fly with ease as it goes up to 100 meters (328 feet) in the air. With the drone’s integrated redundancy, even if a propeller or battery fails the UAV still flies.
“Stormbee has developed and validated its UAV credibility from real-life testing in the most rigorous environments,” said Liesbeth Buyck, CEO of Stormbee. “As a result, we are confident that this turnkey solution, that includes the Stormbee UAV and the FARO Focus laser scanner, creates a new reliability and quality benchmark for airborne 3D data capture solutions.”
Users can create centimeter-level accurate point clouds directly from the in-flight data. The user-friendly Beeflex software takes little training to use and can be exported directly into Faro Scene or Faro Zone 3D software for further analysis or to combine aerial scans with the detail-rich data from terrestrial scanners.
The Faro scanner can detach from the drone and be used as a terrestrial scanner or even a mobile mapper. This flexibility allows users to use one scanner in the air, on land or affixed to a vehicle.
Combined with Faro’s Focus laser scanner compact design, IP54 rating and laser technology users can scan a vast variety of scenarios, from large areas (railways, cities), areas with no light (tunnels, burned buildings), and hard-to-document areas (cluttered crime scenes, inside dumpsters).
The ZALA Arctic drones are capable of successfully solving both civilian and military tasks, according to maker Kalashnikov.
Russian small arms manufacturer Kalashnikov presented the ZALA Arctic unmanned aerial vehicle (UAV) adapted for work in Arctic latitudes at the eighth international forum, “The Arctic: the Present and the Future,” reports Russian state news agency TASS.
The drone has its own GIRSAM alternative navigation system developed specially for the navigation of both UAVs and the ground-and water-based users amid the suppression or the absence of GPS or GLONASS signals.
The ZALA 421-08M and ZALA 421-16E systems are suited for their operation at freezing temperatures, which makes it possible to carry out numerous surveillance operations and regularly monitor the ice. The ZALA Arctic’s capabilities facilitate oil and gas extraction planning in areas where accurate weather and ice situation forecasts are required, according to the Kalashnikov website.
ZALA drones are equipped with the AIS system capable of detecting and identifying vessels at a distance of up to 100 kilometers, which exceeds the operational range of ground-based equipment. The user of the ZALA Arctic system receives information about each vessel: its name, size, course and speed.
The operators can autonomously live in the Arctic in a specially developed all-weather living module based on a marine 200-feet container. It is also designed for maintenance of unmanned aerial vehicles at the place of their operation.
“ZALA Arctic drones are capable of successfully solving civilian and military tasks for carrying out research in the Arctic zone, providing for the safety of sea shipping and the round-the-clock protection of the perimeters, organizing the full-fledged system of tracking the Arctic coast and territorial waters,” Kalashnikov Group CEO Vladimir Dmitriyev was quoted as saying.
The forum, “The Arctic: the Present and the Future,” organized by the Association of Polar Explorers, took place Dec. 5-7 in St. Petersburg.
As part of ongoing global expansion, Microdrones has merged with Schübeler Technologies. Since its founding in 1997, Schübeler has built a global business by providing advanced fan propulsion jets and lightweight composite materials fabrication.
Offering a full product lineup of robust turbo fans, jets, compressors, pumps, electric motors, carbon fiber and aluminum composites, Schübeler products are designed to withstand extreme conditions and demanding field use. These components provide thrust power and lightweight durability to high-tech applications including UAVs, professional motorsports and heavy-duty outdoor equipment.
Microdrones, founded in 2005, has evolved from a manufacturer of commercial-grade unmanned VTOL aircraft to a provider of fully integrated systems for surveying, mapping, lidar and inspection applications. These systems are being put to use worldwide by professionals in the construction, mining, energy, agriculture and infrastructure trades.
“We make life easier for professionals by offering the full solution; it has proven to be a successful strategy,” said Microdrones President Vivien Heriard-Dubreuil. “Perfectly integrated drones, sensors, software, workflow, training and support is what the market needed. Welcoming the Schübeler team, talent and capabilities to Microdrones delivers new aviation technology and capabilities to our customers in the form of next generation unmanned aircraft.”
As the preferred provider of VTOL solutions to Trimble Dealers worldwide, Microdrones adds a global sales force and distribution network as well as technical centers and production sites spanning seven countries and three continents.
“Merging with Microdrones empowers us to develop and deliver systems where we can best support customers locally,” said Daniel Schübeler, founder and CEO of Schübeler Technologies. “This is a happy homecoming for me and the team that we’ve built over the past 20 years.”
Schübeler was an original founding partner in Microdrones and helped develop the pioneering technology that helped Microdrones gain global recognition for professional VTOL UAVs. He adds, “Both of these companies have enjoyed global growth and impressive technological advancements independently. Merging our talents and teams will yield amazing solutions in the years to come.”
“This is a strategic growth initiative,” explained Francois Gerner, SVP of Corporate Affairs at Microdrones. We are adding technology, IP, talent, strong leadership and investment capabilities that are complementary to both brands. This deal brings us to more than 150 highly skilled employees worldwide, which translates to better products, service and support.”
The merged companies will retain the Schübeler Technologies brand, which commands a niche’ audience of serious aeromodeling enthusiasts. Schübeler Technologies will continue to serve these markets as well as tackle large-scale custom R&D projects related to propulsion and materials.
