GPS World

Tag: digital terrain model

  • Bluesky 3D building models aid designs for London residences

    Bluesky 3D building models aid designs for London residences

    Image: Bluesky
    Image: Bluesky

    London building-design agency DCSK is using 3D building models from Bluesky to inform the design of high-profile urban residential developments.

    Derived from the most up-to-date and accurate aerial photography, the Bluesky 3D models allow DCSK to place a design within its real-world context, consider sensitive view and vantage points, and communicate ideas to clients, planning authorities and the public.

    DCSK has used a number of models from Bluesky, including a detailed representation of central Birmingham for the design of a 24-storey student accommodation on Lancaster Street.

    “We have always had to consider how a design sits within the existing cityscape and how it will interact with the buildings and infrastructure that surround it,” said James Khamsi, Director of DCSK. “Before geographically accurate computer representations, such as the Bluesky 3D models, were available and affordable, we relied on a combination of site photographs and traditional 2D maps. This was a crude workflow that raised potential concerns about the currency and accuracy of information that was informing both the design and resulting planning permissions.”

    DCSK is using 3D models from Bluesky for projects such as Curzon Circle Student Accommodation and others.Photogrammetrically derived from stereoscopic aerial photography, the Bluesky models are fully rendered and are provided as either wireframe or block models in a format suitable for use in both CAD and GIS software.

    All Bluesky 3D models are supplied with a digital terrain model (DTM) depicting the topography of the underlying surface.

    DCSK imports the Bluesky data into its 3D modelling software Rhino, where it is used to create a background layer for the design. The development site is isolated, and this data removed from the background layer, allowing for the detailed design to be dropped in. The proposed development can then be viewed and analyzed in its real-world context with detailed assessments of access ways and viewpoints, for example.

    “The Bluesky models allow us to inhabit the site and experience the design as if we were there,” said Khamsi. “We can explore potential sensitivities, and, as the models are agile, we can massage the design exploring different options without leaving the office. The Bluesky models are also intuitive and therefore easy to interpret allowing us to communicate complex design ideas.”

  • 3 keys to successful canopy penetration

    3 keys to successful canopy penetration

    Sunlight through a tree canopy. (Photo: RedTail)
    Sunlight through a tree canopy. (Photo: RedTail)

    RedTail Lidar System’s RTL-400 delivers the trifecta

    Summer is here, and with it comes the challenge of creating accurate topographic maps under tree canopies. The adoption of drone-based, 3D light detection and ranging — or lidar — is emerging as the go-to sensing technique to meet this challenge consistently, safely and cost effectively.

    Designed specifically for use on small drones, the RTL-400 from RedTail Lidar Systems was developed with technology licensed from the U.S. Army Research Laboratory (ARL). The RTL-400 is designed to provide high-resolution 3D images of objects on the ground, flying at an altitude of up to 400 feet.

    The RedTail team recently partnered with the West Virginia Department of Environmental Protection (WVDEP) Division of Mining and Reclamation to demonstrate the RTL-400’s ability to generate an accurate digital terrain model (DTM) under “leaf on” conditions. This can be challenging, because pulsed laser light needs to reach the ground to generate laser light ground returns.

    RTL-400 flight specifications: speed -18 mph, flight time -12 minutes, acreage -20. (Image: RedTail)
    RTL-400 flight specifications: speed -18 mph, flight time -12 minutes, acreage -20. (Image: RedTail)

    One mission of the WVDEP Division of Mining and Reclamation is to assure compliance with the West Virginia Surface Mining and Reclamation Act and other applicable state laws. This task requires ongoing monitoring, mapping and assessment of sites across the state that are actively being reclaimed.

    Originally utilizing photogrammetry to generate point clouds, the WVDEP was unable to create the accurate, under-canopy DTMs that they desired. Looking for an alternate method, they began to consider lidar.

    The RedTail lidar team met with WVDEP representatives at a mine reclamation site in a remote area of south-central West Virginia. The terrain was a mixture of rolling hillside covered with grasses, brush and tree stands.

    The RTL-400 demonstration flight mapped approximately 20 acres of the reclamation site in 12 minutes, flying at an altitude of 196 feet and a speed of 18 mph.

    Once the data was collected, a digital terrain model (DTM) was created, revealing the RTL-400’s ability to generate the high-resolution, high-density point cloud needed to accurately map the terrain beneath the tree. 

    Digital terrain model (DTM) generated from RTL-400 point cloud. (Image: RedTail)
    Digital terrain model (DTM) generated from RTL-400 point cloud. (Image: RedTail)

    The RTL-400 delivered all three key elements needed to provide DTMs in foliated areas:

    • a small beam divergence of 0.5 milliradians (.03 degrees) with a spot size of just 2 inches diameter at the canopy cover
    • the ability to analyze up to five returns from every transmitted pulse so that returns from the ground can be received and processed
    • a pulse density of 800 pulses in every square meter of the canopy (for the WVDEP flight).  
    RTL-400 generated digital terrain model (DTM) overlaid with contour map. (Image: RedTail)
    RTL-400 generated digital terrain model (DTM) overlaid with contour map. (Image: RedTail)

    RedTail Lidar Systems is a division of 4D Tech Solutions Inc., a company focused on providing innovative technology-based solutions to address government and commercial customer needs. RedTail’s in-house technical expertise — coupled with a full suite of software and hardware design and manufacturing tools — allows the company to develop custom lidar solutions for manned and unmanned vehicle applications.

  • Exploring Shetland’s uninhabited Kame of Isbister with GNSS and UAV

    Exploring Shetland’s uninhabited Kame of Isbister with GNSS and UAV

    The mysterious and fascinating Kame of Isbister is situated in Shetland’s north mainland near the North Roe. The location has been studied several times, including by the Extreme Archaeology TV series in 2003. The uninhabited grassland continues to attract explorers because of a series of secret structures.

    Those structures are hidden on the sea-faced slope and can’t be seen from the land nearby. One theory posits that it’s an eremitical monastery settlement. The late Pictish/early Medieval site is hard to access — and that’s where drones coupled with GNSS receivers helped explorers.

    In 2019, Shetland Flyer Aerial Media in collaboration with Shetland College UHI and the Institute for Northern Studies explored the site. Their goals: create a 3D model of the headland as well as an orthomosaic and digital terrain model to identify and map the monastery structures.

    Because the site is hard to access, the team decided to use the DJI Phantom 4 RTK SUA (drone and base) with two flights. One flight captured both the Kame and a piece of the mainland for context, with a ground sample distance (GSD) of 2.4 centimeters/pixel (cm/px). The second flight was on a shorter GSD of 1.9 cm/px to capture detailed pictures of the cape and structures.

    Before the survey, the team used the Emlid Reach RS+ real-time kinematic (RTK) receiver to identify and establish the base mark for the drone on the mainland nearby.

    Ground control point locations. (Image: Emlid)
    Ground control point locations. (Image: Emlid)

    The base mark was then post-processed using data from the OS Net reference station in Lerwick. Considering the long baseline (52 kilometers), it took the team four hours to observe the mark with Reach RS+. Later, when the archaeologists managed to climb the headland, the RTK receiver collected several noticeable control points.

    Creating the 3D model. During both flights, the drone’s base was sending corrections in RTK mode. In post-processing, horizontal accuracy of the processed map initially was within 10 cm with vertical at 15 cm. After adding the control points gathered with the RTK receiver, the error was reduced to 6.5 cm, significantly increasing the accuracy of the model.

    The team performed the GIS processing in QGIS 3.4 LTR.

    Screenshot: Emlid
    Screenshot: Emlid

    Despite the long grass, they managed to distinguish each structure out of the orthomosaic using the 32-bit floating point raster digital elevation model (DEM). The team created a basic map with structures and contours, a hillshade version and a heat map.

    With proper preparation and setup, a GNSS RTK receiver with a drone can gather enough high-accuracy data to create accurate models and maps of an archaeological site — even if it’s hard to reach.

    Shoreline contours and structures. (Image: Emlid)
    Shoreline contours and structures. (Image: Emlid)
    Shoreline contours and structures with hillshade. (Image: Emlid)
    Shoreline contours and structures with hillshade. (Image: Emlid)
    3D model: The heatmap of the Kame of Isbister shows elevations and the archaeological site. (Image: Emlid)
    3D model: The heatmap of the Kame of Isbister shows elevations and the archaeological site. (Image: Emlid)

  • SimActive updates Correlator3D for mining

    According to SimActive, users can now process raw data, produce point clouds and digital surface models, and perform volumetric calculations with the Correlator3D workflow. (Photo: SimActive)
    According to SimActive, users can now process raw data, produce point clouds and digital surface models, and perform volumetric calculations with the Correlator3D workflow. (Photo: SimActive)

    SimActive has updated its Correlator3D end-to-end photogrammetry software to include tools for users to generate precise statistics on mining activities, with improved volumetric calculation.

    The integrated tools allow users to generate precise statistics on mining activities.

    The Correlator3D software performs aerial triangulation and produces dense digital surface models, digital terrain models, point clouds, orthomosaics and vectorized 3D features.

    Applications like mineral extraction monitoring can be done seamlessly within the software.

    Users can process raw drone data, produce point clouds and DSMs, and perform volumetric calculations in the same Correlator3D workflow.

    “Our clients often require project delivery within 24 hours”, said Jennifer Waugh, principal at Alietum Ltd., a Canadian company using unmanned technology to support construction, consulting and government clients. “SimActive enables us to meet this demanding turnaround time.”

    Based in Montreal, Quebec City, Canada, SimActive has been a developer of photogrammetry software since 2003.

  • SimActive launches free data-processing service using Correlator3D

    SimActive Inc., a developer of photogrammetry software, is offering a new free data-processing service using Correlator3D.

    New users can upload their first UAV, satellite or aerial image project to obtain digital surface model (DSM), digital terrain model (DTM), point cloud and orthomosaic outputs.

    Along with optimal results, users also receive tailored feedback, recommendations and training from SimActive experts.

    The service requires no obligation, and is based on Correlator3D software, building on more than a decade of innovation on computer vision algorithms, a subfield of artificial intelligence. Quick turnaround is also possible due to the speed of the software and extensive use of GPU.

    “Our new offer is unique to get the best possible results from the very first project onward,” said Philippe Simard, president of SimActive. “Following this, users are trained with industry-leading technology, custom advice and necessary knowledge for successful mapping.”