Survey / Mapping
Drones are increasingly important and efficient tools for conducting precision surveys and accurate 2D and 3D renderings of land, buildings, and other structures.
For many years drones have been used for photogrammetry – the science of making measurements from photographs. The input to photogrammetry is images and the output is a point cloud typically rendered as a map, a drawing, measurement, or a 3D model of some real-world object or scene. Aerial drone-based photogrammetry has been aided in the past several years by embedding GPS data in the metadata of the images. Post processing software (such as DJI Terra) uses the GPS data to help stitch the images into a Topographical or Orthomosic map (see below). To increase the accuracy of the maps, Ground Control Points (GCP’s) are used as reference points and loaded in the post processing software along with the images. Historically, the more GPC’s used, the more accurate the map.
Picture provided by Prof Jason T Herrmann, University of Pennsylvania.
The progression of technology through higher resolution cameras (see Zenmuse P1) and more accurate positioning systems such as RTK (Real Time Kinematics) has allowed Surveyors and Engineers to obtain higher quality and more precise maps with fewer GCP’s, greatly lowering costs and improving the efficiency. For the past several years, far and away the most popular RTK mapping system has been the DJI Phantom 4 RTK.
In contrast to photogrammetry, Light Detection and Ranging (LIDAR), a technology similar to RADAR, can also be used to create high-resolution point clouds with a high degree of accuracy. With LIDAR, laser beams are used to accurately measure distances between objects. The return signal is processed, and a point cloud is created. Using post processing software such as DJI Terra, digital maps (Topo’s and Ortho’s) can be created.
Full color RGB point cloud from Zenmuse L1 Lidar system.
Photogrammetry vs Lidar
Photogrammetry and Lidar point clouds both have advantages and disadvantages. The one most suitable depends on the specific application. Historically, there had been one difference that distinguished photogrammetry from Lidar and that is RGB. Photogrammetric point clouds have an RGB value for each point. This results in a colorized map. Traditional Lidar systems only provide x,y,z point clouds. The Zenmuse L1 Lidar system overcomes this limitation by pairing an RGB camera with the Lidar – overlapping the point clouds providing both Lidar and photogrammetry advantages.
Insensitive to ambient light. Lidar works equally well in bright light and total darkness.
Foliage penetration. Multi return Lidar sensors use reflected light to “see through” foliage not totally blocking the laser beams.
Can typically cover and process more area in a shorter time span.
Edges can be sharper therefore provide for more accurate measurements.
Does not require contrast.
RGB full color point clouds
Sensors are smaller and lighter weight
P1 Survey Camera
L1 LIDAR Camera
- 45MP Full-frame Sensor
- 4.4μm Pixel Size
- Low-noise, high sensitivity imaging extends daily operational time
- Take a photo every 0.7 s during the flight
- TimeSync 2.0 aligns the camera, flight controller, RTK module, and gimbal at the microsecond level
- Frame Lidar with up to 100% effective point cloud results
- Detection Range: 450m (80% reflectivity, 0 klx) / 190 m (10% reflectivity, 100 klx)
- Effective Point Rate: 240,000 pts/s
- Supports 3 Returns
- Line Scan Mode and Non-repetitive Scan Mode
AEC and Surveying
Energy and Infrastructure
Agriculture and Forestry Management
AEC and Surveying
Natural Resource Management
Disaster Site Modeling
DJI’s UAV platforms allow GIS professionals to quickly collect geo-referenced aerial images. All DJI platforms geo-tag images with GPS information which can be processed with photogrammetry to produce point clouds, orthomosaics, and digital terrain models. Prior to UAVs, such mapping could only be achieved by aircraft.
Now, mapping technology is drastically more accessible, allowing individuals and organizations to capture and document the world around them. For the highest accuracy data, we recommend you utilize ground control points (GCPs) when capturing your data. You can then tag the GCPs during processing to produce outputs with centimetre accuracy.
Resource extraction firms today face intense pressure from low commodity prices and regulatory pressures. Operational efficiency is fundamental to sustaining sites through difficult market conditions, and data captured by UAVs can provide fundamental insights. Rapid surveying with ground control points (GCPs) allow for <1cm accuracy data capture.
Automated stockpile calculation and slope grading provides invaluable real world data on operational output, as well as equipment fuel consumption costs in quarries. DJI’s software development kit allows firms to build powerful applications, such as autonomous LiDAR tunnel inspection with an M100. Such applications greatly increase not only increase safety, but also represent significant cost savings on exiting methods.
Environmental Surveying with DroneDeploy
UAV platforms allow GIS professionals to quickly collect geo-referenced aerial images. All DJI platforms geo-tag images with GPS information which can be processed with photogrammetry to produce point clouds, orthomosaics, and digital terrain models. Prior to UAVs, such mapping could only be achieved by aircraft.
DJI and Datumate Map Historical Site in Record Time.