a Geo-Odyssey of UAS LiDAR Mapping Henno Morkel UAS Segment Specialist DroneCon 17 May 2018
Abbreviations UAS Unmanned Aerial Systems LiDAR Light Detection and Ranging UAV Unmanned Aerial Vehicle RTK Real-time Kinematic PPK Post Processing Kinematic DG Direct Geo-referencing EO Exterior Orientation
LiDAR explained LiDAR is a surveying method that measures distance to a target by illuminating the target with pulsed laser light and measuring the reflected pulses with a sensor. ¹ Airborne ¹ Source - https://en.wikipedia.org/wiki/lidar Mobile Terrestrial
A booming industry
What is the goal? To capture elevation and geographical data for a final mapping product To generate the most accurate digital terrain models and various other 3D models that represents the Earth s surface and features To be able to capture ground terrain data that lies under tree canopies To be able to capture accurate elevation data over a large area, quickly and efficiently
Current methods Airborne LiDAR manned aircraft Airborne photogrammetry manned aircraft Satellite imagery Airborne photogrammetry UAVs Airborne LiDAR UAVs
Surveying and Mapping - Photogrammetry Traditional UAV aerial surveying methods Photogrammetry DSM (Digital Surface Model) generation via stereo-pairing of multiple digital aerial images:
Surveying and Mapping - Photogrammetry Time consuming to set out all of the GCP s (ground control points) for survey grade accuracy Limitation of photogrammetric DSM (Digital Surface Model) is that one does not get data below tree canopies and vegetation to get a truly accurate representation of the ground terrain over a specific area One also needs a lot of image overlap to achieve dense data
RTK - UAV surveying To achieve high accuracy one can either use the RTK (Real Time Kinematic) method together with a GPS system or one can use PPK (Post Processing Kinematic) Normal RTK with base and rover in normal surveying RTK surveying with a base station and your drone is the rover
DG - Direct Georeferencing Ever increasing need to be more accurate and more efficient with UAV surveying new technology Accuracy of UAV captured data is directly related to the positional accuracy of the UAV while it is capturing data With the aid of a Trimble APX-15 UAV highly accurate GNSS receiver, and the IMU (inertial measurement unit) one can achieve very high positional accuracy of your UAV and its sensor
DG - Direct Geo-referencing What is the difference between RTK & PPK versus Direct Geo-referencing technology? The calculation of the orientation angles (EO) of the UAV sensor are not accounted for with RTK & PPK, but they are accounted for with Direct Geo-referencing Thus one does not only get the Easting, Northing, and Elevation positional accuracy of the UAV, but also its orientation angles Omega, Phi, and Kappa
Microdrones UAS LiDAR systems
Surveying and Mapping DG & LiDAR Dr. Mohammed Mostafa a highly distinguished scientist at Microdrones argues that traditional RTK and PPK systems have inherent problems when it comes to accuracy, and that they sacrifice accuracy and quality for speed He also points out that the relative position of a UAV can be more accurately calculated by relying on the UAS s IMU coupled with a high grade GNSS versus the RTK-GPS method
Surveying and Mapping DG & LiDAR With the advent of direct geo-referencing technology together with a LiDAR payload, surveyors and geospatial professionals can capture data and process it in a fraction of the time versus traditional Aerial Triangulation methods Trimble / Applanix APX-15 Single board GNSS-Inertial solution for UAVs
Surveying and Mapping UAS LiDAR The most common applications of UAV LiDAR systems today are for: Corridor Mapping Roads, Railways, Pipelines, Waterways, and Electrical Transmission Lines Mine surveying Volumetric stockpile calculations and opencast Pit designs Coastal mapping Forestry
mdlidar1000
Advantages of Direct Geo-referencing
RTK and PPK versus DG
Conclusion The UAS LiDAR industry has seen huge advancements in the past 4 years in terms of accuracy and longer flight times I personally believe that photogrammetry are not obsolete, and that it still has its rightful place in the aerial surveying and mapping industry The advent of DG coupled with LiDAR technology will open up many doors in the UAS industry going forward
IMPORTANT NOTICE Keep your calendar s open mdlidar1000 demonstration Optron is planning a live UAV LiDAR demonstration in June 2018 Anyone who is interested are more than welcome, and please come and chat with us at our stand number. 14 in the DroneCon 2018dome
Safe Flying!! Thank you for your time and attention