a Geo-Odyssey of UAS LiDAR Mapping Henno Morkel – UAS Segment SpecialistDroneCon – 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

¹ Source - https://en.wikipedia.org/wiki/Lidar

Airborne 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 open-

cast 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 June2018

§ Anyone who is interested aremore than welcome, andplease come and chat with usat our stand number. 14 in theDroneCon 2018 dome

Thank you for your time and attention

Safe Flying!!