1. Week Thirteen Light Detection and Ranging (LIDAR)

2. Lidar principles Lidar R = ½ tc Night scanning Water penetration
Color drape (during day)
For DEMs

3. Lidar principles Early: transects under planes
Modern: scanning mirrors
Lidar creates masspoints arranged by time
Sampling densities vary from 1 pt. / 20 m2 to 20 pts. / 1 m2

4. Lidar principles System requirements
Laser scanner - generates laser pulses and time the reflections
GPS - provides positioning using differential GPS
Inertial measurement unit (IMU) measures angular motion and velocity data and corrects errors
A computer ensures each individual component is performing correctly

5. Lidar principles Lidar makes fantastic DEMs
Digital surface model (DSM) – features on surface
Digital terrain model (DTM) – bare earth only

6. Lidar principles Satellite platforms:
German Aerospace Center – methane lidar 2012
ICESat Geoscience Laser Altimeter System (GLAS) – decommissioned in Aug., 2% of earth’s forests
ICESat II – 2015 launch
Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO)

7. Multiple returns Airborne platforms use single and multiple returns
depends on what instantaneous laser footprint sees (1st return and 2nd return)
93% or more lost in trees
veg. removal filters
manual edit

8. Multiple returns

9. Lidar principles Airborne platforms: http://www.lidarmapping.com/
gss/lidar
and many more…

10. Just points - pre-interpolation
Masspoints to surfaces

11. Just points - pre-interpolation
Masspoints to surfaces

12. Just points - pre-interpolation
Masspoints to surfaces

13. Just points - pre-interpolation
Masspoints to surfaces

14. Interpolation
Masspoints to surfaces

15. Interpolation
Masspoints to surfaces

19. Laser intensity What exactly is returned by laser?
Return looks panchromatic… but it’s not
Trees scatter laser (look dark)
Grass and bare earth reflect (look light)
“there are no rigorous guidelines about how to interpret lidar intensity images” – pg. 345

20. Laser intensity

21. Laser intensity

22. Terrestrial lidar (laser scanning)
ScanStation C10

23. Terrestrial lidar (laser scanning)

24. Terrestrial lidar (laser scanning)

25. Terrestrial lidar (laser scanning)

26. Terrestrial lidar (laser scanning)

27. Terrestrial lidar (laser scanning)

28. Some applications
Figure from:
Also: archaeology, historical preservation, landslide and geomorphic feature mapping, engineering, real estate, clear air turbulence detection, virtual tours, cave mapping, wind farms, adaptive cruise control and vehicle city safety