1. LiDAR Range (R) recorded as R = c * t/2 Unaffected by clouds above
c= speed of light
t = time for signal to send and return
Unaffected by clouds above
100,000 pulses of light / second
Data are generated as a ‘cloud’ of millions of points

2. Early systems recorded only the first return
System threshold separates a real return from noise

3. LiDAR Can create: 1. High resolution DEMs: - 10cm Open gentle terrain
- 50cm Forested or steep terrain
2. Vegetation layers
The only RS device to record multiple layers
Can record bare earth and/or vegetation layers
LiDAR is mostly airborne but some spaceborne

4. Applications Detailed topographic mapping
Coastal areas – change / flooding
Linear disturbance – pipelines, power lines
Geological fault lines
Landslides
Forestry – biomass, canopy height, leaf area
Bathymetric – depth and surface layer biomass
3D urban mapping
Glacier elevation and change
Atmospheric – clouds, gases
Most common wavelength:    1064 nm (Near IR)
Bathymetric surveys: nm (green)   

5. LiDAR – 1064 nm, 532nm, 355nm - why those wavelengths ?
(Not solved by google or LiDAR marketing companies)
Lasers produce light the same way as a neon sign – a substance is stimulated to an excited state, causing the release of extra energy as a photon of light.
Nd:YAG (neodymium-doped yttrium aluminium garnet) is a crystal that is used as a lasing medium for solid-state lasers. It emits at a wavelength of 1064 nm.
According to the Planck-Einstein equation:
Where h= Planck’s constant, and c = the speed of light, halving the wavelength, has the effect of doubling the energy released, and one-third the wavelength (355) triples the energy (= the second and third harmonics)
Solved by Patrick Daley, GEOG432

8. Layers in the data cloud N.Coops, UBC

9. DEMs: Bare Earth and Canopy

10. San Andreas Fault zone

11. TRIM versus LiDAR

12. LiDAR – ice surfaces

13. UNBC area

14. University Hill

20. LiDAR vegetation data in 3D: ALRF
500m x 500m ~ 1,000,000 points

21. Raw Point Files For individual tree analysis (FUSION/LDV)
Elevation of lowest point
675.21m ASL
Elevation of highest point
707.87m ASL
Tree Height ~ 32.66m
Crown Shape ~ Convex (umbrella)
Crown Footprint ~ 11.55m
These points can be used in analysis directly
In this image I’ve zoomed into the points that describe a riverside tree

22. Canopy Height = Canopy Surface – Bare Earth
Canopy Surface Model
Each cell in a canopy surface model details the elevation of the highest feature within that cell
Height is more practical than elevation for describing vegetation
Canopy Height = Canopy Surface – Bare Earth

23. Canopy Surface Model

24. Canopy Height Model

25. Canopy Surface Model

26. Stand Level Vertical Return Density Schematic
of a 20m x 20m LiDAR Point Cloud – 400 Pulses
Histogram of Returns (percent)

27. Stand Level Vertical Return Density Schematic
of a 20m x 20m LiDAR Point Cloud – 400 Pulses
Histogram of Returns (percent)

28. Stand Level Vertical Return Density Schematic
of a 20m x 20m LiDAR Point Cloud – 400 Pulses
Histogram of Returns (percent)

29. Tree Stem Maps
Individual tree crowns are discernable from the Canopy Height Model so we developed a tree finding algorithm to identify tree stem locations

30. Tree Stems (displayed by tree height)

31. LiDAR Data (by crown size)
Vegetation Data Products
LiDAR Data (by crown size)

32. Tree Stems (displayed by crown shape)

34. http://www-lite. larc. nasa. gov/n_the_images
LITE: Lidar In-space Technology Experiment Sept 1994

35. ICESat (Ice, Cloud,and land Elevation Satellite) 2003-2009
GLAS (Geoscience Laser Altimeter System) is the first laser-ranging (lidar) instrument for continuous observations of Earth
Orbits at 600km at 94 degree angle (covers 86N – 86S), lasers:
infrared light (1064 nanometers) for topography and dense clouds
visible green light (532 nanometers) for clouds and aerosols
Laser pulses illuminate spots (footprints) 70 metres in diameter, spaced at 170-metre intervals along Earth's surface.

38. Greenland

39. Antarctica - IceSat

40. Amazon - IceSat

41. IceSAT vegetation

42. Mars Orbiter Laser Altimeter (MOLA)
-on the Mars Global Surveyor spacecraft. It collected altimetry data about the height of surface features on Mars from
Data collected at 1064 nm – Vertical res. 37cm (~1 foot)
This is a pole-to-pole view of Martian topography from the first MOLA global topographic model. The slice runs from the north pole (left) to the south pole (right) along the 0° longitude line. The south pole has a higher elevation than the north pole by ~6 km. This global-scale slope controlled the surface and subsurface transport of water indicated by outflow channels and valley networks.
Discoveries e.g seasonal snow:

43. MOLA images http://mola.gsfc.nasa.gov/images.html