LiDAR (Light Detection and Ranging)
LiDAR technology is rapidly advancing and has proven to be valuable in the fields of terrain mapping, bathymetry, and more.
LiDAR (Light Detection and Ranging) works as an optical analog to RADAR with advantages related to the smaller wavelengths of the laser pulse.
LiDAR ranges in wavelength from ultra-violet (0.3-0.45 um) to visible (0.45-0.70 um) to the infrared (1-15 um), which is at least 1000 times smaller than RADAR. The RADARSAT satellite, for example, has a wavelength of 5.6 cm.
Data
The raw form of data is a set of x, y, z coordinate points. With recent advances, these points can be seen as distinguishable returns. An instrument that would once give only a bare earth model can now differentiate between the ground and bottoms and tops of tree canopies.
The raw data can be processed to remove unwanted areas or features. Outputs such as topographic maps with contour lines can also be derived from LiDAR.
Manipulation
Programs to manipulate LiDAR data include ENVI, ERDAS Imagine, ArcInfo, and ESRI ArcView (with 3D analyst ext.).
Applications
One useful derivation of LiDAR data is the DEM (digital elevation model).
DEMS are displayed in a raster format with a matrix. The DEM has a specified cell size that corresponds to the earth’s surfaces. The cell contains the average elevation of the points within it.
LiDAR can detect much smaller particles than RADAR in the atmosphere (which cannot detect things smaller than cloud particles) and thus can be used for aerosol detection.
Projects
The RSC is planning research projects undertaking the modeling and testing of analytical processing and using more fieldwork to obtain ground-truth measurements
Projects have been completed and are currently underway in terrain classification including Elkhorn Slough and hidden trail identification.
Other future projects include a collaboration with the MOVES institute on LiDAR standards for data structure and visualization tools and modeling new LiDAR analysis tools.
Related Thesis
Identifying Roads And Trails Hidden Under Canopy Using Lidar
Fermin Espinoza-Lieutenant Commander, United States Navy
Robb E. Owens-Major, United States Air Force
September 2007
Advisor: Richard Christopher Olsen
Second Reader: Mark C. Abrams
