TECHNIQUES FOR EXTRACTING INFORMATION FROM LIDAR DATA OF LOW-RELIEF TERRAIN IN LOUISIANA

LIDAR is an acronym for Light Detection and Ranging. LIDAR data is collected using a complex system of airborne instruments and computer processing. Louisiana’s statewide LIDAR project began in 2000 in response to repetitive flood loss rates. The project will eventually image most of the state covering an area of approximately 50,000 sq. mi. and encompassing about 3,500 quarter quadrangles (3.75-minute DEM file size). At the end of 2004, over 1,450 LIDAR quarter quads covering most of south Louisiana as well as the Alexandria area are online at the LSU Atlas web site. Atlas LIDAR data is available for download in four different forms: contour lines, digital elevation models, edited points, and raw points. We have developed algorithms to process this data and extract information related to faulting, subsidence, drainage, and geomorphology. Our algorithms are able to generate images with emphasis on different aspects of the data. Many features not identified on USGS topographic maps can be recognized after processing. The low relief of Louisiana, particularly in coastal areas, presents challenges to the identification of features such as fault scarps. In July 2004, ground inspection confirmed the presence of an approx. 30 cm scarp in southwest Louisiana that had been identified by our software. By tailoring computer algorithms to specific requirements, different views of the same LIDAR data can reveal a variety of information.