Extraction of digital elevation models for airborne laser terrain mapping data

Topographic information can now be derived from a variety of approaches and instruments, including interferometric SAR, optical and radar stereo, and laser altimetry. Extraction of actual terrain in vegetated areas is a difficult problem for all sensors. The small footprint of the airborne laser terrain (ALTM) data coupled with the potential for acquiring multiple returns for each outgoing pulse now offers new potential for obtaining more accurate digital elevation models (DEMs) which are critical for many applications such as hydrology and shoreline mapping. An Optech 1210 airborne laser terrain mapping instrument was flown over the Kennedy Space Center (KSC) in summer 1999 for the purpose of generating a high resolution DEM of the space complex and the extended wetland environs. Features such as relict dune ridges and swales, impoundment dikes, and man-made features are all clearly visible in the DEM. However, the data exhibited inter-flightline biases and cross track artifacts. New processing techniques are under development to remove anomalies, geometrically correct the data, and extract the vegetation signature to produce the "bald Earth" topography.