Lidar Processing Systems
ALPS
Post-flight processing of EAARL data is accomplished using a custom-built processing system known as the Airborne Lidar Processing System (ALPS). The ALPS software has been developed in a collaboration between NASA and USGS in an open-source programming environment on a Linux platform. ALPS supports the exploration and processing of lidar data in an interactive or batch mode. Modules for pre-survey flightline definition, flight path plotting, lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the 'bald Earth' under vegetation from a point cloud of 'last return' elevations. Presently, ALPS is in use to support methodological research aimed at the vertically resolved mapping of coral reef habitats. In addition, ALPS is enabling the systematic creation of highly detailed submarine and sub-aerial topographic maps for use in ecological models and environmental stewardship.
Snapshot of the NASA/USGS ALPS system. ALPS is composed of several modules as seen in the image. The data represent an Australian Pine forest in the Terra Ceia region of Tampa Bay, Florida. [larger version]
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LaserMap
LaserMap is a software tool written in Research Systems Inc. Interactive Data Language (IDL) to convert dense lidar data sets acquired by the NASA ATM system into fully documented standard data products that are readily ingested by common surface modeling and GIS software packages such as Erdas Imagine, ArcInfo, or ArcView. The LaserMap package has been designed to run through a menu system to enable scientists to prepare their own data sets with minimal instruction. Data products may be created at several levels to allow for flexibility in further analysis using other software. LaserMap supports reference system conversion, the merging of multiple flight line swaths, the sorting of the surveyed elevations by either latitude or longitude, automatic creation of data documentation at each level, and the creation of ready-to-use binary or ascii point files, full precision grids, and scaled digital elevation images. Once a processing job has been initiated through the menu, all operations are transparent to the user.
For more information, visit: http://soundwaves.usgs.gov/2001/05/research2.html.
Lasermap processing system. |
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