LIDAR Data (Light Detection and Ranging)
Light Detection and Ranging (LIDAR) is a remote sensing technology that can be used to collect both vegetative cover (e.g. forest canopy) and topographic data. Post processing is used to separate vegetative and topographic signals, and the accuracy of the topographic data is somewhat reduced when dense vegetative cover is present. The laser system is usually mounted in an aircraft and flown at relatively low altitude over a region of interest to produce high-resolution data sets. Horizontal resolutions (pixel size) of one meter or better are possible. Due to the manner in which the data is collected, it is often released in the form of irregular (nongridded) XYZ triples, which can then be used to create a raster grid. RiverTools can import LIDAR data in this and other formats.
The National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center is using LIDAR in their Topographic Change Mapping project, in partnership with NASA and the USGS, to document topographic change along shorelines. In this project, data is collected by the Airborne Topographic Mapper (ATM). The ATM collects 3000 to 5000 spot elevations per second as the aircraft travels over the beach at approximately 60 meters per second, or 135 miles per hour. Using the ATM, vertical accuracies of 20 centimeters have been achieved. Elevation data from subsequent flights can be used to quantify changes due to erosion.
The is no single data source, although NOAA collects and shares some LIDAR data on the web. Several private companies can be hired to collect LIDAR data for regions of interest. Another great source of LIDAR DEMs is OpenTopography.org. (See link below).
NOAA has an online LIDAR Data Retrieval Tool (LDART) that allows researchers to share available LIDAR data. Most existing LIDAR data has been collected for specific research projects involving relatively small areas. Many of these are concerned with evaluating the advantages and limitations of LIDAR data.
NOAA LIDAR: http://www.csc.noaa.gov/crs/tcm/index.cfm
LDART web site: http://www.csc.noaa.gov/crs/tcm/ATM_download.cfm
OpenTopography.org web site: http://www.opentopography.org
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