Lidar surveys of Assateague Island National Seashore from 1998-2012

Assateague Island National Seashore

The data discussed in this document are grid elevation data derived from Lidar surveys of Assateague Island National Seashore (ASIS). Lidar is a form of topographic mapping which uses a pulsed laser ranging system mounted onboard an aircraft to take high density ground elevation measurements. This data is collected by NASA and sent to USGS for conversion to GeoTiff images (see supplemental information). The images are then sent to the NPS where they are converted into a single grid for use in an ArcGIS software environment. This file contains some information on the types of Lidar data that have been collected on ASIS from 1998-2004. The first surveys collected are referred to as "first return", and were collected by an Automated Topographic Mapper (ATM) system. "First return" Lidar gives a accurate measurement of elevation within +/- 15cm. but it cannot penetrate treetops, other vegetation, or water. The second type of Lidar data was developed much more recently and is referred to as EAARL (Experimental Advanced Airborne Research Lidar). EAARL has the ability to penetrate vegetation and give accurate elevation readings for "first return" and "bare earth". EAARL surveys were first flown on ASIS in September of 2002. More detailed information on these sensors can be found at this link - http://inst.wff.nasa.gov/eaarl/ - or through contacting ASIS (asis_gis@nps.gov).