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2006 Federal Emergency Management Agency (FEMA) Topographic LiDAR: Cumberland and York Counties, Maine
browse graphic In the fall of 2006, Sanborn Map Company was contracted by Camp Dresser McKee, Inc (CDM) to execute a LiDAR (Light Detection and Ranging) survey campaign in the state of Maine. LiDAR data in the form of 3-dimensional positions of a dense set of masspoints was collected for the 584 sqaure miles of Cumberland and York Counties. This data was used in the development of the bare-earth-classified elevation point data sets. The Leica ALS-50 LiDAR system was used to collect data for the whole survey campaign. The LiDAR system is calibrated by conducting flight passes over a known ground surface before and after each LiDAR mission. During final data processing, the calibration parameters are inserted into post-processing software. Six airborne GPS (Global Positioning System) base stations were used in this project. A new point was set at the Portland Airport (501) The other base stations were set up at National Geodetic Survey (NGS) markers. NGS Monuments 901- PID: OC0229 and 801 - PID: OC0230 are located at the Biddeford Airport. The other existing NGS monuments used in the network are point 701 - PID: AJ2697, located on Bailey Island, point 702 - PID: OC0429, located at Fort Constitution, and point 703 - PID: OC0478 located southeast of York Beach were tied to the other three points to create a GPS survey network. The coordinates of these stations were checked against each other with the three dimensional GPS baseline created at the airborne support set up and determined to be within project specifications. Leica ALS-50 LiDAR Scanner Parameters: Pulse Rate: 50,000 hertz Scan Frequency: 36 hertz Scan Width (Half Angle): 18 degrees Flying Height: 1,200 meters above ground level Flying Speed: ~120 knots