| 2007 Florida Division of Emergency Management (FDEM) Lidar Project: Nassau County |
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This report pertains to a Specific Purpose LiDAR Survey of Nassau County, Florida.
The LiDAR aerial acquisition was conducted by Terrapoint USA between August 18, 2007
and September 4, 2007, and the breaklines and contours were subsequently generated
by Dewberry. The PDS team is under contract HS-34-14-00-22-469 with the Florida Division
of Emergency Management (FDEM) and offered LiDAR and derived products as an add-on
agreement with Nassau County at the same rates as negotiated for the FDEM contract
and utilizing the same Baseline Specifications from FDEM. The LiDAR dataset of Nassau
County was acquired by Terrapoint USA and processed to a bare-earth digital terrain
model (DTM) in accordance with FDEM Baseline Specifications. Detailed breaklines and
contours were also produced by the PDS team. Each tile covers an area of 5000 ft by
5000 ft. The FDEM Baseline Specifications require a maximum LiDAR post spacing of
4 feet, i.e., an average point density of less than 1 point per square meter. However,
the PDS team required a much higher point density of its subcontractors in order to
increase the probability of penetrating dense foliage; with nominal post spacing of
0.7 meters per flight line and 50% sidelap between flight lines, the average point
density is 4 points per square meter with higher point density there is a greater
probability of penetrating dense vegetation and minimizing areas defined as "low confidence
areas." LiDAR was delivered as a point cloud in LAS 1.1 format.
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