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Westchester County acquired LiDAR data,
developed in 2009 through a cooperative project of NYC DEP, NYS CSCIC, and
the USGS. The County received the raw LAS data (ASPRS LAS v1.1) and a 3‐m
terrain dataset (UTM, Zone 18N, meters; Horizontal Datum NAD 83, Vertical
Datum NAVD 88), and converted the 3‐meter‐resolution digital elevation model
to NY State Plane East, U.S. survey feet. Through a contract, the County
will also obtain new products from the LAS data, including updated 2‐foot
elevation contours, and the first countywide digital surface model (DSM).
These data were specified at accuracies required for updating FEMA flood
maps. Collected between April 16 and June 25, 2009, with some re‐flights on
November 29 and December 2, at a nominal 1‐meter point spacing, and a
vertical accuracy of 18.5 centimeters root mean square error (RMSE) or
better.
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