This dataset covers the geographic area of Westchester County, New York. Dataset contains planimetric base map data for major lakes. It is a derivative of bmlakes.
The source for the imagery is aerial photography acquired in April 2004. The planimetric data was originally compiled from aerial imagery collected in the year 2000. In 2004, new aerial imagery was acquired over the county of Westchester and all planimetric data was updated at that time. This layer contains the polygons delineating hydrologic features. The data was photogrammetrically stereo-compiled to North American Datum 1983; New York State Plane East Zone. Image horizontal accuracy is +/-2.5 ft. at the 90% confidence level.
The aerial photography and creation of the subsequent planimetric data was executed to capture the existing ground conditions at a specific point in time for the purpose of GIS analysis. A GIS is a system of computer software, hardware, and data that allows a user to manipulate, analyze, and present information that is tied to a spatial location. GIS technology is used in scientific investigations, resource management, development planning, and many other applications that require analysis of spatial data. Planimetric base map data along with digital orthophotography typically provide an accurate base for digitally representing geographic features upon which the GIS is built.
Westchester County Geographic Information Systems (GIS) develops, maintains and distributes digital data for Westchester County, New York. County GIS staff also supports GIS applications and programs in both county and local governments.
The aerial film was acquired in April 2004. The imagery was scanned at 14 microns using a Z/I Imaging PhotoScan 2000 scanner. The ground control used to support the planimetric base mapping was collected by either paneling of permanent monuments or photographic identification of strategic points. The coordinates were collected via ground survey techniques and the Aerial Triangulation was performed using Zeiss ISAT software. The final bundle adjustment was performed using PAT-B software. The planimetric data were updated from photogrammetrically compiled features produced for Westchester County in the year 2000. All new stereo-model images were reviewed on first-order softcopy stereo plotters for changes to the planimetric features.