These files contain 2016 digital Ortho-imagery of Westchester County, New York. Image pixel size is 0.5' GSD. Image type is 4-band, RGB & NIR. The Image horizontal accuracy is within 4' at the 95% confidence level (NSSDA). Each file contains an image covering 2000 ft. by 3000 ft. on the ground.
This digital Ortho-imagery can serve a variety of purposes, from general planning to field reference for spatial analysis to a tool for revision of vector maps. It can also serve as a reference layer for GIS.
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NYS ITS GIS Progam Office
TThe New York State Office of Information Technology Services makes no claims to the accuracy of the information in this file. THE GIS DATA IS PROVIDED AS IS AND WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED, AS TO THEIR PERFORMANCE, MERCHANTABILITY, OR FITNESS FOR ANY PARTICULAR PURPOSE. NYS ITS does not represent or warrant that the GIS data is error-free, complete, current, or accurate. The file naming convention was supplied by New York State. When the ortho tiles were created the file names were restricted to a numeric value representing the lower left corner of the ortho tile. These tiles were then all renamed using a batch script so that they reflected the N.Y. state standard (i.e. "l_15510420_06_08200_4bd_2016.tif"). Consistency of file naming was ensured by using a batch process. The file naming convention consists of the first letter for Central, East, West or Long Island for New York State Plane Coordinate Systems (NYSPCS). The following four numeric characters represent the first four characters of the "X" coordinate value for the tile's lower left corner coordinate in NYSPCS and the next four characters represent the first four characters of the "Y" coordinate value for the tile's lower left corner coordinate in NYSPCS. The next two numeric characters represent the tile's Ground Sampling Distance (GSD) value in ft. The following five numeric characters represent the Above Mean Terrain (AMT) nominal height at which the Ultracam X sensor recorded or collected the original imagery for the corresponding area. The next three characters are "4bd" for 4-band ortho-photos. Lastly, the last four numeric digits represent the year in which the particular ortho was created.
The project consisted of 3184 final tiles.
+/-4 ft. at the 95% confidence level (NSSDA) for 6 inch resolution.
The Digital Natural Color aerial imagery was acquired in Spring 2016 using a Microsoft Ultracam Eagle sensor flown at a nominal height of 7400' AMT (Above Mean Terrain). ABGPS data was also collected and processed using POSPac (version 7.3) Mobile Mapping Suite . The Ground Control used to support the 4-band ortho-imagery production was collected by identifying and surveying photo identifiable points (PID), using existing PIDs, and existing aerial targets. The Digital Aerial Triangulation (DAT) was performed, primarily, using softcopy workstations and Vexcel UltraMap coupled with BINGO. Digital Elevation Models (DEM) used for ortho imagery production were supplied by the state and updated as needed using UltraMap mapping software. The images were then ortho-rectified using UltraMap ortho dtm software modules. Color balancing, seamless mosaicking was performed by automatic seam line creation steps, final color balancing and final extractions were also accomplished using this software. A final tile by tile quality control was performed using Adobe PhotoShop software. The imagery product deliverables are GeoTIFF images with embedded header information describing the required projection, pixel size, tile size and other related data and corresponding world files (.tfw). Derivative compressed imagery is also available in JP2000 format.
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