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GIS.NY.GOV

NYS ITS GIS Program Office

Geographic Information Systems Clearinghouse

The following recommendations were compiled by the Standards Work Group (now the Data Coordination, Standards & Clearinghouse Work Group), and have been approved by the Coordinating Body.


Datum and Coordinate System Standard

The intent of this standard is to minimize the effort required to use data collected from various sources in New York State. Specifically, the intent is to minimize the number of datum and map projection/coordinate systems combinations in use. The intent is not to require data providers to convert old data to new coordinate systems, but rather to make clear a preferred set of standards which make sense and provide maximum utility for new technologies.

Datums:

Recommendation:

NAD-83 - Horizontal
NAVD-88 - Vertical

The NYS Legislature has officially adopted NAD-83 (and any subsequent readjustments by NGS). The use of NAD-83 sets the stage for the use of new technologies including GPS, DOQs, and new one meter satellite imagery. Note: the WGS-80 spheroid should be use with the NAD-83 datum.

Coordinate Systems:

Recommendation:

For data at 1:10,000 scale and larger: State Plane, Meters
For data at scales smaller than 1:10,000: UTM Zone 18, Meters

State plane coordinates are most appropriate for large scale applications such as parcel and utility mapping. The state plane coordinate system provides scale distortions of less than one part in 10,000 within any one zone. Smaller scale data sets including 1:24,000 scale quadrangles and digital orthophoto quadrangles should be built on a continuous statewide coordinate system. UTM zone 18 mathematically extended to cover the entire state provides a convenient and appropriate continuous for mid to small scale mapping. The UTM coordinate system provides scale distortions of less than 4 parts in 10,000 inside any zone. UTM zone 18 extended to cover All of New York provides a maximum scale distortion of 15 parts in 10,000 (or a scale factor of 1.0015).