Coordinate Systems General Information

Coordinate Systems Frequently Asked Questions

Q: What software package is used to perform coordinate conversion?

A: We use the public domain PROJ.4 Cartographic Projections library to perform coordinate conversion.

Q: How are datum shifts determined when converting between NAD27 and NAD83 in Canada?

A: We automatically selectsthe NTV2 datum shift file when converting Canadian coordinate systems data.

Q: How are datum shifts determined when converting between NAD27 and NAD83 in the United States?

A: We use the NADCON "conus" file for the continental United States and the NADCON "Alaska" grid shift file for Alaska datum shifts.

Q: When performing coordinate conversions between different coordinate systems are coordinates first converted to WGS 84?

A: No. Datum shifts are specified in reference to WGS 84 but conversions are performed directly between coordinate systems.

Also See

• Select Coordinate System