What transformation method will be best suited to convert the datum from NAD83 to NWS84?
Do you mean WGS84 also known as WGS 1984? Try NAD_1983_To_WGS_1984_5. If the data is in the lower 48 states (except maybe the west coast states) and accuracy is a meter or more, try NAD_1983_To_WGS_1984.
Do you mean WGS84 also known as WGS 1984? Try NAD_1983_To_WGS_1984_5. If the data is in the lower 48 states (except maybe the west coast states) and accuracy is a meter or more, try NAD_1983_To_WGS_1984.
Regards, Melita
No, I am looking for transformation from NAD1983 to NWS84 (Radius 6370 km spheroid).
No, I am looking for transformation from NAD1983 to NWS84 (Radius 6370 km spheroid).
Ah, I haven't heard of NWS84. There are no transformations from a geodetic datum-based geographic coordinate system to a sphere-based geographic coordinate system.
We do have a GCS already built with a radius of 6370000 m. It's called "Sphere EMEP".
There's a geoprocessing / ArcToolbox tool called Create Custom Geographic Transformation. Use NAD 1983 for the input/from and Sphere EMEP for the output/to. For the method, if you have version 10, use Null. If you have 9.3.1, use Longitude_Rotation.
If you do the conversion and the data is offset strictly north-south by kilometers, define a second transformation. This time use Geocentric_Translation for the method and leave the parameter values set to zeroes, and see if that works better.
