Datum transformation from NAD83 to NWS84

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08-05-2010 10:45 AM
SantoshChandru
New Contributor
What transformation method will be best suited to convert the datum from NAD83 to NWS84?
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MelitaKennedy
Esri Notable Contributor
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.

Regards,
Melita
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SantoshChandru
New Contributor
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).
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MelitaKennedy
Esri Notable Contributor
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.

Melita
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RocíoVega
New Contributor
Thanks Melita!!
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BeatrizSánchez
New Contributor
Hello,

I just would like to know if this process is also right for the transformation ED50 to Sphere Emep.

Thank you
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