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My title pretty much tells it all..

I have a number of datasets in which I want to batch project from NAD83 Northern Virginia Datum into the correct Web Mercator projection..

When I do a straight re-projection I get an error message.. this tells me that I need to use a transformation of some kind.. I think..

So, here in lies my problem.. as there is not a web mercator projection transformation listed in the geographic transformation I was thinking I would just use a generic one like...

NAD_1983_To_WGS_1984_2 (there are 8 different ones) WGS_1984_Major_Auxillary_Sphere_To_WGS_1984

But I am not sure that is correct.. Which is the correct "geographic transformation"?

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2 Answers 2

up vote 5 down vote accepted

The esri doc on choosing an appropriate transformation is probably what you want. Specifically:

NAD_1983_To_WGS_1984_5: Transformation parameters calculated by the U.S. National Geodetic Survey (NGS) using CORS stations, and ties WGS 1984 to ITRF96. Accuracy according to EPSG is +/- 1 meter.

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Thanks Again!!!! –  Not to be named Sep 29 '10 at 16:27

see http://gis.stackexchange.com/questions/2383/does-re-projecting-an-esri-shapefile-only-update-the-content-of-the-prj-file/2424#2424 for a picture which makes sense of all those words on the help page in 2 seconds.

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