Proj.NET and 102100 Projection

Question

I am using the ProjNET library to do reprojection in the client for popular coordinate systems. When I try to specify 102100 as a destination coordinate system (using several variant WKT's), the points always have a y-error of about 20km (in SoCal). Is there anyone out there who has successfully modified this library (I'm guessing with a shift grid) to support 102100 as a destination? I really would like to be able to drop the ESRI.ArcGIS.Client.Bing.dll from my project references!

Thanks,
Dan

DanielWalton · Answer

Yes, all my test cases use the WGS84 datum. Using the Bing assembly they all visualize correctly over a 102100 map service, and with ProjNet they all show up 20km south.

Thanks,
Dan

SomeGISGuy · Answer

No it's not able to do a datum transform. The input MUST be EPSG:4326, or it will throw an exception.
http://help.arcgis.com/en/webapi/silverlight/apiref/topic2392.html

DanielWalton · Answer

Are they all using the WGS84 datum? If not, I don't think you will have much luck with anything but the projection service.

Why not? Obviously the ESRI.ArcGIS.Client.Bing library is able to do this in the client. Is it proprietary ?

Thanks,
Dan