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Proj.NET and 102100 Projection

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06-15-2010 06:42 AM
DanielWalton
Frequent Contributor
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
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6 Replies
dotMorten_esri
Esri Notable Contributor
What is the from coordinate system?
On a side note, webmercator projection will be in the core API at the next release, so you won't need Bing by then (it will also support reprojecting entire geometries and not just points)
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DanielWalton
Frequent Contributor
What is the from coordinate system?
On a side note, webmercator projection will be in the core API at the next release, so you won't need Bing by then (it will also support reprojecting entire geometries and not just points)


Source projections are lat/long (KML) and various Albers projections (shapefiles). They all seem to have the same y-error and all show up fine in 4326.

-Dan
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dotMorten_esri
Esri Notable Contributor
Are they all using the WGS84 datum? If not, I don't think you will have much luck with anything but the projection service.
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DanielWalton
Frequent Contributor
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
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dotMorten_esri
Esri Notable Contributor
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
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DanielWalton
Frequent Contributor
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
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