Specify Transformations Map Uses?

[RyanCoodey]

Is there any way to set the transformation the Map uses?

All our data is in either NAD83 or NAD27... and we use ESRIs services that are WGS84.  The NAD83 data projects nicely to WGS84 with the default transformation, but NAD27 to WGS84 does not...  so how can I change/specify the transformation being used with ArcGIS server and the WPF app?

Thanks a lot!

[dotMorten_esri]

This samples shows how to specify a map projection: http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#DefineMapProjection

However note that tiled layers that doesn't match the map's spatial reference will not render. So if you are not using WGS84 of WebMercator, you won't be able to use ArcGIS Online maps.

[RyanCoodey]

So there is no way then to just specify the transformation used from NAD_27 to WGS_84?

We would like to use ArcGIS Online maps (which as you said the map will have to be WGS_84 or they don't show up), but the NAD_27 data doesn't project nicely to this... we would like to use the NAD_1927_To_WGS_1984_79_CONUS transformation...

Thanks Morten!

[DaveTimmins]

You can't do it via the API but you can achieve this by specifying the transformation on the Data Frame in ArcMap and then publish that MXD for consumption in your app.

[RyanCoodey]

Ahh, ok, thank you much for that info... but it has to be serverd up as a MXD?  MSD doesn't retain this info im guessing?

Thanks again!

[DaveTimmins]

Not 100% but you can definitely publish it as an MSD. I guess the easiest thing would be to try it out.

Some more info on MSD publishing is available here

http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=Publishing_optimized_map_services

http://webhelp.esri.com/arcgisserver/9.3.1/java/index.htm#supp_func_msd_based_svcs.htm

[RyanCoodey]

AWESOME, it works with a MSD... I should have know this, hence the warning when serving them up if they are in different coord systems.  This takes care of most my problem, but one more question...  How can I do this with an Image Service in ArcGIS Server (we don't use the stand alone image server, just the AGS extension)?

Thank you much!