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I have raster data (TIFF files) where I think it's spatial reference is in Gauß-Krüger ("DHDN_3_Degree_Gauss_Zone_3") and some shape files in UTM ("ETRS_1989_UTM_Zone_32N_8stellen"). As you can see in the screenshot the raster data (black drawings on top) has a slight offset to the UTM shape (light blue in background) of ~200 meters to north and ~90 meters east.

Screenshot

Example coordinates from one of the tfw files:

0.26051843980496
0.00000000000000
0.00000000000000 
-0.26051843980496 
3648545.83601748060000 
6038270.01816578210000 

I am wondering, what the reason is. I think of two possibleties for the raster:

  1. I suggested a wrong spatial reference. But how could I find the right one?
  2. The data itself is inaccurate. Then I need a way to define an offset for this raster. I tried adding the offset to the FalseEasting and FalseNorthing in IProjectedCoordinateSystem5, but it didn't help.

Does anyone have a clue?


Update/Solution

Thanks to Mintx I found the solution. The data itself is accurate but needs to be transformed to fit to the UTM project. Here is how I set the on the fly transformation on the map:

IMapGeographicTransformations transf = _map as IMapGeographicTransformations;
if (transf != null && transf.GeographicTransformations != null)
{
  ISpatialReferenceFactory2 srFactory = new SpatialReferenceEnvironmentClass();
  IGeoTransformation geoTransformation = (IGeoTransformation)srFactory.CreateGeoTransformation((int)esriSRGeoTransformationType.esriSRGeoTransformation_DHDN_To_ETRS_1989_8_NTv2);

  transf.GeographicTransformations.Set(esriTransformDirection.esriTransformForward, geoTransformation);
  transf.GeographicTransformations.Set(esriTransformDirection.esriTransformReverse, geoTransformation);    
}
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1 Answer

up vote 4 down vote accepted

Go to View->Data Frame Properties and switch your Coordinate System to DHDN_3_Degree_Gauss_Zone_3 and then click the Transformations... button to tell ArcMap how to get from the ETRS datum to DHDN.

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Try DHDN_To_ETRS_1989_8_NTv2 if it's available. Otherwise, you'll have to use the geographic_transformations.pdf file in the ArcGIS install's Documentation folder to check the areas of use for the various transformations. –  mkennedy Apr 17 '13 at 16:29
    
Thanks. I don't have ArcGis/ArcMap, only ArcEngine. Are the 'Data Frame Properties' the properties of the raster layer or of the .mxd project file? Or something else? –  gumo Apr 18 '13 at 10:45
    
Data frame is the properties of the .mxd –  Mintx Apr 18 '13 at 15:56
    
Thanks again, Mintx and mkennedy. I added the resulting code to the question. –  gumo Apr 19 '13 at 10:34
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