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Using arcobjects, I am trying to programmatically create a composite geotransformation and then use to project features with the geoprocessor. Found old VB6 code out there on the web, but I can't get it to work in C# .NET. When I try to use the projection tool in the geoprocessor, it fails and sends back a message saying "Invalid geographic transformation." The code I am using is below. Either I have built the composite transformation incorrectly, or, the geoprocessor cannot find it. Any ideas?


private void createAndUseCompositeGeoTrans()
        Geoprocessor gp = new Geoprocessor();
        gp.OverwriteOutput = true;
        object sev = 2;
        object dt = "";

            ISpatialReferenceFactory2 spatialReferenceFactory2 = new SpatialReferenceEnvironmentClass();
            ISpatialReference in_spatialReference1 = 

            ISpatialReference out_spatialReference2
               = spatialReferenceFactory2.CreateSpatialReference(esriSRProjCS2Type.esriSRProjCS_WGS1984SphereWebMercator.GetHashCode());
            ICompositeGeoTransformation compGeoTrs = (ICompositeGeoTransformation)new CompositeGeoTransformation();

            IGeoTransformation geoTransformation_A = spatialReferenceFactory2.CreateGeoTransformation((int)esriSRGeoTransformationType.esriSRGeoTransformation_NAD1983_To_WGS1984_1) as IGeoTransformation;
            compGeoTrs.Add(esriTransformDirection.esriTransformForward, geoTransformation_A);

            // WGS_1984_Major_Auxiliary_Sphere_To_WGS_1984
            IGeoTransformation geoTransformation_B = spatialReferenceFactory2.CreateGeoTransformation(108100) as IGeoTransformation;
            compGeoTrs.Add(esriTransformDirection.esriTransformReverse, geoTransformation_B);

            compGeoTrs.Name = "NAD1983_To_WGS_1984_Major_Auxiliary_Sphere";

            IMapGeographicTransformations mapGeotrans = (IMapGeographicTransformations)map;
            IGeoTransformationOperationSet geoTransOperationSet = mapGeotrans.GeographicTransformations;

            geoTransOperationSet.Set(esriTransformDirection.esriTransformForward, compGeoTrs);
            geoTransOperationSet.Set(esriTransformDirection.esriTransformReverse, compGeoTrs);
            ESRI.ArcGIS.Carto.IActiveView activeView = (ESRI.ArcGIS.Carto.IActiveView)map;

            ESRI.ArcGIS.DataManagementTools.Project projectTool = new ESRI.ArcGIS.DataManagementTools.Project();
            projectTool.in_dataset = "C:\\projects\\clients\\Freeport\\CAD_Tool\\sampledata\\Point.shp";
            projectTool.out_dataset = "C:\\projects\\clients\\Freeport\\CAD_Tool\\sampledata\\Test_002.shp"; ;
            projectTool.in_coor_system = spatialReferenceFactory2.CreateProjectedCoordinateSystem(in_spatialReference1.FactoryCode);
            projectTool.out_coor_system = spatialReferenceFactory2.CreateProjectedCoordinateSystem(out_spatialReference2.FactoryCode);
            projectTool.transform_method = "NAD1983_To_WGS_1984_Major_Auxiliary_Sphere";
            gp.Execute(projectTool, null);

        catch (System.Runtime.InteropServices.COMException CE)
            //throw CE;
            printMsg(rTxtBx_console, CE.Message + "\n\nLast GP Message:\n" + gp.GetMessages(ref sev), MsgTypes.err);
        catch (Exception E)
            printMsg(rTxtBx_console, E.Message + "\n\nLast GP Message:\n" + gp.GetMessages(ref sev), MsgTypes.err);

share|improve this question
Kirk, thank you for the reminder. I have been negligent. – rgwozdz Sep 19 '11 at 14:48
up vote 1 down vote accepted

Currently you do not have a valid composite geographic (datum) transformation. The input GCS is NAD 1983 HARN, not NAD 1983. You either need to change GT A to handle NAD 1983 HARN - WGS 1984 or change A to cover NAD83 - NAD83 HARN and make the current two transformations B and C.

If you go for the second case, many NAD 1983 - NAD 1983 HARN transformations are file-based so you'll need the pedata folder from ArcGIS desktop.

Lists of supported transformations for various versions are here.

share|improve this answer
If I create a CompositeGeotransformation is there some way to save it into the pe data folder so that it can be found if I use it's name in the Project gp tool? – Kirk Kuykendall Sep 19 '11 at 15:46
Thanks - you pointed out an important problem. In fact, I had the original input and output CS wrong - my sample shape file actually had an in CS of NAD1983SPCS_WASouthFT and my out CS should have been esriSRProjCS_WGS1984SphereWebMercator. I've edited the code above. However, I still have the "Invalid geographic transformation" error. It seems like the gp can't see the new composite geo transformation. – rgwozdz Sep 19 '11 at 16:10
@KirkKuykendall, unfortunately, no. The method would be as a gtf file, but they weren't designed to support the composite transformation. Projection engine doesn't support a composite transformation as a separate 'object' so there's no back-door available. – mkennedy Sep 19 '11 at 18:09
@rgwozdz, Do you have to use esriSRProjCS_WGS1984SphereWebMercator? This maps to 102113. If you're using 10, you could use 102100 aka 3857. This is based on WGS84, not WGS84 auxiliary sphere so you only need a single transformation. Another possibility to do the conversion in two processes. – mkennedy Sep 19 '11 at 18:11
@mkennedy, Unfortunately esriSRProjCS_WGS1984SphereWebMercator is required. Yes, I am working on doing the conversion in multiple project processes now. A pain, but at least there is a work around. Thanks very much. – rgwozdz Sep 19 '11 at 18:16

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