I am working on a project in which i need to calculate the points form on CRS to another, but as we the source and target CRS are only determine on runtime.
ISpatialReference source = GCS_North_American_1983
ISpatialReference target = UTM Zone 13 North (108 W - 102 W Longitude)
IEnvelope extent = rasterLayer.VisibleExtent;
Console.WriteLine(extent.XMax); == -97.815540361118
Console.WriteLine(extent.XMin); == -102.045540576002
Console.WriteLine(extent.YMax); == 39.933228902485
Console.WriteLine(extent.YMin); == 37.113228759229
IGeoTransformation geoTransformation = "NAD_1927_To_NAD_1983_NADCON"
geoTransformationOperationSet.Set(esriTransformDirection.esriTransformForward, geoTransformation);
geoTransformationOperationSet.Set(esriTransformDirection.esriTransformReverse, geoTransformation);
//So we need to go in reverse order. as source is in NAD83 and Target is in NAD27. and returns correct results matched with ArcMap but going forward results wrong output.
geometry.ProjectEx(target, esriTransformDirection.esriTransformReverse, geoTransformation, false, 0.0, 0.0);
Console.WriteLine(extent.XMax); == 1138797.89197912
Console.WriteLine(extent.XMin); == 752503.366222885
Console.WriteLine(extent.YMax); == 4444925.18943959
Console.WriteLine(extent.YMin); == 4111314.85519851
if we do the forward transformation return incorrect result.
1138738.17611084
752424.161510695
4444923.04572637
4111317.16066915
So how can I determine which direction we need to use? Like forward/reverse. Is there any way we can find out using arcobject API return use fwd or reverse. I looked into the IGeoTransformation but no success, there are many different predefined GeoTransformation which can use in both fwd or reverse if supported.
Thanks.
