EsriReprojector "Geographic Transformation" Parameter

Hi,

 

 

I guess that would be a question for ESRI support, as the EsriReprojector uses the ArcGIS libraries for the actual reprojection. But I suspect the answer will be that it depends completely on your source and destination coordinate system.

 

 

Unless you specify the "Geographic transformation" type, you risk that a given transformation does stuff that might introduce inaccuracies, such as passing through WGS84 LatLong between the source and destinatino coordinate system, or that it prioritizes speed rather than accuracy when choosing a transformation algorithm. By setting the transformation type you will have full control on what's happening.

 

 

Btw, the FME CsMapReprojector has a similar option called "Transformation". I suspect you can substitute "FME" with "ArcGIS" in the description of how it works: If set to <Auto> or left blank, FME will attempt to choose an appropriate transformation.

 

 

David

Thanks David

 

 

This is from the ESRI Project Tool's Geographic Transformation parameter:

 

Geographic Transformation (optional)

 

This method can be used for converting data between two geographic coordinate systems or datums. This optional parameter may be required if the input and output coordinate systems have different datum.

 

So if the EsriReprojector is dependent on the ESRI tool this implies it's a required parameter when going between datums eventhough it will technically still let you run it without it being populated.

I find that all of my projecting works better if I just use the REPROJECTOR transformer and stay away from the EsriReprojector.

Hi,

 

 

the ESRI help text does say the parameter is optional, but I guess it will either use an opproximation or an intermediary transformation if it isn't specified when "needed".

 

 

Regarding the Reprojector, I'd recommend you rather use the CsMapReprojector, as per the recommendations from Safe.

 

 

David

Thanks guys, I'll def check out the CsMapReprojector!