It is obviously giving me two different locations when running it with and without.
I need help explaining exactly happens when it is not populated to encourage that it is consistently populated in the future.
EsriReprojector "Geographic Transformation" Parameter
How does the EsriReprojector handle reprojection between two datums if the "Geographic Transformation" parameter is not populated?
Userlevel 4
- 8177 replies
-
2 December 2014
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.
Userlevel 4
- 8177 replies
-
3 December 2014
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!
Reply
Enter your username or e-mail address. We'll send you an e-mail with instructions to reset your password.