Transformation method during re-project?

[mcoop]

Hello,

Is it possible to choose which transformation method/parameters are being used during re-project? Can this be included in the WKT somehow?

I need to go from NAD27 to NAD83 but the default transformation that is used is not the correct method.

Thanks!

[rparker]

Yes. You can create your own custom WKT or you can import one from another location (such as a .prj file).

Please paste in the source WKT you would like to modify and please let me know the transformation you would like to use.

[mcoop]

The source WKT is this:

PROJCS["NAD_1927_UTM_Zone_13N",
GEOGCS["GCS_North_American_1927",
DATUM["North_American_Datum_1927",
SPHEROID["Clarke_1866",6378206.4,294.9786982]],
PRIMEM["Greenwich",0],
UNIT["Degree",0.017453292519943295]],
PROJECTION["Transverse_Mercator"],
PARAMETER["False_Easting",500000],
PARAMETER["False_Northing",0],
PARAMETER["Central_Meridian",-105],
PARAMETER["Scale_Factor",0.9996],
PARAMETER["Latitude_Of_Origin",0],
UNIT["Meter",1]]

I would like to re-project to this:

PROJCS["NAD_1983_UTM_Zone_13N",
GEOGCS["GCS_North_American_1983",
DATUM["North_American_Datum_1983",
SPHEROID["GRS_1980",6378137,298.257222101]],
PRIMEM["Greenwich",0],
UNIT["Degree",0.017453292519943295]],
PROJECTION["Transverse_Mercator"],
PARAMETER["False_Easting",500000],
PARAMETER["False_Northing",0],
PARAMETER["Central_Meridian",-105],
PARAMETER["Scale_Factor",0.9996],
PARAMETER["Latitude_Of_Origin",0],
UNIT["Meter",1]]


I used ESRI projection files to create these WKTs within GeoExpress 7. The transformation I would like to use is NAD_1927_to_NAD_1983_6 (this may be a specific code that only ESRI uses...) the method I think is "NTv2 - dataset=canada/QUE27-83". Basically any other method but NADCON aligns the image correctly.

Is that enough information for you to go on? Thanks for the help.

[rparker]

After some investigation I discovered that changing the transformation method is not presently available but we are now looking to add it to a future release.

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