Datum transformation parameters in prj file?

Question

Hi, I have written a standalone application that will export Shape files but I need some help with the prj files. How can I write custom geodesy to the prj so that my shape files will load in ArcMAP whitout triggering this annoying "Geographic Coordinate Systems Warning" dialogue box? My current prj file looks like this (on one single line of course): PROJCS["MyED50NUTM31N", GEOGCS["MyED50N", DATUM["", SPHEROID["",6378388.0,297.0], TOWGS84[-116.641, -56.931, -110.559, 0.893, 0.921, -0.917, -3.52]], PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]], PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0], PARAMETER["False_Northing",0.0], PARAMETER["Central_Meridian",3.0], PARAMETER["Scale_Factor",0.9996], PARAMETER["Latitude_Of_Origin",0.0], UNIT["Meter",1.0]] Does ArcMAP read the TOWGS84 parameter? (As listed here http://docs.geotools.org/stable/javadocs/org/opengis/referencing/doc-files/WKT.html) When I manually define a custom datum transformation in ArcMAP, the "CreateCustomGeoTransformation" tool will show this syntax: GEOGTRAN(METHOD('Position_Vector'],PARAMETER['X_Axis_Translation',-116.641],PARAMETER......... Can I use this syntax in my WKT (=prj) file instead of the TOWGS84 parameter? I don't want to adopt the ESRI or EPSG naming / numbering scheme. I want full flexibility for custom definitions - it should work even it's not already defined by ESRI or EPSG. Is this possible? PS: I know that particular shift is already predefined in ArcMAP - I'm just using it as an example. BR, Leifster

RobertBorchert · Answer

Your over thinking it. Simply make your MXD into the projection you want to use. When you create a new mxd it should automatically assign the projection to the projection of the first file you add it if has a projection. Hi, I have written a standalone application that will export Shape files but I need some help with the prj files. How can I write custom geodesy to the prj so that my shape files will load in ArcMAP whitout triggering this annoying "Geographic Coordinate Systems Warning" dialogue box? My current prj file looks like this (on one single line of course): PROJCS["MyED50NUTM31N", GEOGCS["MyED50N", DATUM["", SPHEROID["",6378388.0,297.0], TOWGS84[-116.641, -56.931, -110.559, 0.893, 0.921, -0.917, -3.52]], PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]], PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0], PARAMETER["False_Northing",0.0], PARAMETER["Central_Meridian",3.0], PARAMETER["Scale_Factor",0.9996], PARAMETER["Latitude_Of_Origin",0.0], UNIT["Meter",1.0]] Does ArcMAP read the TOWGS84 parameter? (As listed here http://docs.geotools.org/stable/javadocs/org/opengis/referencing/doc-files/WKT.html) When I manually define a custom datum transformation in ArcMAP, the "CreateCustomGeoTransformation" tool will show this syntax: GEOGTRAN(METHOD('Position_Vector'],PARAMETER['X_Axis_Translation',-116.641],PARAMETER......... Can I use this syntax in my WKT (=prj) file instead of the TOWGS84 parameter? I don't want to adopt the ESRI or EPSG naming / numbering scheme. I want full flexibility for custom definitions - it should work even it's not already defined by ESRI or EPSG. Is this possible? PS: I know that particular shift is already predefined in ArcMAP - I'm just using it as an example. BR, Leifster

MelitaKennedy · Answer

Hi Leifster,

No, we don't support the TOWGS84 parameter nor do we support including a transformation WKT in the prj file/spatial reference information. We're 'late-binding', not 'early-binding'. You only pick a transformation when you need it.

Using the Create Custom Geographic Transformation tool, the definition is persisted for you so you can then use the same transformation in the Project tools, for instance.

Another possibility is the projection engine environment variable, PEOBJEDITHOME, where you can define a coordinate system or transformation, including giving it a WKID. The definitions would have to be set up before starting ArcGIS, and if you do need to define a custom spheroid, it gets a little complicated (you have to define the geogcs, datum, and spheroid separately). If you're interested, send me an email, mkennedy at esri dot com.

Melita