Thanks for Answer: [Gdal-dev] How to custom my "Projected Coordinate Systems" inOGR

Frank Warmerdam warmerdam at
Thu Mar 15 21:20:44 EDT 2007

ÚO½¨Ã÷ wrote:
> Hi,Frank:
> Thanks for your reply.I will modify my code follow your advice.
> And i have another question:
> Is under the $GDAL_DATA$ directory have a file to describe which 
> projection hava how many parameter as well as their name,function. I 
> want give a common custome projection UI,if have the file i mention 
> above it can make me dynamicly control the Form style. If don't have 
> this file,should i control the UI according the projection various by 
> enumerate their parameter ?
> hope your next reply.


There is no file in $GDAL_DATA$ for this, but at the API
level we do have the following functions to fetch a list of
projection methods, and the corresponding parameter list.

I don't think I have been maintaining it very well, so there
may be a few omissions, but it is intended to make it possible
to build a GUI that "automatically" supports all the projection
methods of the current GDAL/OGR.

/* -------------------------------------------------------------------- */
/*      Projection transform dictionary query.                */
/* -------------------------------------------------------------------- */

char CPL_DLL ** OPTGetProjectionMethods();
char CPL_DLL ** OPTGetParameterList( const char * pszProjectionMethod,
                             char ** ppszUserName );
int CPL_DLL OPTGetParameterInfo( const char * pszProjectionMethod,
                                 const char * pszParameterName,
                                 char ** ppszUserName,
                                 char ** ppszType,
                                 double *pdfDefaultValue );

There appears to be some documentation on this page:

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at
light and sound - activate the windows |
and watch the world go round - Rush    | President OSGeo,

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