Using the "C API" and modifying the projection...

[Frank Warmerdam]

Ian Erickson wrote:
> Nope.
> 
> So I'm trying to distill this down...  There's a bunch going on here so 
> I thought I should focus on just the one element that's cauing the 
> problem - that being msLoadProjectionString().  So with a simple map 
> with a projection specifed as epsg:4326, I figured I'd try to alter the 
> projection and then save the output map....
> 
> Guess what, the projection remains unchanged....  So there appears to be 
> a step (or 5) that I'm missing here...
> 
> //-------------------------------------------------------------------
> 
>    mapObj *map = NULL;
>    imageObj *image = NULL;
> 
>    msSetup();
>    map = msLoadMap( "C:\\original.map", NULL );
>    if (!map) {
>        cout << "There is an error loading the map..." << endl;
>        return;
>    }
>    //Trying to change the projection to epsg:4269 (and then verify it in 
> the output.map file)...
>    msLoadProjectionString( &(map->projection), "+init=epsg:4269" );
>    msSaveMap( map, "C:\\output.map" );
>      image = msDrawMap( map );
>    msSaveImage( map, image, "C:\\output.png" );
> 
>    msFreeImage( image );
>    msFreeMap( map );
>    msCleanup();
>    cout << "Complete." << endl;

Ian,

I have reviewed the msLoadProjectionString() code, and I can't really see
how the above could fail to alter the map projection declaration unless
it was originally the same as what you are setting it to or if USE_PROJ
is not defined in the build in which case the original projection
should also not be defined.

What does "mapserv -v" look like?  What does the MAP portion of the original
and saved map file look like?

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org