[Gdal-dev] OGR transforms

[Curt, WE7U]

On Thu, 14 Oct 2004, Curt, WE7U wrote:

> It appears to be this particular OCTTransform() that is causing the
> warnings spelled out earlier.  I'll try the latest release of GDAL
> to see if the warnings go away.
>
>
>   if (reverse_transformH) {
>     // Convert our view coordinates from WGS84 to this map
>     // layer's coordinates.
> //  if (!OCTTransform(reverse_transformH, 2, ViewX, ViewY, ViewZ)) {
>     if (!OCTTransform(reverse_transformH, 2, ViewX, ViewY, NULL)) {
>       fprintf(stderr,
>         "Couldn't convert points from WGS84 to map's spatial reference\n");
>     }
>     OCTDestroyCoordinateTransformation(reverse_transformH);
>     reverse_transformH = NULL;
>   }

Yep, that was the problem all right!  I needed to copy the original
WGS84 lat/long values into the ViewX/Y/Z arrays before doing the
transform each time.  Originally I had that code outside the layer
loop and so didn't have to worry about converting the same values
twice/three/XXX times.

So...   It's a never-mind sort of an issue.  ;-)

--
Curt, WE7U			         http://www.eskimo.com/~archer
"Lotto:    A tax on people who are bad at math." -- unknown
"Windows:  Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me:  I picked the coordinate system!"