[mapserver-users] getting coordinates from pixel
CATHIGNOL, Frederic
Frederic.CATHIGNOL at astrium-space.com
Mon Nov 26 23:21:42 PST 2001
Hello;
If I understand your problem, there is a function in the example gmap75 :
/************************************************************************/
/*function GMapPix2Geo($nPixPos, $dfPixMin, $dfPixMax, $dfGeoMin,
dfGeoMax,*/
/* $nInversePix) */
/* */
/* Utility function to convert a pixel position to geocoded */
/* position. */
/* */
/* The parameter $nInversePix could be set to 1 for Y pixel */
/* coordinates where the UL > LR. Else set to 0. */
/************************************************************************/
function GMapPix2Geo($nPixPos, $dfPixMin, $dfPixMax, $dfGeoMin, $dfGeoMax,
$nInversePix)
{
// $nPixPos : pixel position (X or Y)
// $dfPixMin, $dfPixMax : Pixel minimum and maximum (X or Y) of your map
on the screen (should be 0 to xxx)
// $dfGeoMin, $dfGeoMax : Geographic coordinate min max (X or Y) of your
map on the screen
$dfWidthGeo = $dfGeoMax - $dfGeoMin;
$dfWidthPix = $dfPixMax - $dfPixMin;
$dfPixToGeo = $dfWidthGeo / $dfWidthPix;
if (!$nInversePix)
$dfDeltaPix = $nPixPos - $dfPixMin;
else
$dfDeltaPix = $dfPixMax - $nPixPos;
$dfDeltaGeo = $dfDeltaPix * $dfPixToGeo;
$dfPosGeo = $dfGeoMin + $dfDeltaGeo;
return ($dfPosGeo);
}
Regards,
F.CATHIGNOL
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