Function: rasgeo

Syntax

rasgeo (<file>)

Type

numeric

Returns

Geographic information from a geo-referenced image file. Six values are returned:

(1,2,3) the world co-ordinates of the top-left pixel of the image in some projection,

(4,5) the x,y scale factors, i.e. what 1 pixel represents in world units,

(6) the rotation of the image measured in the current angle units.

The image file must contain geo-referencing information otherwise 6 zeros are returned and the function error flag funcerr will be set to -1.

Parameters

• <file>
  The file name. If it does not exist, 6 zero values are returned.

Notes

Currently the only image files supported for this function are TIFF files (with associated .TFW information files) and ECW files.

Example

numeric vals[6] = rasgeo('myfile.tif')
unless (funcerr) {
   point pt = <vals[1],vals[2],vals[3]>;# We could also have used myfile.tfw
   numeric factors[] = vals[4:5]
   numeric angle = vals[6]
   tell <'Point:',pt,'Scales:',factors,'Angle:'angle>
}

See Also