[gdal-dev] What should I expect?

Martin Chapman chapmanm at pixia.com
Fri Aug 10 09:09:52 PDT 2012


Jorge,

It's a south up image.  If the gsd x value is negative the image is an
east to west image.  Normally a north up image will have a positive gsd x
and a negative gsd y.

Marty

-----Original Message-----
From: gdal-dev-bounces at lists.osgeo.org
[mailto:gdal-dev-bounces at lists.osgeo.org] On Behalf Of Jorge Arevalo
Sent: Friday, August 10, 2012 9:39 AM
To: gdal-dev at lists.osgeo.org
Subject: [gdal-dev] What should I expect?

Hello,

If while I'm executing gdalinfo against a raster layer I get a positive
value for pixel size Y, what of these scenarios is possible?

- The raster's map coordinate system sets the origin of the data in the
upper left corner.
- The raster is not georeferenced and its coordinates are interpreted as
image pixels, instead of map units.
- Any other situation (corrupt file?, other?)

I know this value is almost always negative. For example, in case of UTM
coordinate system. But, how common is to have a positive value for Y
coordinate?

Many thanks in advance

--
Jorge Arevalo
http://www.libregis.org
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