[GRASS5] r.in.png error?

Glynn Clements glynn.clements at virgin.net
Wed Sep 1 20:24:45 EDT 2004

David Piasecki wrote:

> I used the PNG driver in GRASS to create a PNG image from my data. I 
> verified that the PNG image exists, and I can view it with any app 
> capable of reading the PNG format. I have not modified the region, and 
> I have verified that it is the same as when I originally created the 
> PNG file. However, when I attempt to import the PNG file using 
> r.in.png, I get the following error...
> 640 x 480 image, 8 bits palette+transparency // this is just extra 
> since I had the verbose option on
> WARNING: G_set_window(): Illegal latitude for North
> ERROR: Unable to set window
> Is there a way around this error?

This is a known issue with importing rasters into a lat/lon location. 

Unless the raster has georeferencing information (and the importer can
use it; AFAIK, this is currently only true of r.in.tiff and
r.in.gdal), rasters are imported with the bottom-left corner at (0,0)
and the top-right corner at (W,H), where W and H are the width and
height of the raster.

In this case, r.in.png is trying to set the top-right corner of the
region to (640,480), which isn't valid for a lat/lon location.

A workaround is to change the location's projection to X/Y with
g.setproj, import the raster, set its boundaries with r.region, then
change the location back to lat/lon.

Ultimately, someone needs to change the various r.in.* programs to
handle this situation.

Glynn Clements <glynn.clements at virgin.net>

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