[GRASS5] r.in.png error?

Glynn Clements glynn.clements at virgin.net
Thu Sep 2 23:45:40 EDT 2004

Namnath, Sharyn wrote:

> I've been trying to look up how to use g.setproj, but I haven't figured it
> out yet.  I am currently using Grass in php. I have created the PNG files,
> and now want to access a chosen area PNG file so I can allow the user to
> zoom in closer or pan the image. How does one use g.setproj to change the
> location's projection to X/Y?  I tried it in the Grass terminal and it
> appears to be interactive.

Right. There isn't a non-interactive version; you would have to modify
the WIND file directly. Essentially, you need to change the value on
the "proj:" line; X/Y is 0, lat/lon is 3.

However, it's debatable whether you should be re-importing images
which were created using the PNG driver into GRASS. For
zooming/panning around a map (or series of maps), you would normally
create a new PNG file each time, by the same means that the original
PNG file was created.

In most cases, rendering a map to an image will lose information. If
you re-import the rendered image as a map, then render a new image
from that map, the errors will accumulate.

Glynn Clements <glynn.clements at virgin.net>

More information about the grass-dev mailing list