[GRASS-user] combining tiles

Hamish hamish_nospam at yahoo.com
Tue Feb 6 17:38:27 EST 2007

Gerald Nelson wrote:
> > Why not use r.patch in grass to combine them,

Tyler Smith wrote:
> Yes, r.patch is the function I need, as several people have pointed
> out off-list. I read the man page for r.patch before but didn't
> understand it. I didn't realize that the tiles I imported were
> automatically filled out with -9999 values such that they actually
> covered the whole region, and not just that portion of the region that
> they have data for. Now that I understand this, r.patch is obviously
> what I need, and what I was in fact duplicating with my complicated
> GRASS-Emacs-R-Emacs-GRASS translation.

tips o'the day:

This command will turn -9999s into NULLs:
  r.null setnull=-9999

This command will zoom to the extent of non-NULL data in a map:
  g.region zoom=map

This command will extend the region to cover both raster maps:
  g.region rast=map1,map2


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