[GRASS-user] r.proj: Regions Do Not Match -- [RESOLVED]

[Rich Shepard]

On Wed, 2 Mar 2011, Hamish wrote:

>>   The DEMs were originally in lat/lon (NAD83) and imported to that
>> location.
>
> if the originals are lat/lon then they need to be imported to a lat/lon
> location,

   As stated.

> ok, that looks good, although I wonder why the east and west have become
> negative.

   Let's deal with that later. I see a problem with the region on my lon/lat
location:

GRASS 6.5.svn (Nevada-ll):~/grassdata > g.region -p
projection: 3 (Latitude-Longitude)
zone:       0
datum:      nad83
ellipsoid:  grs80
north:      1N
south:      0
west:       0
east:       1E
nsres:      1
ewres:      1
rows:       1
cols:       1
cells:      1

   So, I do this:

GRASS 6.5.svn (Nevada-ll):~/grassdata > g.list rast
----------------------------------------------
raster files available in mapset <PERMANENT>:
dem_area15 dem_area2  dem_area3  dem_area8  dem_area9

Then set the region to dem_area2 (as a first step). This yields:

GRASS 6.5.svn (Nevada-ll):~/grassdata > g.region -p
projection: 3 (Latitude-Longitude)
zone:       0
datum:      nad83
ellipsoid:  grs80
north:      42N
south:      41N
west:       116W
east:       115W
nsres:      0:00:01
ewres:      0:00:01
rows:       3600
cols:       3600
cells:      12960000

   Ah-h-h! That's better.

And now when I run r.proj it works. Why the AEA location has negative east
and west values I cannot explain.

   Conclusion: I did not set the region in the long/lat location based on an
existing map so it had random and meaningless numbers.