[GRASS-user] r.water.outlet and longitude / window issue

[Andy Wickert]

Hi GRASS user-list,

I think that I have run into a bug in either the computational window
definition or the r.water.outlet program (or maybe something else) that has
to do with defining degrees West as either positive (East-longitude >180) or
negative.

What happens is that, for example, I type:
r.water.outlet drainage=$watershed_direction basin=temp_basin easting=196
northing=60 --verbose --overwrite

And GRASS returns:
WARNING: Warning, ignoring point outside window:
         -164.0000,60.0000

This occurs no matter whether I specify the longitude as a positive
East-longitude (as above), as a negative value (e.g.,-164), or as, e.g.,
164W. (196E is not allowed).

The problem is not my window definition, which includes the point in
question:
proj:       3
zone:       0
north:      73:00:30N
south:      49:59:30N
east:       144:59:30W
west:       162:59:30E
cols:       3121
rows:       1381
e-w resol:  0:01
n-s resol:  0:01
top:        1
bottom:     0
cols3:      3121
rows3:      1381
depths:     1
e-w resol3: 0:01
n-s resol3: 0:01
t-b resol:  1

When I use r.what, it gives me East-longitudes (values >180) for regions to
the East of the 180 meridian. But r.water.outlet insists on switching
everything to negatives no matter what input I give it, which I think is a
source of the problem.

The strangest thing about this is that I ran into this problem while
following a routine that I had written several months ago in Bash; last
time, I ran r.water.outlet on North America (all in degrees-west land) with
no problems at all. I just checked the computational region (window) files
for that run, and they look very similar to the ones I am using now. I have
no clue why I didn't run into this problem back then / why it is cropping up
now; both computers are running GRASS 6.4.1 on Ubuntu Linux.

Anyway, if anyone has any suggestions, I'm all ears. Many thanks in advance,

Andy Wickert
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