[GRASS5] Severe internal bugs in raster format

Markus Neteler neteler at geog.uni-hannover.de
Thu Nov 18 12:43:20 EST 1999

Dear developers,

sorry for bad news: but it seems there is a lot
of confusion in raster format read/write in several

 d.rast a_raster_map
 d.rast.zoom # we want to look at some pixels only
 d.rast.num  # show cell values
 d.what.rast # query with mouse: result is different
 r.out.ascii # result is different as well

(from A. Lobo:)
r.stats: some inconsistent results comparing to r.average
 *First, I compute the per-class averages:
     r.average base=medv cover=test out=borra.me
 *Second, I check the result for, i.e., class 23:
     d.what.rast map=medv,borra.me
     2676500(E) 4409500(N)
           medv in user1  (23)S_SUPRAMEDITERRANEAN_ZONE
           borra.me in user1, quant   (111)
           borra.me in user1, actual  (110.794075)
 *Third, I compute the statistics for each class, but the results are not
  the same as given by d.what.rast. For example, for class 23:
     r.stats -c in=medv,borra.me
     r.stats:  100%
       23 110.299171-110.744906 6082
 *While d.what.rast was giving 110.794075.

We should check this quickly, otherwise we cannot trust any result.
I guess the problem is due to ".5" (half raster cell) addition
for query any some potential mixture of 
  - save values at cell center
  - save values at cell corner (which is wrong as far as I know but correct
                                for ESRI).

Another bug: r.in.arc reads in ARC/INFO grid files reversed.
ESRI saves from lower left to upper right, GRASS from
upper left to lower right. The module does not (yet) take
care of this. I would be able to fix in GRASS 4.x but in GRASS 5
the row number cannot be specified any more (G_put_raster_c_row()).
So we have to flip the input file or something else... How to do this?

Your help is appreciated!
Hope to have better news soon,


If you want to unsubscribe from GRASS Development
Team internal mailing list write to:
minordomo at geog.uni-hannover.de with
subject 'unsubscribe grass5'
length: 2257
max: 0

More information about the grass-dev mailing list