On 03/05/11 15:47, Micha Silver wrote:
On 05/03/2011 04:34 PM, Moritz Lennert wrote:
On 03/05/11 10:20, Micha Silver wrote:
On 05/03/2011 09:11 AM, Hanlie Pretorius wrote:
Hi Maris,
Thanks, your suggestion worked. With the region's resolution set to
5m, I got some output.
Hi Maris:
Sorry for butting in on this, but I don't understand why the region
resolution should make any difference to v.to.rast??
Would you mind to explain?
From the v.to.rast manual:
"v.to.rast will only affect data in areas lying inside the boundaries
of the current geographic region. Before running v.to.rast, the user
should therefore ensure that the current geographic region is
correctly set and that the region resolution is at the desired level."
Thanks, Moritz
What I'm trying to understand is the question about resolution. Would
you expect, as
Hanlie indicted, to get *no output* in the raster because of too course
resolution?
He claims that at 20m x 20m v.to.rast of a line feature created all NULL
cells, but at 5m x 5m the lines did appear in the raster.
??
Hanlie didn't tell us whether he applied Maris' first part of the
solution as well (but I guess he did):
g.region vect=contours_20m
I agree with you that resolution does not make the difference. However,
I guess that Maris meant that having a 20m resolution seems too coarse
for 20m contour lines, but even that is not clear as all depends on the
topography of the region in question. If you have 100m altitude change
for 50m horizontal change, then 20m is a bad choice of resolution, but
if you have 100m altitude change for 1km horizontal change, it should be
more than enough.
So, in conclusion, the region's resolution setting can make a huge
difference in v.to.rast, but in this particular case does not explain
why there was no output. This is certainly linked to the region's extension.
Moritz
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