[GRASS-dev] Re: [GRASS GIS] #789: g.region option to expand the
computational region of about "some" pixels?
GRASS GIS
trac at osgeo.org
Thu Oct 15 04:18:21 EDT 2009
#789: g.region option to expand the computational region of about "some" pixels?
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Reporter: nikos | Owner: grass-dev at lists.osgeo.org
Type: enhancement | Status: new
Priority: normal | Milestone: 7.0.0
Component: default | Version: unspecified
Resolution: | Keywords: g.region, expand computational region
Platform: Unspecified | Cpu: Unspecified
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Comment (by nikos):
Replying to [comment:1 hamish]:
> did you try the g.region align=rastermap option?
>
> fwiw, -a grows outwards.
>
> > Matching the region over a point map is the problem! The
> > points at the borders (happens quite often to me when the
> > resolution of the raster map is low and so does the
> > resolution of the region successively) are not taken
> > into account.
>
> could you explain that more? I don't understand it.
a. Imagine a point-grid (i.e. points or centroids that would form a square
if connected)[[BR]]
b. match the region over this point-grid (g.region -a vect=point-grid #
the points at the edges are just to be seen when drawing the vector point-
grid with d.vect for example).[[BR]]
c. The points at the edges are ignored by v.what.rast vector=point-grid
rast=LowResRaster
>
> can you provide an example using Spearfish's bugsites + elevation.dem or
something from the NC standard dataset?
Right. I'll try to re-produce this in Spearfish.
> fwiw the region growing I've done has always been for cosmetic reasons.
in those cases usually make the res=res*2 (or 10) with the -a flag, then
run g.region again with the original region value.
Would this (res=res*X) affect v.what.rast?[[BR]]
(Please, wait till I provide a Spearfish example. No reason to comment
more on this. Also, the "trick" is an optimal solution I think. Have to
try this out.)
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Ticket URL: <http://trac.osgeo.org/grass/ticket/789#comment:3>
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