[GRASS-user] v.to.rast in grass70

Mon Apr 16 03:58:30 EDT 2012

Thanks for quick response and sorry for delayed response from my side.
This is the second time , I have noticed that v.to.rast changes the region
settings equal to display resolution in GRASS70.
As, it cannot be reproduced at test side.
I will send more data the next time.
At present, I have created another mapset for working on v.to.rast and my
base rasters and vectors are kept securely in "PERMANENT" mapset. I haven't
faced the problem since.
Thanks again.

On Tue, Apr 10, 2012 at 9:30 PM, <grass-user-request at lists.osgeo.org> wrote:

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>   1. Re: r.stream.extract Syntax Problem (Markus Metz)
>   2. Re: v.to.rast in grass70 (Markus Metz)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 10 Apr 2012 09:14:55 +0200
> From: Markus Metz <markus.metz.giswork at googlemail.com>
> Subject: Re: [GRASS-user] r.stream.extract Syntax Problem
> To: Rich Shepard <rshepard at appl-ecosys.com>
> Cc: grass-users at lists.osgeo.org
> Message-ID:
>        <CAG+h=FFXNBRd8E_K88NeQPDGZXLDa71sxyDLJzez+a=tyGjR8g at mail.gmail.com
> >
> Content-Type: text/plain; charset=ISO-8859-1
>
> [Answering to your latest post in a new thread, but I prefer to keep
> it all in one thread.]
>
>
> On Tue, Apr 10, 2012 at 1:54 AM, Rich Shepard <rshepard at appl-ecosys.com>
> wrote:
> > On Mon, 9 Apr 2012, Markus Metz wrote:
> >
> >> The computational region should be aligned to the DEM in order to get
> >> accurate results. Aligning to the resolution of the DEM is not enough,
> >> i.e. you should use g.region align=DEM instead of g.region res=XXX -a.
> >> r.stream.extract should work if only a subregion is to be analysed by
> >> setting the computational region accordingly and/or creating a MASK e.g.
> >> for a specific basin.
> >
> >
> > Markus, madi, et al.:
> >
> >  The region does need to be set with a mask (in my case, and based on the
> > v.to.rast output of the individual subbasins).
>
> v.to.rast? Basins as created by r.watershed, r.stream.basins and
> r.water.outlet are already raster maps.
> >
> >  The last advice in the example on the manual page is to compare the
> > weighted and unweighted extracted stream maps and "see which looks
> better."
> > As a newcomer to this module I have no experience on what "better" looks
> > like.
> >
> >  Attached are two .pdf files. One shows the weighted output streams, the
> > other the unweighted output streams. Both have the vector streams
> overlaid
> > on them. The weighted output has a solid yellow background and I don't
> know
> > what that represents.
>
> In this case there is indeed no answer to "what looks better" because
> both look terrible, to be honest. Something terrible must have
> happened to the DEM, or there are indeed completely flat areas in the
> west. If the aim is to extract streams that resemble the digitized
> vector lines, the DEM you used seems to be not suitable. You could try
> to run r.stream.extract with the DEM as the only input and a larger
> threshold. The region should be aligned to the DEM first with g.region
> -p align=dem. If that produces reasonable results, you can try to
> fine-tune by adjusting the threshold and supplying a (weighed)
> accumulation map as additional input.
>
> Markus M
>
> PS: Please do not change the thread all the time. With regard to this
> subject, you have started now the 7th or so thread, I lost count,
> impossible for anyone to follow.
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 10 Apr 2012 10:01:11 +0200
> From: Markus Metz <markus.metz.giswork at googlemail.com>
> Subject: Re: [GRASS-user] v.to.rast in grass70
> To: Paulo van Breugel <p.vanbreugel at gmail.com>
> Cc: grass-user at lists.osgeo.org
> Message-ID:
>        <CAG+h=FFKW0U9XPbw+4L93K1gci2tMbU8o-B4umSXudUAUc18Uw at mail.gmail.com
> >
> Content-Type: text/plain; charset=ISO-8859-1
>
> On Mon, Apr 9, 2012 at 12:08 PM, Paulo van Breugel
> <p.vanbreugel at gmail.com> wrote:
> > I can confirm there are issues in how GRASS 7 handles region settings.
> In my
> > case, when using v.to.rast, the region settings are reset to the default,
> > i.e., the raster is converted using the default region settings rather
> then
> > the current. I am now at revision 51177. In a previous revision (51117)
> I
> > had a problem with region settings when using r.patch, see Ticket #1636
> > (http://trac.osgeo.org/grass/ticket/1636). These issues seem to be
> > independend of the mapset (it happens in both PERMANENT and other
> mapsets).
> >
>
> I can not reproduce this problem. I tested in the North Carolina
> dataset, mapset user1.
>
> I displayed boundary_county, zoomed to the default region. Then I
> zoomed to a small part of the boundary_county vector and set the
> region from display. Then I zoomed to a different part of the vector
> that does not overlap with the current region. Thus the current
> region, the default region, and the display extents were all different
> from each other. Then I ran v.to.rast on the boundary_county vector.
> v.to.rast correctly used the current region and nothing was changed
> after v.to.rast was completed. This is r51306.
>
> Markus M
>
> > Paulo
> >
> >
> >
> >
> > On 04/09/2012 08:44 AM, Pankaj Kr Sharma wrote:
> >
> > Dear Grass users and developers,
> >
> > I just noticed that in grass70 , the v.to.rast module changes
> computational
> > region / current region
> > resolution to the display extent and resolution after finishing.
> >
> > My maps are in "PERMANENT" mapset. And, I have tried a number of options
> ,
> > but cannot reset the resolution of raster thus created to the required
> > resolution.
> >
> > Thanks.
> >
> >
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