Details Ticket 3910


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Serial Number 3910
Subject v.buffer - creating buffer areas does not work
Area grass6
Queue grass
Requestors wolfgang.qual@gmx.net
Owner none
Status resolved
Last User Contact Wed Aug 16 17:40:29 2006 (2 yr ago)
Current Priority 70
Final Priority 70
Due No date assigned
Last Action Wed Aug 16 17:40:29 2006 (2 yr ago)
Created Wed Dec 21 12:52:35 2005 (3 yr ago)

Transaction History Ticket 3910


Wed, Dec 21 2005 12:52:35    Request created by guest  
Subject: v.buffer - creating buffer areas does not work

Platform: GNU/Linux/i386
grass obtained from: CVS
grass binary for platform: Downloaded precompiled Binaries
GRASS Version: 6.1.cvs

Hi,
I tried to create a new area boundary around a line theme (where the lines describe
a closed ring). Thought it would be easy to do it like this:

v.buffer in=ausschnitt out=buff_ausschnitt bufcol=gesamtbr type=boundary

But GRASS won't create a new theme (there is result theme "buff_ausschnitt",
but it is not possible to open it: QGIS "The layer is no valid layer and cannot
be added to the map"). 
After that, I tried to first create a line buffer theme (works fine) and then
convert it to a area boundary theme using v.type. However, the new area boundary
theme does not have the shape of the line buffer theme. The new created polygon
fills out the space inside the ring.

Regards,
Wolfgang
Thu, Dec 22 2005 02:45:11    Mail sent by hamish_nospam@yahoo.com  
Return-Path <hamish_nospam@yahoo.com>
Delivered-To grass-bugs@lists.intevation.de
Date Thu, 22 Dec 2005 14:44:56 +1300
From Hamish <hamish_nospam@yahoo.com>
To Request Tracker <grass-bugs@intevation.de>
Cc grass5@grass.itc.it
Subject Re: [GRASS5] [bug #3910] (grass) v.buffer - creating buffer areas does not work
Message-Id <20051222144456.75154772.hamish_nospam@yahoo.com>
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> this bug's URL: http://intevation.de/rt/webrt?serial_num=3910
> ---------------------------------------------------------------------
> 
> Subject: v.buffer - creating buffer areas does not work
..
> GRASS Version: 6.1.cvs
..
> I tried to create a new area boundary around a line theme (where the
> lines describe a closed ring). Thought it would be easy to do it like
> this:
> 
> v.buffer in=ausschnitt out=buff_ausschnitt bufcol=gesamtbr
> type=boundary
> 
> But GRASS won't create a new theme (there is result theme
> "buff_ausschnitt", but it is not possible to open it: QGIS "The layer
> is no valid layer and cannot be added to the map").

If there are no boundary features in the input map, the buffering around
boundaries will be empty. Use v.type to convert.

Remember that lines will be buffered both sides, areas (boundaries) only
outside themseleves.


> After that, I tried to first create a line buffer theme (works fine)
> and then convert it to a area boundary theme using v.type. However,
> the new area boundary theme does not have the shape of the line buffer
> theme. The new created polygon fills out the space inside the ring.

d.vect cat=1-999999

will draw only real features (not fill holes).


I think you need to run v.type before v.buffer.



Hamish


Thu, Dec 22 2005 02:58:02    Comments added by hbowman  
> bufcol=

I don't guarantee that option is free of bugs yet. Actually I can 
guarantee it has bugs, and is currently only ok for points. 
Need to add a temporary warning I guess. Search for the thread on 
the devel list for more info. 

Currently a combo of multiple 'v.extract where=' + v.buffer, then
v.overlay will probably do to get your job done.


Hamish
Wed, Aug 2 2006 22:00:09    Mail sent by msieczka  
Wolfgang,

Could you try to reproduce your bug with current CVS? Or send me (tutey at
o2.pl) the problematic data in a shapefile or whatever, with information how
to proceed so I can try it myself? I'm asking this because I realy can't
reproduce this error with my data, maybe I'm missing something.

Any feedback will be appreciated.

Best,
Maciek
Wed, Aug 16 2006 17:40:29    Status changed to resolved by msieczka  
Wed, Aug 16 2006 17:40:29    Mail sent by msieczka  
When you decide to check this bug and it shows it is still there please reply
to this email CCing me tutey at o2.pl.

For now I'm closing it as "can't reproduce".

Maciek
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