Details Ticket 858


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Serial Number 858
Subject v.support/v.build bug identified!
Area bug
Queue grass
Requestors neteler@itc.it
Owner none
Status resolved
Last User Contact Fri Mar 22 09:56:18 2002 (6 yr ago)
Current Priority 70
Final Priority 70
Due No date assigned
Last Action Fri Mar 22 09:56:21 2002 (6 yr ago)
Created Mon Nov 26 20:03:16 2001 (7 yr ago)

Transaction History Ticket 858


Mon, Nov 26 2001 20:03:16    Request created by guest  
Subject: v.support/v.build bug identified!

grass downloaded at: CVS Server, Germany

The v.support/v.build bug with causes the PNT_TO_AREA failed warnings
seems to be identified.

A micro-demo-location to reproduce the problem is available at
http://mpa.itc.it/markus/tmp/

The location contains to sample vector maps "good" and "bad",
each with two polygons only:

GRASS:~/grassdata/patdemo > l
total 12
drwxr-xr-x    2 neteler  ssi          4096 Nov 26 19:49 PERMANENT
drwxr-xr-x    2 neteler  ssi          4096 Nov 26 19:52 rawdata
drwxrwxrwx    7 neteler  ssi          4096 Nov 26 19:55 vector

In rawdata are the ARC-ASCII vector files and two import
scripts:

GRASS:~/grassdata/patdemo > ls -la rawdata
total 40
drwxr-xr-x    2 neteler  ssi          4096 Nov 26 19:52 .
drwxr-xr-x    5 neteler  ssi          4096 Nov 26 19:51 ..
-rw-r--r--    1 neteler  ssi            35 Nov 26 19:51 BadExample.dat
-rw-r--r--    1 neteler  ssi            67 Nov 26 19:51 BadExample.pnt
-rw-r--r--    1 neteler  ssi           273 Nov 26 19:51 BadExample.pol
-rw-r--r--    1 neteler  ssi            35 Nov 26 19:51 GoodExample.dat
-rw-r--r--    1 neteler  ssi            67 Nov 26 19:51 GoodExample.pnt
-rw-r--r--    1 neteler  ssi           273 Nov 26 19:51 GoodExample.pol
-rwxr-xr-x    1 neteler  ssi           154 Nov 26 19:52 import.BadExample.sh
-rwxr-xr-x    1 neteler  ssi           159 Nov 26 19:52 import.GoodExample.sh
Now the GRASS bug: v.support writes
PNT_TO_AREA failed: (1681015.000000, 5118635.000000) (Category 694020)
PNT_TO_AREA failed: (1680445.000000, 5118795.000000) (Category 54014)

when two or more polygons have the same starting point (the "bad" map). 
The identical "good" map with rotated nodes runs well.

That may be the key to understand all the E00 and SHAPE problems
which are regularly reported.

Thanks to Lorenzo Potrich (ITC-irst) for identifying this problem.

Please someone may fix this severe problem...

Markus Neteler
Mon, Nov 26 2001 20:05:05    Priority changed to 70 by mneteler  
Tue, Nov 27 2001 10:36:02    Mail sent by radim.blazek@dhv.cz  
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From Radim Blazek <radim.blazek@dhv.cz>
Organization DHV CR
To grass5@grass.itc.it
Subject Re: [GRASS5] [bug #858] (grass) v.support/v.build bug identified!
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Date Tue, 27 Nov 2001 09:38:15 +0100
Resent-From neteler@itc.it
Resent-Date Tue, 27 Nov 2001 10:35:56 +0100
Resent-To grass-bugs@intevation.de
On Mon 26. November 2001 20:03, Request Tracker wrote:

I'm not sure if this is realy v.build bug. v.build is designed for building
topology from clean linework. Two polygons with duplicated boundary is
not clean. Unfortunately cleaning module v.spag is only reliable for '-i'
flag. 
My solution for those who have imported files with clean topology
(export from ArcInfo for example, not ArcView) and good computer 
(time consuming method):

v.drop input=bad output=bad.drop   
cp vector/dig_att/bad vector/dig_att/bad.drop  # sorry, no support for dig_att
files in v.drop
v.support map=bad.drop
v.spag -i map=bad.drop
v.build.polylines -c -o input=bad.drop output=bad.ok type=area

Result:
 Number of lines:   3
 Number of nodes:   2
 Number of areas:   2
 Number of isles:   1
 Number of atts :   2
 Number of unattached atts :   0
 Snapped lines  :   0

This should reduce size of the vector (areas) to one half also.

v.drop: http://www.raz-dva.cz/krakonos/v.drop.tar

Radim


> this bug's URL: http://intevation.de/rt/webrt?serial_num=858
> -------------------------------------------------------------------------
>
> Subject: v.support/v.build bug identified!
>
> grass downloaded at: CVS Server, Germany
>
> The v.support/v.build bug with causes the PNT_TO_AREA failed warnings
> seems to be identified.
>
> A micro-demo-location to reproduce the problem is available at
> http://mpa.itc.it/markus/tmp/
>
> The location contains to sample vector maps "good" and "bad",
> each with two polygons only:
>
> GRASS:~/grassdata/patdemo > l
> total 12
> drwxr-xr-x    2 neteler  ssi          4096 Nov 26 19:49 PERMANENT
> drwxr-xr-x    2 neteler  ssi          4096 Nov 26 19:52 rawdata
> drwxrwxrwx    7 neteler  ssi          4096 Nov 26 19:55 vector
>
> In rawdata are the ARC-ASCII vector files and two import
> scripts:
>
> GRASS:~/grassdata/patdemo > ls -la rawdata
> total 40
> drwxr-xr-x    2 neteler  ssi          4096 Nov 26 19:52 .
> drwxr-xr-x    5 neteler  ssi          4096 Nov 26 19:51 ..
> -rw-r--r--    1 neteler  ssi            35 Nov 26 19:51 BadExample.dat
> -rw-r--r--    1 neteler  ssi            67 Nov 26 19:51 BadExample.pnt
> -rw-r--r--    1 neteler  ssi           273 Nov 26 19:51 BadExample.pol
> -rw-r--r--    1 neteler  ssi            35 Nov 26 19:51 GoodExample.dat
> -rw-r--r--    1 neteler  ssi            67 Nov 26 19:51 GoodExample.pnt
> -rw-r--r--    1 neteler  ssi           273 Nov 26 19:51 GoodExample.pol
> -rwxr-xr-x    1 neteler  ssi           154 Nov 26 19:52
> import.BadExample.sh -rwxr-xr-x    1 neteler  ssi           159 Nov 26
> 19:52 import.GoodExample.sh
>
> Now the GRASS bug: v.support writes
> PNT_TO_AREA failed: (1681015.000000, 5118635.000000) (Category 694020)
> PNT_TO_AREA failed: (1680445.000000, 5118795.000000) (Category 54014)
>
> when two or more polygons have the same starting point (the "bad" map).
> The identical "good" map with rotated nodes runs well.
>
> That may be the key to understand all the E00 and SHAPE problems
> which are regularly reported.
>
> Thanks to Lorenzo Potrich (ITC-irst) for identifying this problem.
>
> Please someone may fix this severe problem...
>
> Markus Neteler
>
>
> -------------------------------------------- Managed by Request Tracker
> _______________________________________________
> grass5 mailing list
> grass5@grass.itc.it
> http://grass.itc.it/mailman/listinfo/grass5
_______________________________________________
grass5 mailing list
grass5@grass.itc.it
http://grass.itc.it/mailman/listinfo/grass5


Fri, Mar 22 2002 09:56:18    Mail sent by mneteler  
after discussion with Radim I think it is a data problem (import
of non-topological data). v.support should be mostly fine.

Markus
Fri, Mar 22 2002 09:56:21    Status changed to resolved by mneteler  
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