[GRASS5] [bug #858] (grass) v.support/v.build bug identified!

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this bug's URL: http://intevation.de/rt/webrt?serial_num=858
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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


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