Error using v.support

[R.Kunkel]

Steve,

I've got similar problems when importing ARC/INFO UNGENERATE vector data into
GRASS. We found out that these errors may occur, when two neigboring polygons
have identical starting points (first coordinate pair). Due to approximations,
which were made internally during building of the topology with v.support, it
may happen that the generated node of one area is located within the other
area. This leads to the error message you have mentioned. The problem is that
you can't see this e.g. with v.digit, because it is done only internally.
The problem can be solved by permutation of the starting point of either one of
these polygons. Then, two different nodes will be generated and the area labels
will be assigned correctly. We have written a program, which performs such a
permutation for all polygons given in ARC/INFO UNGENERATE format. Although the
program works fine, at present, there are still some small bugs in our program
concerning the iteration process. Thus, it it necessary to call the program
over and over, until all identical starting points are removed. Nevertheless,
if you would like to get this program, please send me a mail. Right after
fixing, I can put this program on moon additionally, if there's interest.

-- 
Dr. Ralf Kunkel                         Tel: ++49-2461-613262
Forschungszentrum Juelich GmbH          Fax: ++49-2461-612540
Programmgruppe Systemforschung und      EMail: r.kunkel at kfa-juelich.de
Technologische Entwicklung (STE)
D-52425 Juelich, Germany