On Fri, 19 Jun 2015 08:28:56 -0400, Anna Petrášová <[email protected]> wrote: > On Fri, Jun 19, 2015 at 7:48 AM, Moritz Lennert < > [email protected]> wrote: > >> I have the feeling I'm missing something, here, and I prefer asking the >> question here before posting a possible bug report. >> >> What is the exact meaning of zrot in v.transform ? I would have thought >> that with no scaling and no shift, zrot would create a simple rotation. >> >> I create a square as such: >> >> v.in.lines in=- out=testline sep=, --o << EOF >> 610000,200000 >> 680000,200000 >> Nan,Nan >> 680000,200000 >> 680000,270000 >> Nan,Nan >> 680000,270000 >> 610000,270000 >> Nan,Nan >> 610000,270000 >> 610000,200000 >> EOF >> >> I then try to rotate that squate by 45 degrees: >> >> v.transform input=testline output=testline45 zrotation=45 >> >> The result is shown the attached image: The rotation works, but I get a >> shift of about 445km NW. Is this expected ? > > > I think the rotation axis is in (0, 0), I would say that is expected > behavior, although should be better documented.
Yes, that does make sense. So if I want to rotate a specific feature, I have us translation to center it on (0,0), then rotate it and then translate it back ? Would probably be nice to have 'rotate' as a tool in v.edit... Thanks for the quick response ! Moritz _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
