Further efforts show that the distance upload is giving the correct value. I had the wrong flag checked (not as clear as it might be in the GUI). The other issues remain. But at least I CAN get useful analysis results.
Michael On May 23, 2012, at 4:49 PM, <[email protected]> wrote: > Send grass-dev mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.osgeo.org/mailman/listinfo/grass-dev > or, via email, send a message with subject or body 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of grass-dev digest..." > Today's Topics: > > 1. broken stuff in vector modules (Michael Barton) > 2. another bug in v.distance (Michael Barton) > 3. v.distance values bogus in GRASS 6.4.2 also (Michael Barton) > > From: Michael Barton <[email protected]> > Subject: [GRASS-dev] broken stuff in vector modules > Date: May 23, 2012 4:43:11 PM GMT+02:00 > To: GRASS developers grass-developers <[email protected]> > > > Hi, > > I don't use the vector modules a lot and so they don't get a lot of testing > from me. I'm trying to do a project with someone that uses vector module and > I find that some key things are broken. The following apply to GRASS 7 and > GRASS 6.4.3. > > 1) v.distance gives bogus results for point to line distance uploads in a > latlon region. For example, the distance uploaded from one site point to the > nearest waterway is 5767967.05475, yet measuring this with the distance tool > gives a much more reasonable 33211 m. The uploaded distance is off by an > order of 173X -- an enormous error. Nothing in the docs says that you cannot > use v.distance with latlon regions. > > 2) To get around this, I thought I'd try to get the length of the line that > connects each site point with its nearest waterway (a v.distance option). But > when I tried to make a new table for this in the table manager, I find that I > cannot access the "table description" section of the "manage layers" page in > the attribute table manager. This is again because wx.StaticBox needs to be > defined in a particular order or the Mac interface cannot access it. This has > been a recurrent problem with wx.StaticBox. The StaticBox must be > instantiated before any of its contents. > > 3) After creating a linked table using v.db.addtable instead of the attribute > manager, I tried to modify the layer in the attribute table manager, but only > received a message that "<flag> is not a valid value". Another bug. > > I did manage to get a length value into the lines connecting the points and > they are quite reasonable values. But of course I have no way that I can see > to link the distance lines back to the points from which they were created > with v.distance. So I still don't have analysis results and my colleague is > ready to try this in ArcGIS. > > Any suggestion for a workaround would be much appreciated. And of course, the > multiple bugs here need to be fixed. > > Michael > > _____________________ > C. Michael Barton > Visiting Scientist, Integrated Science Program > National Center for Atmospheric Research & > University Consortium for Atmospheric Research > 303-497-2889 (voice) > > Director, Center for Social Dynamics & Complexity > Professor of Anthropology, School of Human Evolution & Social Change > Arizona State University > www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu > > > > > > > > > From: Michael Barton <[email protected]> > Subject: [GRASS-dev] another bug in v.distance > Date: May 23, 2012 4:47:08 PM GMT+02:00 > To: GRASS developers grass-developers <[email protected]> > > > Forgot to mention that the table selection pull-downs do not work in any > version of the v.distance GUI--from 6.4.2 to 7.0 > > Michael > _____________________ > C. Michael Barton > Visiting Scientist, Integrated Science Program > National Center for Atmospheric Research & > University Consortium for Atmospheric Research > 303-497-2889 (voice) > > Director, Center for Social Dynamics & Complexity > Professor of Anthropology, School of Human Evolution & Social Change > Arizona State University > www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu > > > > > > > > > From: Michael Barton <[email protected]> > Subject: [GRASS-dev] v.distance values bogus in GRASS 6.4.2 also > Date: May 23, 2012 4:48:37 PM GMT+02:00 > To: GRASS developers grass-developers <[email protected]> > > > So the values for point to line distances are just as bad in GRASS 6.4.2 as > they are in GRASS 7. Any suggestions on how to get this information for a > latlon region? > > Michael > _____________________ > C. Michael Barton > Visiting Scientist, Integrated Science Program > National Center for Atmospheric Research & > University Consortium for Atmospheric Research > 303-497-2889 (voice) > > Director, Center for Social Dynamics & Complexity > Professor of Anthropology, School of Human Evolution & Social Change > Arizona State University > www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu > > > > > > > > _______________________________________________ > grass-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-dev _____________________ C. Michael Barton Visiting Scientist, Integrated Science Program National Center for Atmospheric Research & University Consortium for Atmospheric Research 303-497-2889 (voice) Director, Center for Social Dynamics & Complexity Professor of Anthropology, School of Human Evolution & Social Change Arizona State University www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu
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