On Fri, Oct 7, 2016 at 4:08 PM, Sam Snellings <[email protected]> wrote: > Fantastic, that worked perfectly. Thanks for taking a look at the data for > me. It didn't even occur to me that the data might have a third dimension. > > Is there an easy way to check whether a geometry/shapefile has a > Z-coordinate element in case I run into a similar issue in the future? I can > just test import as 2d as you recommend (or QGIS has an export function that > removes z-coordinates), but perhaps there is an easier way to tell?
the easiest way to tell if layer in a OGR-recognized datasource is 3D is to use ogrinfo -so <datasource_name> <layer>. For the data in question, it reports with gdal-2.1.1 (amongst other info) Geometry: 3D Line String Markus M > > -Sam > > On Thu, Oct 6, 2016 at 3:32 PM, Markus Metz <[email protected]> > wrote: >> >> On Wed, Oct 5, 2016 at 3:05 AM, Sam Snellings <[email protected]> >> wrote: >> > Markus, >> > >> > Thank you for the suggestions. I ran the following commands nine times >> > on >> > the data, with thresholds .00000000000000000001, 0.0000000001, >> > 0.0000001, >> > 0.00001, 0.01, 0.1, 1, 10, and 100. Let me know if I'm not going small >> > enough. >> > >> > v.clean --overwrite input=roads output=roads_snap -c tool=snap >> > thresh=[see >> > above] >> > v.net --overwrite input=roads_snap points=schools output=network >> > operation=connect thresh=1000 >> > v.net.alloc --overwrite input=network output=network_allocation >> > ccats=1-2 >> > >> > I did not get a complete allocation of road segments from any of them, >> > and >> > as far as I can tell it got stuck at the same vertices on each run. >> > >> > I will email you a link to the data off-list, thanks for taking a look. >> >> thanks for providing a link to the data! The problem is that the roads >> are 3D with z coordinates not matching at the end of a road segment >> and the beginning of another road segment. The solution is to import >> roads as a 2D vector with v.in.ogr -2. 2D snapping with v.clean >> tool=snap thresh =1 might be helpful. >> >> Markus M >> >> > >> > -Sam >> > >> > On Tue, Oct 4, 2016 at 3:53 PM, Markus Metz >> > <[email protected]> >> > wrote: >> >> >> >> On Tue, Oct 4, 2016 at 5:09 PM, Sam Snellings <[email protected]> >> >> wrote: >> >> > I've been running some trials through v.net.alloc using town road >> >> > networks >> >> > as the arc layer and schools as the node layer. I have one set of >> >> > roads/schools that breezes through v.net.alloc without issue (Town >> >> > 1), >> >> > while >> >> > another one only allocates the first few arcs connected to each >> >> > school >> >> > and >> >> > leaves the rest of the network unallocated (Town 2). There is >> >> > probably a >> >> > problem with the data from Town 2, but I can't figure out what it is. >> >> > Does >> >> > this issue sound familiar to anyone? >> >> > >> >> > I am using the GUI. I load each pair of shapefiles into GRASS and >> >> > then >> >> > run >> >> > the following statements (I only import two school points to >> >> > simplify). >> >> > The >> >> > two towns are pulled right from the state-wide GIS office, but the >> >> > towns >> >> > are >> >> > in different states (ie - different agencies provide the data). >> >> > >> >> You do not need this for v.net.alloc: >> >> > v.net input=roads output=road_nodes operation=nodes >> >> it will create a point for every node, the first point will have >> >> cat=1, the second cat=2 which collides with the points you want to >> >> attach >> >> >> >> > v.net input=road_nodes points=schools output=network >> >> > operation=connect >> >> > thresh=1000 >> >> >> >> rather use >> >> v.net input=roads points=schools output=network operation=connect >> >> thresh=1000 >> >> >> >> > v.net.alloc input=network output=network_allocation ccats=1-2 >> >> >> >> the real problem is probably a data problem: roads are not properly >> >> connected, i.e. the end of one road does not match the beginning of >> >> another road. Try v.clean input=roads output=roads_snap -c tool=snap >> >> with a very small threshold. This kind of error is quite common with >> >> shapefiles (not a fault of the shapefile format but of the software >> >> used to create the shapefiles). >> >> >> >> > >> >> > Thanks in advance for any advice, I can also email images/data if >> >> > that >> >> > would >> >> > be helpful. >> >> >> >> If v.clean -c tool=snap does not help, (links to) original data of the >> >> schools and road network for Town 2 would be helpful (data please only >> >> off-list). >> >> >> >> Markus M >> > >> > >> > >> > _______________________________________________ >> > grass-user mailing list >> > [email protected] >> > http://lists.osgeo.org/mailman/listinfo/grass-user > > _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
