On Fri, Apr 19, 2013 at 9:06 AM, Mark Wynter <[email protected]> wrote: > Hi All, we're looking for ways to speed up the cleaning of a large OSM road > network (relating to Australia). We're running on a large Amazon AWS EC2 > instance. > > What we've observed is exponential growth in time taken as number of > linestrings increases. > > This means it's taking about 3 days to clean entire network. > > We were wondering if we were to split the dataset into say 4 subregions, and > clean each separately, is it then possible to patch them back together at the > end without having to run v.clean afterwards? We want to be able to run > v.net over the entire network spanning the subregions. > > Alternatively, has anyone found a way to speed up v.clean for large network > datasets?
Yes, implemented in GRASS 7 ;-) Also, when breaking lines it is recommended to split the lines first in smaller segments with v.split using the vertices option. Then run v.clean tool=break. After that, use v.build.polylines to merge lines again. Or use in GRASS 7 the -c flag with v.clean tool=break type=line. The rmdupl tool is then automatically added, and the splitting and merging is done internally. Markus M > > > > > GRASS 6.4.3svn (road_network):/data/grassdata > v.clean input=osm_roads > output=osm_roads_cleaned tool=break,rmdupl > -------------------------------------------------- > Tool: Threshold > Break: 0.000000e+00 > Remove duplicates: 0.000000e+00 > -------------------------------------------------- > Copying vector lines... > Rebuilding parts of topology... > Building topology for vector map <osm_roads_cleaned>... > Registering primitives... > 971074 primitives registered > 13142529 vertices registered > Number of nodes: 1458192 > Number of primitives: 971074 > Number of points: 0 > Number of lines: 971074 > Number of boundaries: 0 > Number of centroids: 0 > Number of areas: - > Number of isles: - > -------------------------------------------------- > Tool: Break lines at intersections > > > _______________________________________________ > 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
