Hi, I've imported a shapefile with 14 polygons using v.in.ogr: ----- v.in.ogr dsn=/media/0847147784/data/dwaf/liebenbergsvlei/myne/sa_tm_29_deg_east/C83A/c83a_14_subcatchments.shp output=test Datum <unknown> not recognised by GRASS and no parameters found Projection of input dataset and current location appear to match Layer: c83a_14_subcatchments Importing map 14 features... ----------------------------------------------------- Building topology for vector map <test>... Registering primitives... 14 primitives registered 16578 vertices registered Building areas... 7 areas built 4 isles built Attaching islands... Attaching centroids... Number of nodes: 9 Number of primitives: 14 Number of points: 0 Number of lines: 0 Number of boundaries: 14 Number of centroids: 0 Number of areas: 7 Number of isles: 4 Number of incorrect boundaries: 10 Number of areas without centroid: 7 ----------------------------------------------------- Cleaning polygons, result is not guaranteed! Building topology for vector map <test>... Number of nodes: 9 Number of primitives: 14 Number of points: 0 Number of lines: 0 Number of boundaries: 14 Number of centroids: 0 Number of areas: - Number of isles: - ----------------------------------------------------- Break polygons: ----------------------------------------------------- Remove duplicates: ----------------------------------------------------- Break boundaries: ----------------------------------------------------- Remove duplicates: ----------------------------------------------------- Clean boundaries at nodes: ----------------------------------------------------- Break boundaries: ----------------------------------------------------- Remove duplicates: ----------------------------------------------------- Clean boundaries at nodes: ----------------------------------------------------- Change dangles to lines: ----------------------------------------------------- Remove bridges: ----------------------------------------------------- Building topology for vector map <test>... Building areas... Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored 308 areas built 13 isles built Attaching islands... Number of nodes: 1221 Number of primitives: 3277 Number of points: 0 Number of lines: 0 Number of boundaries: 3277 Number of centroids: 0 Number of areas: 308 Number of isles: 13 Number of incorrect boundaries: 17 Number of areas without centroid: 308 Cannot calculate area centroid Cannot calculate area centroid Layer: c83a_14_subcatchments ----------------------------------------------------- ----------------------------------------------------- Building topology for vector map <test>... Registering primitives... 10001774 primitives registered 15588 vertices registered Building areas... Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored Area of size = 0.0 ignored 308 areas built 13 isles built Attaching islands... Attaching centroids... Number of nodes: 1447 Number of primitives: 1774 Number of points: 0 Number of lines: 0 Number of boundaries: 1539 Number of centroids: 235 Number of areas: 308 Number of isles: 13 Number of incorrect boundaries: 17 Number of duplicate centroids: 29 Number of areas without centroid: 102 ----------------------------------------------------- 196 areas represent more (overlapping) features, because polygons overlap in input layer(s). Such areas are linked to more than 1 row in attribute table. The number of features for those areas is stored as category in layer 2 14 input polygons Total area: 7.449545e+08 (308 areas) Overlapping area: 2.001273e-05 (196 areas) Area without category: 5.083098e-06 (71 areas) (Wed Nov 10 16:45:27 2010) Command finished (11 sec) -----
When I export the file to SHP again, it now contains 703 polygons: ----- v.out.ogr -e input=t...@permanent type=area dsn=/home/hanlie/ olayer=test The map contains islands. To preserve them in the output map, use the -c flag Exporting 308 areas (may take some time)... 703 features written 102 features without category were written (Wed Nov 10 16:47:55 2010) Command finished (0 sec) ----- When I import and select not to clean the polygons upon import, I get: ----- v.in.ogr -c dsn=/media/0847147784/data/dwaf/liebenbergsvlei/myne/sa_tm_29_deg_east/C83A/c83a_14_subcatchments.shp output=test Datum <unknown> not recognised by GRASS and no parameters found Projection of input dataset and current location appear to match Layer: c83a_14_subcatchments Importing map 14 features... ----------------------------------------------------- Building topology for vector map <test>... Registering primitives... 28 primitives registered 16592 vertices registered Building areas... 7 areas built 4 isles built Attaching islands... Attaching centroids... Number of nodes: 23 Number of primitives: 28 Number of points: 0 Number of lines: 0 Number of boundaries: 14 Number of centroids: 14 Number of areas: 7 Number of isles: 4 Number of incorrect boundaries: 10 Number of centroids outside area: 7 (Wed Nov 10 16:46:29 2010) Command finished (0 sec) ----- But the GRASS vector layer has only 7 areas. Does this indicate some flaw in my original data? Thanks Hnalie _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user