Re: [GRASS-dev] Satellite tiles: tiles missing after import?
On Thu, Dec 22, 2016 at 3:25 PM, Markus Neteler wrote: > > Hi, > > I imported both the WRS2 Landsat tiles [1] as well as the Sentinel-2 > KML [2] (giving extra issues during import + also querying due to > quoting issues). > > In both cases, when zooming into the map, some polygons are not drawn > in areas where the tiles massively overlap. > > I used the -c flag of v.in.ogr to not break the polygons but to keep > them intact. The -c flag is problematic: it does not break polygons, but polygons are converted to GRASS boundaries. Centroids have to be calculated for each output GRASS area. As a result, an output GRASS area corresponding to an input polygon might have multiple centroids or no centroid at all (these are the holes you see). Please do not use the -c flag with v.in.ogr unless you know exactly what you are doing and what you will get. Markus M > > Is that a GUI issue or a vector engine issue? > > [1] https://landsat.usgs.gov/pathrow-shapefiles --> wrs2_descending.zip > [2] https://sentinel.esa.int/documents/247904/1955685/S2A_OPER_GIP_TILPAR_MPC__20151209T095117_V20150622T00_21000101T00_B00.kml > > thanks, > Markus > ___ > grass-dev mailing list > grass-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/grass-dev ___ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev
Re: [GRASS-dev] Satellite tiles: tiles missing after import?
On Thu, Dec 22, 2016 at 6:39 PM, Martin Landa wrote: > Hi, > > 2016-12-22 15:25 GMT+01:00 Markus Neteler : >> I used the -c flag of v.in.ogr to not break the polygons but to keep >> them intact. > > number of boundaries and centroids will be correct (29 245). The input > shapefiles contains 28 892 features (some of them are multipolygons, > in the result 29 245 polygons). Building areas from uncleaned > boundaries (basically outer rings) cannot work, Vect_build_line_area() > will not able to report all neighbours. In the results GRASS builds > only 27 751 areas. So does this affect the display then? I see holes in the map where I would expect tiles (and QGIS shows them). thanks Markus PS: Sentinel-2 tiles in SHAPE format I found here: https://github.com/justinelliotmeyers/Sentinel-2-Shapefile-Index (probably better than the KML) ___ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev
Re: [GRASS-dev] Satellite tiles: tiles missing after import?
Hi, 2016-12-22 15:25 GMT+01:00 Markus Neteler : > I used the -c flag of v.in.ogr to not break the polygons but to keep > them intact. number of boundaries and centroids will be correct (29 245). The input shapefiles contains 28 892 features (some of them are multipolygons, in the result 29 245 polygons). Building areas from uncleaned boundaries (basically outer rings) cannot work, Vect_build_line_area () will not able to report all neighbours. In the results GRASS builds only 27 751 areas. Ma -- Martin Landa http://geo.fsv.cvut.cz/gwiki/Landa http://gismentors.cz/mentors/landa ___ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev
