[GRASS-user] v.external and region bounding box

Pietro peter.zamb at gmail.com
Thu Oct 18 03:10:53 PDT 2012

Hi all,

I have imported the Openstreetmap data of Italy[0] into a
Postgis/Postgres, using imposm[1].
Below are reported the table size in postgis:

         Name         | Type  | Owner |  Size   |
 osm_buildings        | table | osm   | 805 MB  |
 osm_landusages       | table | osm   | 202 MB  |
 osm_mainroads        | table | osm   | 105 MB  |
 osm_minorroads       | table | osm   | 447 MB  |
 osm_motorways        | table | osm   |  12 MB  |
 osm_railways         | table | osm   |  12 MB  |

I'm using GRASS7. I connected this layers using:

v.external dsn="PG:dbname=osm" layer=osm_*

Even if my region is pretty small, around 9km x 14km, GRASS it's very
slow to load and show the data into the MapDisplay, It seem like all
the vector features are loaded without take into account the region.

If I open the same layers with QGIS, with almost the same region
dimension it's very fast to load/show the data, probably QGIS load
only the features that are in the bounding box.

How can I say to v.external to load only the geometry features that
are in the region boundingbox?

Should I do this manually, making new tables?


ps: v.external return a Segmentation fault when I try to build the
pseudo-topology for the osm_buildings:

GRASS 7.0.svn (UTM32_WGS84):~ > v.external dsn="PG:dbname=osm"
layer=osm_buildings --overwrite
WARNING: Vector map <osm_buildings> already exists and will be overwritten
Building topology for vector map <osm_buildings at dtm_lidar>...
Using external data format 'PostgreSQL' (feature type 'geometry')
Building pseudo-topology over simple features...
Registering primitives...
Segmentation fault

[0] http://download.geofabrik.de/openstreetmap/europe/italy.osm.pbf  ~530 Mb
[1] http://imposm.org/docs/imposm/latest/

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