[gdal-dev] Re-projecting with valid geometry

[klo uo]

Hi,

I have PostGIS table with multipolygon geometry column of ~2000 features
with valid geometries. Most are single polygons.
These were originally in 900914 projection.

I tried to re-project to 4326, first with org2ogr then with PostGIS's
ST_Transform() function.

In both cases I get results with couple of invalid geometries in a manner
of:

  segment [#] of ring [#] of polygon [#] intersects segment [#] of ring [#]
of polygon [#] at [x], [y]

reported by QGIS "Check geometry validy" function, or same as a result from
PostGIS's ST_IsValid() function.

Interestingly table reprojected with ogr2ogr shows errors on different
features then errors generated by PostGIS's ST_Transform() function.

I wonder if there are some steps I can take before re-projecting or
afterward, that will produce valid transformation, without need of
correcting erroneous geometries by hand after re-projecting data?


Thanks
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20140906/0996896e/attachment.html>