[GRASS-user] OpenFileGDB input error

[Even Rouault]

On lundi 25 septembre 2017 19:19:26 CEST Markus Metz wrote:
> On Mon, Sep 25, 2017 at 6:07 PM, Rich Shepard <rshepard at appl-ecosys.com>
> 
> wrote:
> > On Mon, 25 Sep 2017, Markus Metz wrote:
> >> A multi-surface has sneaked into the layer with multi-polygons, that's
> >> causing the error in v.in.ogr.
> >> 
> >   Huh! In my naivity I would assume a surface is 3D and a polygon is 2D.
> > 
> > What I read suggests there are two layers; perhaps the surfaces are crop
> > type and the polygons are farm boundaries?
> 
> these multi-surfaces are in the layer with multi-polygons. OGR calls these
> geometries multi-surfaces.

Actually it is defined by
​OpenGIS Simple Feature Access Part 1 : Common Architecture,v 1.2.1 :
http://portal.opengeospatial.org/files/?artifact_id=25355

> Investigating a bit more, I found curve-polygons
> within these multi-surfaces. Curve-polygons are in turn not ordinary
> polygons, but defined by curves, and v.in.ogr (most GIS software in
> general) does not support curves.
> 

The relevant GDAL RFC is
https://trac.osgeo.org/gdal/wiki/rfc49_curve_geometries
Support for curves in FileGDB is more recent.

You can force a curve geometry to its linearized version (curves are approximated with 
segments) with:

hGeom = OGR_G_ForceTo(hGeom, OGR_GT_GetLinear(OGR_G_GetGeometryType(hGeom)))

Even

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