[gdal-dev] Spatialite geometry format

[Even Rouault]

Selon Simon Lyngby Kokkendorff <silyko at gmail.com>:

> Hi List,
>
>    I am programming an application which can transform ogr-datasources
> (using our own transformation library). In that process I use ogr (version
> 1.10)  via the c-api to read and write datasources - usually it works like
> a charm. However, when I try to write an output spatialite datasource, I
> run into this error:
>
> sqlite3_step() failed:
>
> points2.GEOMETRY violates Geometry constraint [geom-type or SRID not
> allowed] (19)
>
>
> I am not sure whether it's an issue with the SRID or the geom-type /
> format. I also see on the ogr-drivers page, that spatialite use a speciel
> (wkb like?) format for the geometry column.

Yes, but this is an implementation detail from the point of view of users of
OGR, that is hidden by the OGR API.

>
>
> What I usually do is to clone an input feature, clone the geometry:
>
>
> hGeometry = OGR_G_Clone(OGR_F_GetGeometryRef(hFeature_out));
>
>
> perform some transformations and set the geometry (again):
>
>
> OGR_F_SetGeometryDirectly(hFeature_out,hGeometry);
>
>
> While this works for (most) input and output datasources, it produces the
> error above for spatialite output. Perhaps because the internal geometry
> reperesentation is wrong, or there is some other more strict check of
> output srs - e.g. should I use  OGR_G_AssignSpatialReference to assign the
> output spatial reference to the geometry?
>
>
> Is there something obvious that I am missing here?

The driver takes responsibility of assigning the SRID automatically from the
layer SRS. So the error is likely due to an attempt of inserting a geometry
whose type doesn't match the layer geometry type. Spatialite is really strict on
that: POLYGON != MULTIPOLYGON, and (perhaps I'm not sure) 2D != 2.5D

>
>
> Best Regards,
>
> Simon Kokkendorff,  Danish Geodata Agency
>