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Curve geometries in GPKG/Spatialite are ignored by filtering #1

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kannes opened this issue Dec 8, 2022 · 4 comments
Open

Curve geometries in GPKG/Spatialite are ignored by filtering #1

kannes opened this issue Dec 8, 2022 · 4 comments
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@kannes
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kannes commented Dec 8, 2022

The Spatialite-based sqlite dialect of GDAL/OGR as used by QGIS when filtering GPKG or Spatialite layers can not handle some more complex curved geometries. For example MultiSurface(CurvePolygon(CompoundCurve(CircularString(...) as you might find in ALKIS data.

If such geometries exist in a layer to be filtered, they are ignored by the filter.

https://gis.stackexchange.com/questions/446768/working-with-circularstring-in-ogrs-sqlite-dialect has some tests with ogrinfo in it.

The upstream ticket in Spatialite is https://www.gaia-gis.it/fossil/libspatialite/tktview/cfa630d01b9baf56d663ed991f630de807477f6e

A possible workaround is linearizing the affected datasets using the "Segmentize by maximum angle" processing tool. An angle of 4° would match what GDAL/OGR's -nlt CONVERT_TO_LINEAR or other linearization of curves seems to use. This is a lossy process though and thus might not be desirable.

@kannes kannes added the upstream label Dec 8, 2022
@kannes
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kannes commented Jan 25, 2023

For now we will add a warning message @pgipper

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kannes commented Feb 6, 2023

Apparently this affected all kinds of curve geometries so #7 does that.

@kannes kannes changed the title Complex curve geometries in GPKG/Spatialite are ignored by filtering Curve geometries in GPKG/Spatialite are ignored by filtering Feb 7, 2023
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kannes commented Jul 18, 2023

Spatialite uses Google Groups as "mailing list" which cannot be used without a Google account. I mailed Alessandro Furieri directly on 2023-07-17 to ask about a estimate of the work required and potential sponsorship.

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kannes commented Jan 29, 2024

Aww, the existing ticket was closed.

sandro added on 2023-07-23 13:27:40:
I'm sorry, but I really don't think CIRCULARLINESTRINGS etc will ever be supported by SpatiaLite, at least not in the near future.
it is a demanding modification that would certainly have a very heavy impact on the project, and unfortunately the available resources are decidedly scarce.

If you are reading this and if you might be able to contribute to a significant funding, please contact me.

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