[gdal-dev] How to get the same behaviour as the 'Difference tool' of QGIS, in ogr2ogr?

[Devdatta Tengshe]

Thanks a Ton, Ujaval!

The following command gave me the expected output:
`ogr_layer_algebra.py ERASE -input_ds line.shp -method_ds polygon.shp
-output_ds output.shp`


Regards,
Devdatta


On Wed, 10 May 2023 at 13:30, Ujaval Gandhi <ujaval at spatialthoughts.com>
wrote:

> There's a new script for doing vector overlays called ogr_layer_algebra.
> You can try that https://gdal.org/programs/ogr_layer_algebra.html
> <https://mailtrack.io/trace/link/8844f1b0a00bc9c8c6b7d994f2ef6776bbbad413?w=ZGV2ZGF0dGFAdGVuZ3NoZS5pbg&url=https%3A%2F%2Fgdal.org%2Fprograms%2Fogr_layer_algebra.html&userId=8747767&signature=f3a663794cf05dc3>
> ---
> Ujaval Gandhi
> Spatial Thoughts
> www.spatialthoughts.com
> <https://mailtrack.io/trace/link/4ddad0f9cf2b5c3c4c75c835dbf4a885ea30591b?w=ZGV2ZGF0dGFAdGVuZ3NoZS5pbg&url=http%3A%2F%2Fwww.spatialthoughts.com&userId=8747767&signature=de7d85fbbe1e0bcd>
>
>
>
> On Wed, May 10, 2023 at 1:26 PM Devdatta Tengshe <devdatta at tengshe.in>
> wrote:
>
>> I have a shapefile with lines, and another with polygons. I want to
>> generate an output of those lines that are not covered by any polygon.
>>
>> I can perfectly do this in QGIS's Difference tool, but want to do it with
>> og2ogr. (since it will be a part of a cronjob)
>>
>> I tried to do it, using the following command:
>> `ogr2ogr -overwrite out.shp line.shp -dialect SQLite -sql "select
>> st_difference(a.geometry, b.geometry) as geometry from line as a,
>> 'polygon.shp'.polygon as b"`
>>
>> But it just generated a .dbf file.
>>
>> This behavior has also been reported here:
>> https://gis.stackexchange.com/a/324837/442
>>
>> Is this a bug, or expected behavior? Is there a better way to achieve
>> what I want to?
>>
>>
>> Regards,
>> Devdatta
>> _______________________________________________
>> gdal-dev mailing list
>> gdal-dev at lists.osgeo.org
>> https://lists.osgeo.org/mailman/listinfo/gdal-dev
>>
>
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