Hi,
As far I know the the Spatialite functions
https://www.gaia-gis.it/gaia-sins/spatialite-sql-4.2.0.html by design work row
by row and one input row returns one output row. Therefore DissolvePoints
creates one row with a multipoint geometry, not several rows like ST_Dump does.
You can discuss about that in the spatialite-users forum
https://groups.google.com/g/spatialite-users.
It is possible to extract the points from linestrings with SpatiaLite SQL by
using NumPoints and then PointN in a loop, but such SQL is not possible to
execute with ogrinfo/ogr2ogr. It is possible to do amazing things with ogr2ogr
and SQL but it does make it the right tool for demanding ETL processes.
Typically people turn to use Python at that point.
If you have a real need to extract points from a linestring by using only GDAL
command line utilities, it should be possible to do in two steps. Create an
interim file by using the Spatialite function DissolvePoints, and then run
ogr2ogr with the -explodecollections option.
-Jukka Rahkonen-
-----Alkuperäinen viesti-----
Lähettäjä: gdal-dev <gdal-dev-boun...@lists.osgeo.org> Puolesta Dan Jacobson
via gdal-dev
Lähetetty: perjantai 31. toukokuuta 2024 8.36
Vastaanottaja: Daniel Baston <dbas...@gmail.com>
Kopio: gdal-dev@lists.osgeo.org
Aihe: Re: [gdal-dev] OGR SQL CAST geometry example
Alas, even for MULTIPOINT, as there are no facilities for extracting from
aggregates, not even ST_Dump, in the end all one can do is $ ogrinfo
0.lines.kml -al | perl -nwle \
'if(/LINESTRING.*\((.*)\)/){print for split /,/, $1}'
-100.790056666679 36.3802233333333 1000
-100.790080000013 36.38531 1000
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