QGIS – How to Import CSV Data with WKT GEOMETRYCOLLECTION() to QGIS

csvgeometrycollectionqgiswell-known-text

I have a CSV file containing geodata in WKT in one column. The geometry type is GEOMETRYCOLLECTION. How do I import this to QGIS with one layer per geometry type (POINT and LINESTRING in this case)?

Here's a simplified feature example:

id,title,description,features,category,date
79042,Ausbau Wismar–Rostock,"Ich schlage einen zweigleisigen Ausbau und die Elektrifizierung Wismar–Rostock...","GEOMETRYCOLLECTION(POINT(11.474493907902323 53.89207715945744),LINESTRING(11.47502100706609 53.89112033371444,11.474763515000689 53.89162614941653))",Regionalverkehr,2023-03-24

I used Layer > Add Layer > Add Delimited Text Layer… in QGIS 3.22 and I can select either single geometry types or "Detect" for WKT. I would have expected a new window to select one or more geometry type layers to create from the source. But there is no such selection. An empty layer with no data is being created.

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It works if I split the geometry into one column for points and one for lines.

id,title,description,point,line,category,date
79042,Ausbau Wismar–Rostock,"Ich schlage einen zweigleisigen Ausbau und die Elektrifizierung Wismar–Rostock...","POINT(11.474493907902323 53.89207715945744)","LINESTRING(11.47502100706609 53.89112033371444,11.474763515000689 53.89162614941653)",Regionalverkehr,2023-03-24

But my original data has almost 15k rows, so the manual solution does not work. Also, it has more than one point and one linestring per feature.

Best Answer

I converted your data into GeoJSON and tried to open that with QGIS but it cannot read the geometry nor the attributes correctly. I believe that QGIS cannot really handle geometry collections.

As a workaround I suggest to pre-process the data with ogr2ogr first by exploding the geometry collections.

Usage example:

ogr2ogr -f GeoJSON geomcol.json geomcoll.csv -explodecollections -oo geom_possible_names=features

QGIS can open the resulting GeoJSON file and it suggest to create separate layers for each geometry type.

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