Hi Jacques,

as someone who can do programming, I usually write simple programs that generate 3-D shape files. E.g. you can do this in Java using the GeoTools library (see geotools.org), which is open-source. E.g., in the scope of my projects, I export 3-D triangles (i.e. "not just 2.5-D", so that multiple z-values might be assigned to a location ) as polygons to ArcGIS Map or ArcGIS Pro.

In case you are interested: The source code is freely available under https://github.com/52North/GeologicToolbox/tree/master/triturus/src/main/java/org/n52/v3d/triturus/geologic/exporters)

Feel free to get in touch with me, if we can help you!

Kind regards, Benno

I used this procedure for pointz geometry but I think it will work for polylines too

Using QGIS databasemanager (or any spatial sql db) try this:

select GeomFromText('POLYGONZ ('|| x0 || ' ' || y0 || ' ' || z0 || ',' || x1 || ' ' || y1 || ' ' || z1 || ', ' ....... || xn || ' ' || yn || ' ' || zn || ',' || x0 || ' ' || y0 || ' ' || z0 || ',)', yourSRCHere ), item1, ..itemN from yourCSVTable

x,y,z are your coordinates. POLYGONZ can also be POLYGON Z depending the software you will use. It must generate a polygonz geometry then you can save it as shapefile. Remember, you must close the polygon, that is the reason why coordinates start and end with x0,y0,z0.

Good Luck!!!

Jacques Bodin 3D polyline function is available in QGIS which is open-source software.