I am trying to split a selected polygon ("regions") with a selected line from another layer ("streets") in QGIS 3.8.3. In the example below, I want to split the selected polygon coloured in yellow with the street pointed at by the blue arrow.
After reading the post Can't Find the Split selected features with selected line from another layer tool, I realized I can't find it either. I installed the plugin, but the tool seems to be missing from my toolbar:
In the Processing Toolbox under "Vector Overlay" use the "Split with lines" tool.
Just be wary that with such a complex line dataset this can cause some geometry issues, especially if you have any dangles. If it does then you could try using Fix Geometries or else Validate Geometry to try to fix any issues that pop up.
It might also be helpful to make doubly sure the geometries of both datasets are ok before actually doing the split.
This was no success for my layer which was imported from a DWG file, as the line segments are usually not connected at all in those kind of layers.
What worked for me is Polygonize in the Processing Toolbox. It does not split your existing polygon but creates a new layer with all the polygons which are enclosed by the lines of the another.
If you insist to get your original polygon splitted, it should be trivial to get that with common polygon operations.
use local coordinate systems for avoiding error, both vector and project crs should be in local cooordinates, or use polygonize command for closed polylines .
