I want statistics on the area that is further than 2,5m away from any border. I thought I could do this by creating a buffer of 2,5m around all polygons, then extracting the buffer area from the original dataset. I manage to create the buffer, but it is not a separate layer, and the polygons that are created are all multi-part with double lines.
When I select a polygon, I see the lines are overlapping, and I need the buffer lines to be separate polygons. I have tried using the multipart to singlepart tool, but it does not solve the problem. Neither does creating a union between the original layer and the buffer layer.
This is one example - here I have selected one polygon in the buffer layer(the original layer behind with grey lines, the buffer layer with see through background ad red lines, selected polygon marked with blue lines)::