I'm trying to segment a topographic map to vectorize it. I'm using the watershed algorithm of SAGA-GIS. It's working fine with polygons, but with roads or contour lines is not working properly.

Here is an example about I refer... the countour lines have differents seed values...

  • Anyone knows how could I improve it to obtain clear lines?
  • Anyone knows how to remove the square appearance after vectorization?

Contour Lines after Watershed segmentation