How can I convert raster (stream segments result of a watershed analysis) to vector polylines, preferably shapefile. In ArcGIS this is easily acomplished with the Raster to Polyline tool. I only see Polygonize (Raster to Vector) tool under the Raster -> Conversion menu.


If you are using QGIS with GRASS support you can:

  1. Use r.reclass reclass all the stream segments to 1 and everything else to nodata.
  2. use r.to.vect to convert the value of 1 to line, and line is default output. If one says you need GRASS 7 just use the other.

enter image description here

| improve this answer | |
  • Just run that and it crashed. I will download grass itself and try in GRASS. I was trying version 7 on a different machine and just about every function in GRASS was crashing so I am hoping that in Windows 7 i will have better luck. So far my QGIS/GRASS experience is such - constant crashing. – Jakub Sisak GeoGraphics Dec 22 '15 at 15:31
  • Just use osgeo4w – If you do not know- just GIS Dec 22 '15 at 15:45

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.