How to convert raster to polyline in QGIS?
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:
- Use r.reclass reclass all the stream segments to 1 and everything else to nodata.
- 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.