[Qgis-user] How to convert raster routes into vector format?

[Nick Papadonis]

Hi Håvard,

I found the raster calculator and read the online manual for it, however am still a bit lost.  I was also playing with the Style properties and color bands last night to try to accomplish this.  I was unable to get a single binary image with the single color (red in this case).  I think the understand the r.thin suggestion and that it will thin the single color thick lines for vectorization.  Appreciate if you can expand on obtaining a binary skeleton of the one color of the trails.

Thanks again,
Nick

> On Jul 29, 2015, at 7:18 AM, Havard Tveite <havard.tveite at nmbu.no> wrote:
> 
> If you are going to use GRASS r.to.vect (for instance through QGIS
> Processing), you will need a binary skeleton image.
> You could get one by using the raster calculator to extract
> your single colour as a binary image, and then GRASS r.thin
> (available in QGIS Processing) to get the skeleton.
> 
> Håvard
> 
> On 29/7/2015 8:36:AM, Nick Papadonis wrote:
>> Hi Folks,
>> 
>> I have a map with numerous trails in a single color and would like to vectorize these.  Is there a mode Qgis can be placed in such that a color can be selected for inclusion in the vectorization process?  I.e. to make converting these routes to vector format easier?
>> 
>> Thanks again
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