[GRASS-user] Re: grass-user Digest, Vol 47, Issue 52

[Micha Silver]

Nathaniel Iwuchukwu wrote:
> here are the image results of my works. am trying to upload it on my page
If you do upload the images, post also to the list.

It looks like all the areas that are *not* roads are also being 
classified. Everywhere that appears purple in you classification image 
needs to be set to null. You do this with:
r.null <classified_raster> setnull=<the value which displays purple>

You want to be left with a raster with values *only* where there are 
roads. Everything else should be null. Then go ahead and run:
r.thin and r.to.vect <classified_raster_thin> feature=line out=roads

Cheers,
Micha
>
> 2010/4/1 Micha Silver <micha at arava.co.il <mailto:micha at arava.co.il>>
>
>     On 04/01/2010 02:52 PM, Nathaniel Iwuchukwu wrote:
>>     i created 11 polygons from different portions of the road.
>     So if I understand correctly, the procedure is working, but you're
>     not getting the results you'd expect?
>
>     Maybe you could supply to the grass-users list some URL's of
>     images of what the satellite rasters look like, with your training
>     polygons, and the resulting roads. Then perhaps someone will be
>     able to suggest how to get more complete results. 
>>
>>
>>      
>