[GRASSLIST:2647] Re: eliminating stream fragments

[Christopher Fonnesbeck]

On Feb 11, 2004, at 5:02 AM, Radim Blazek wrote:

>> There have been posts recently about how to remove polygon islands; on
>> a related note, I am wondering what is the best method for removing
>> line fragments from a stream coverage. That is, bits of the stream
>> coverage that are isolated from the main network due to the
>> accumulation threshold value specified in the generation of the stream
>> network. It doesnt look like v.clean does this, but please correct me
>> if I'm wrong.
>
> v.clean tool=rmdangle removes 'dangles', i.e. lines with one free end.
> This tool is intended for cleaning of boundaries. If you use it for
> river network, it removes also short lines connected to network.
> The tool you need should be added to v.clean tools.
>
> I thing, that v.net.alloc (http://mpa.itc.it/radim/g51/v.net.alloc.png)
> can help you. Place just one point at any node of the network
> and use its category in ccats option, v.net.alloc will allocate
> whole connected network and isolated lines will be left without 
> category.

How does one "place points" with v.net.alloc? I have browsed the 
documentation, and assume it has something to do with the ccats 
argument, but am not clear what this argument does, based on the 
examples given in the html docs.

thanks,
Chris
--
Christopher J. Fonnesbeck ( c h r i s @ f o n n e s b e c k . o r g )
Georgia Cooperative Fish & Wildlife Research Unit, University of Georgia