[GRASS-user] converting lines to polygons

[Bryan Keith]

> On 09/22/2010 02:40 PM, Bryan Keith wrote:
>>> On 09/22/2010 12:45 AM, Bryan Keith wrote:
>>>
>>>> Hello,
>>>>
>>>> I'm using these commands:
>>>>
>>>> v.clean input=test_ln output=testclean_ln tool=snap,bpol thresh=0.2,0
>>>> v.type input=testclean_ln output=testclean_bnd type=line,boundary
>>>> v.centroids input=testclean_bnd output=testclean_py
>>>>
>>>> trying to convert a bunch of lines to 5 polygons.  I've tried lots of
>>>> variations of v.clean including many snap thresholds, but I can only
>>>> get
>>>> 3
>>>> polygons.  Is there something I'm doing wrong?
>>>>
>>>>
>>> If it's only two missing, then just manually add centroids to those two
>>> areas that are not yet polygons. (using v.digit)
>>>
>> Well, it's two in this simple little example clipped from a larger file,
>> and I have lots of files to process so I'm looking for an automated
>> process.
>>
>>
> Can you figure out why other areas were not closed? Maybe you need a
> larger threshold value?
> By opening the vector with v.digit you'll see by the color coding of the
> nodes which are part of closed boundaries (dark green) and which are on
> a "broken" boundary (red).
> You'll also see quickly where you have centroids inside correct
> boundaries, and where you're missing them.

No, I can't figure out why the other areas were not closed.  A larger
threshold value does not help.  I have never used v.digit, and I actually
can't get anything to display with v.digit  Hmmm, I'm not sure what I'm
doing wrong with v.digit

I would be nice to be able to see where nodes aren't connected (I'm
guessing that's the problem) and be able to measure how far apart they are
from each other.  I'm surprised how increasing the threshold makes some
boundaries that were correct incorrect.

>
>> Bryan
>>
>>
>>>> Check out the line and polygons here:
>>>>
>>>> http://www.ideotrope.org/~bryan/lines.png
>>>> http://www.ideotrope.org/~bryan/polygons.png
>>>>
>>>> Bryan
>>>>
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>>>>
>>>>
>>>
>>> --
>>> Micha Silver
>>> Arava Development Co. +972-52-3665918
>>> http://surfaces.co.il
>>>
>>>
>>>
>>>
>>
>>
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>>
>>
>
>
> --
> Micha Silver
> Arava Development Co. +972-52-3665918
> http://surfaces.co.il
>
>
>