[GRASS-user] converting lines to polygons

[Micha Silver]

On 09/23/2010 05:42 PM, Bryan Keith wrote:
>> 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
>    
What OS are you on? what version of GRASS, and what GUI?
> 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.
>    
Yes, Surprising. Can we see, as Markus M suggested, the output of v.info 
-t or v.clean? Also what units is your data in? i.e the output of v.info 
-g and g.region -p ?
Regards,
-- 
Micha
>    
>>      
>>> Bryan
>>>
>>>
>>>        
>>>>> Check out the line and polygons here:
>>>>>
>>>>> http://www.ideotrope.org/~bryan/lines.png
>>>>> http://www.ideotrope.org/~bryan/polygons.png
>>>>>
>>>>> Bryan
>>>>>
>>>>> _______________________________________________
>>>>> grass-user mailing list
>>>>> grass-user at lists.osgeo.org
>>>>> http://lists.osgeo.org/mailman/listinfo/grass-user
>>>>>
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>>>>>
>>>>>
>>>>>
>>>>>
>>>>>            
>>>> --
>>>> Micha Silver
>>>> Arava Development Co. +972-52-3665918
>>>> http://surfaces.co.il
>>>>
>>>>
>>>>
>>>>
>>>>          
>>>
>>> This mail was received via Mail-SeCure System.
>>>
>>>
>>>
>>>        
>>
>> --
>> 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