[GRASS-user] V.overlay very slow

[incanus]

Thanx again Markus, you always saving me :D

patch followed by v.clean with break,rmdupl and later v.build make it really
fast!



Markus Metz-2 wrote:
> 
> If you just want to create one big vector with all features present in 
> several other vectors, try v.patch followed by v.clean.
> 
> For cleaning after patching areas, you will need at least to break 
> polygons and remove duplicates. If topology is still not correct, try 
> cleaning small angles at nodes followed by breaking lines, then remove 
> duplicates. If topology is still not correct, snapping vertices may be 
> necessary, here try a very small threshold first. Also see the v.patch 
> manual.
> 
> Hope that helps,
> 
> Markus
> 
> 
> incanus wrote:
>> Hi all,
>> I'm trying to join a large set of "vectorial tiles" that i have, into a
>> unique vectorial map. What i'm doing is something like this, for each
>> "tile"
>> (in the example is called filaN):
>>
>> v.overlay ainput=sumaFilas atype=area alayer=1 binput=fila6 btype=area
>> blayer=1 output=sumaFilas2 operator=or olayer=1,0,0
>> v.db.addcol map=sumaFilas2 layer=1 'columns=union INTEGER'
>> v.db.update map=sumaFilas2 layer=1 column=union value=1 
>> v.dissolve input=sumaFilas2 output=sumaFilas2 layer=1 column=union
>> --overwrite
>> g.remove vect=sumaFilas
>> g.rename vect=sumaFilas2,sumaFilas
>>
>> At first, the v.overlay is instant, but when processing the map number
>> 100,
>> it can be several hours.
>>
>> Anyone knows an alternate way to do this?
>> The first solution I adopted was making this by rows of 100 "tiles", and
>> then joining the rows (what i'm doing in the example above). It worked
>> for
>> me since i only has todo a "small" map (1 week of processing), but now i
>> need to do one MUCH more big.
>>
>> Thanx in advance if anyone knows something.. or not :)
>> Andres
>>   
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