[GRASS-user] magic?

[achim]

Its all about the resolution!

raster-resolution has effects on some vector-operations. It seems, that
eg. some tools in v.clean (problem getting correct areas from bounds,
adding centros after using v.clean).

The same is with v.to.rast, which is obvious. But converting the
formerly attached polygon works just in an higher resolution (g.region
res=0:00:05).

This higher resolution (and 0:00:10) was used to run some filters in
order to get a special buffer needed to combine areas with lines.

The question remains: why do some polygons be converted correctly? Same
with cleaning a vector and making areas? Is there a problem with averaging?

Best regards,
Achim

achim schrieb:
> sure, its the nile catchment at:
> 4326
> 
> projection: 3 (Latitude-Longitude)
> zone:       0
> datum:      wgs84
> ellipsoid:  wgs84
> north:      31:27:30N
> south:      4:01:30S
> west:       23:27E
> east:       39:48E
> nsres:      0:00:30
> ewres:      0:00:30
> rows:       4258
> cols:       1962
> cells:      8354196
> 
> 
> Milton Cezar Ribeiro schrieb:
>> Hi Achim,
>>  
>> could you, please, share with us your region -p  ?
>>  
>> bests
>>  
>> milton
>>
>> 2009/8/20 achim <ak7 at jupiter.uni-freiburg.de
>> <mailto:ak7 at jupiter.uni-freiburg.de>>
>>
>>     Hi,
>>
>>     I tried a lot. And I found a solution:
>>
>>     I made a buffer around the area with 0 distance. Then v.to.rast works.
>>
>>     If anyone knows why, it would be very interesting for me.
>>
>>     Moreover, when this happens in a big dataset, the error will probably
>>     not recognized.
>>
>>     Thanks for attention,
>>     Achim
>>
>>
>>     achim schrieb:
>>     > Hi,
>>     >
>>     > using a new location: no success
>>     >
>>     > export and import as shape-file: no success
>>     >
>>     > reproduce it with spearfish dataset: no success
>>     >
>>     > Has anybody an idea?
>>     >
>>     > I attach the problem-polygon as a shape... hope somebody has the same
>>     > problem with it ...and an idea.
>>     >
>>     > Thanks,
>>     > Achim
>>     >
>>     > achim schrieb:
>>     >> Hello,
>>     >>
>>     >> I used v.to.rast
>>     >>     v.to.rast --overwrite input=inmap output=outmap use=cat
>>     >> to convert 29 areas to raster.
>>     >>
>>     >> It says
>>     >>     Converted areas: 29 of 29
>>     >> but one area is missing!!!
>>     >>
>>     >> Its the one with cat number 16. Doing the same just for the
>>     selected 16,
>>     >> conversion results in am empty raster map.
>>     >>
>>     >> the same with use=attr or usr=val. Another vector map also does not
>>     >> convert some areas. The missing areas are not special
>>     >>
>>     >> What happens? Magic?
>>     >>
>>     >> I tried it with grass64 and newly compiled grass65. (OpenSuse
>>     11.1 64bit)
>>     >>
>>     >> Achim
>>     >>
>>     >> PS:
>>     >> Layer: 1
>>     >> Typ       Anzahl        Min        Max
>>     >> Punkt          0          0          0
>>     >> Linie           0          0          0
>>     >> Grenze       0          0          0
>>     >> Zentroid      29          1         29
>>     >> Fläche           0          0          0
>>     >> Alle           29          1         29
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>>     >>
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