[GRASSLIST:7873] Re: Vector Class -> Raster Class (big image)
Zaboj Hrazsky, DAPHNE CR
zaboj.hrazsky at daphne.cz
Thu Aug 11 16:23:51 EDT 2005
Jonathan Greenberg napsal(a):
> Ok, so I have a vector file with a bunch of attributes, some of which are
> class names. I want to convert this vector coverage to a raster image based
> on one of the attributes, where the attribute classes get converted to an
> integer (I can manually create an integer field, if this makes it more
You need prepare the column manualy
How do I go about this?
*v.to.rast* needs integer or floating point type
> A second issue is that this is going to output a rather massive raster
> (probably ~ 7gb), forgetting about 64-bit issues for a minute, does anyone
> know if the vector-> raster conversion is optimized (e.g. Does it create the
> raster row by row or is it going to attempt to load the entire raster into
> memory?), or am I going to see this choke?
I heart GRASS process the raster file row by row (r.mapcalc), hope v.to.rast works the same way.
I tried v.to.rast on 90000x55000 raster from 17000 polygon vector, it took 1,5 hour on P4 2 GHz, 512 RAM :-) (but only a few minutes on ArcGIS :-( ).
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