[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
> complicated).

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 :-( ).

    Záboj Hrázský
    DAPHNE ČR - Institut aplikované ekologie
    Husova 45, 370 05 České Budějovice
    Tel: +420 776053573
    ICQ: 332817882


More information about the grass-user mailing list