v.to.rast conversion

[Malcolm Williamson]

> 
> I have been attempting to convert a
> vector area layer to a raster layer using
> v.to.rast.  The problem I am having is
> that the vector layer contains a polygon
> that is wholly encloses by another
> polygon.  When executing a d.what.vect,
> the proper attribute value is returned
> for this lake.  However, after the
> conversion, the raster layer has "no
> data" for the lake.  Is this a known
> problem with v.to.rast?  I have checked
> for overlapping areas and there are none.
> I was able to circumvent the problem by
> importing the lake separately and doing
> an r.patch.  This seems like a roundabout
> way of doing it.  Any comments would be
> appreciated.
> 
> John Sparco
> 

First, in v.digit, make sure that the attribute point for the outer area is not
located within the inner "lake". If that looks ok, I'd suggest running v.support
on the file again, and then running v.to.rast one more time to test it. Data
"islands" in vector files tend to cause grief if they haven't had topology
rebuilt after doing *anything* to the file!! Let me know if this works for you.

Regards,
-- 
Malcolm D. Williamson - Research Assistant       E-mail: malcolm at cast.uark.edu
Center for Advanced Spatial Technologies      Telephone: (501) 575-6159
Ozark Rm. 12                                        Fax: (501) 575-3846 
University of Arkansas              
Fayetteville, AR 72701