donuts - Vector format flaw!(?)

[Malcolm Williamson]

Allan Axon writes:
> 
> Using 4.0,
> one problem I have encountered in going from vector to raster is handling
>  "donuts" of category 0:
> 
>              ____________
>             |   _____    |
>             |  |__0__| 1 |
>             |____________|
> 
> When rasterized, the above situation, gives
> 
>             1111111111111          11111111111
>             1111111111111    not   11100000111
>             1111111111111          11111111111
> 
> There are ways to work around this, but vector maps still have to be
> examined in order to recognize the presence of similar conditions.
> 
> Has this problem already been addressed in 4.1?
> 

Did you run v.support before doing the v.to.rast conversion? Granted, I'm 
using 4.1, but these are the results I get:

		 __________
		|  _____   |
		| |__0__| 1|
		|__________|

gives me 

	111111111
	110000111
	111111111

*as long as* the attribute point is within the "1" area, not the "0" area. If 
the attribute point is within the "0" area, even though I select the outer
polygon as the area boundary, I get:

	000000000
	001111000
	000000000  !!!

This seems pretty reasonable to me, if not terribly convenient!

-- 
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