About v.to.rast

[Malcolm Williamson]

On Thu, 1 May 1997, Venkatesh Raghavan wrote:

> Hello,
> Can anyone please tell me where I can find some information about the
> algorithm used in the GRASS program v.to.rast.
> Thanks in advance
> -- 
> --------------------------------------------------------------------------------
> $B%Y%s%+%F%C%7%e(J $B%i%,%o%s(J			Venkatesh Raghavan
> $BBg:e;TN)Bg3X3X=Q>pJsAm9g%;%s%?!<(J	Media Center, Osaka City Univ.
> $B#3!<#3!<#1#3#8?yK\=;5H6hBg:e(J $B#5#5#8(J	3-3-138 Sugimoto Sumiyoshi-ku, Osaka
> 558
>                   Tel:06-605-3381      
> mailto:raghavan at media.osaka-cu.ac.jp
> #################################################################################
> 
If you're just looking for the basics, I can help you out. For "line" 
conversions, any cell (at your current region resolution)  that a line 
passes through is tagged with the value of the vector line. Oops, almost 
forgot - all vector features must be attributed (numbered) to convert to 
raster. For "area" conversions, cells take the attribute of whatever 
vector polygon the _center_ of the cell corresponds to. To picture this, 
draw a circle on top of some graph paper. Color in any square that has 
its center within the circle; the result is a raster representation of 
the circle as an area. To visualize the line conversion, do the same 
thing, but color in every cell that the circle crosses. Hope this helps!
--
Malcolm D. Williamson - GIS Specialist           E-mail: malcolm at cast.uark.edu
Center for Advanced Spatial Technologies      Telephone: (501) 575-6159
Ozark Rm. 12                                        Fax: (501) 575-5218 
University of Arkansas              
Fayetteville, AR 72701