[GRASSLIST:3821] Re: Mask Concept

[Eric G. Miller]

On Mon, Jun 03, 2002 at 10:32:53AM +0530, Anil Kumar Bhagat wrote:
> Dear Grass user , 
>                   I donot have the concept of mask . Please anybody help
> me in understanding mask . What is this ? How is works . How to set or
> prepare new mask ? How is modules are directly related to mask or mask
> file . Sorry for this simple qustion ?

A mask allows you to block arbitrary areas of all rasters processed
while the mask is set.  That is, for cells where the mask is set, those
cells will be treated as if they were NULL.  It was more important
when GRASS didn't have a true concept of NULL value, however, masks still
can be useful.

-- 
Eric G. Miller <egm2 at jps.net>