[GRASS5] NVIZ and raster masking

Otto Dassau otto.dassau at gmx.de
Tue Aug 31 03:43:06 EDT 2004

On Mon, 30 Aug 2004 20:02:46 +0100 (BST)
Paul Kelly <paul-grass at stjohnspoint.co.uk> wrote:

> On Mon, 30 Aug 2004, Otto Dassau wrote:
> > It creates masks with values 1 or 0 and works fine with modules like d.rast or r.mapcalc. Does this have changed? I realized that r.mask doesn't exist in GRASS 5.7 anymore, and using a 1/NoData map as Markus describes also works. What would be the correct way to mask subregions?
> >
> > 1/NULL or 1/0 ?
> Null or 0 cells are masked. Cells that contain *any* other value 
> (including 1) are not masked. It is really very versatile!

This means I don't need to create an extra 1/NULL or 1/0 map as long as I make sure, that only masked areas contain NULL or 0 values? 

> >
> > 2) In this context I found out that i.smap doesn't support any of those MASKs described above. I always need to add a second step with r.mapcalc to calculate a masked version of the resulting map. But this is maybe sth. for the bugtracker ...
> >
> Yes that is a known bug that i.smap does not support MASKed or null cells. 
> It really should be documented in the manpage if it is not already. 
It is not documented yet. Yes it would be helpfull, I guess.

> There 
> are comments in the source code that suggest it does but it is not 
> implemented correctly and would require quite a lot of work to get it 
> fixed up IIRC.

thanks a lot

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