[GRASS5] NVIZ and raster masking

[Otto Dassau]

On Mon, 30 Aug 2004 10:12:24 +0200
Markus Neteler <neteler at itc.it> wrote:

> Hi,
> 
> I tried to use the masking option in NVIZ (5.7) but to
> no avail. In 5.0.x it was working, maybe some recent
> updates to either ogsf or NVIZ have disabled this
> functionality?
> 
> Panel -> Surface -> Surface attribute -> Mask
> 
> As far as I recall, a 1/NoData map could be used
> to mask out subregions of a map.
> 
> Are there any tricks in that?

Hi,

according to this, I have another 2 question:
 
1) In GRASS 5.3 and 5.0 there still exists the module r.mask. 

###
-> manual "r.mask": 
"If  a  category is not assigned category value "1" it will automatically be assigned the category value  "0"  in  the resulting  MASK  file.   Any cells falling in category "0" will fall outside the newly formed mask, and  their  presence  will  be  ignored by GRASS programs run later on, as long as the MASK file remains in place."
###

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 ? 

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 ...


  best wishes
   otto