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?
Thanks
Markus
On Mon, 30 Aug 2004 10:12:24 +0200
Markus Neteler <neteler@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
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!
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. 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.
Paul
On Mon, 30 Aug 2004 20:02:46 +0100 (BST)
Paul Kelly <paul-grass@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
Otto