Hi
I,m a new user of GRASS,and I'd like to be able to compare maps (with
the same categorie values).Does anybody know how to do it?
I've got map of vegetation with ,for example 5 or 10 classes,and
I'd like to get the DIFFERENCE between those maps.It 's look
easy to combine or overlay map in Grass,but I just can't find
useful commands to make comparison...
Thanks .
There is many ways to do this, but my favorite program r.mapcalc could be
a good start.
echo "diff.map=if( map1 != map2)" | r.mapcalc
Then you could examine what values that have changed with r.stats
and count numbers of pixels at the same time.
r.stats -c input=diff.map,map1,map2
Lars
Lars Schylberg Email: larss@fmi.kth.se
Dept. of Geodesy and Photogrammetry
Royal Institute of Technology (KTH) Tel. +46 8 790 86 33
S-100 44 STOCKHOLM, SWEDEN Fax. +46 8 790 66 10
Hi
I,m a new user of GRASS,and I'd like to be able to compare maps (with
the same categorie values).Does anybody know how to do it?
I've got map of vegetation with ,for example 5 or 10 classes,and
I'd like to get the DIFFERENCE between those maps.It 's look
easy to combine or overlay map in Grass,but I just can't find
useful commands to make comparison...