[GRASS-user] Assess land cover change

Greetings
I have 2 land cover maps (1990 and 1995) and I want to detect changes between them and create a change detection matrix. can this be done in GRASS?
Regards,
Luis Lisboa

On 17/10/12 15:46, Luis Lisboa wrote:

Greetings
I have 2 land cover maps (1990 and 1995) and I want to detect changes
between them and create a change detection matrix. can this be done in
GRASS?

r.report and r.stats can be used to cross-tabulate two or more raster maps.

r.report output is easier to read on-screen, but r.stats output is easier to post-process.

Moritz

Thank you Moritz
Just one last question: is it possible to produce a raster product that attributes a code/color to a specific land cover change?
Regards
Luis

On Wed, Oct 17, 2012 at 3:25 PM, Moritz Lennert <mlennert@club.worldonline.be> wrote:

On 17/10/12 15:46, Luis Lisboa wrote:

Greetings
I have 2 land cover maps (1990 and 1995) and I want to detect changes
between them and create a change detection matrix. can this be done in
GRASS?

r.report and r.stats can be used to cross-tabulate two or more raster maps.

r.report output is easier to read on-screen, but r.stats output is easier to post-process.

Moritz

On 17/10/12 16:28, Luis Lisboa wrote:

Thank you Moritz
Just one last question: is it possible to produce a raster product that
attributes a code/color to a specific land cover change?

One way I can think of immediately would be to code the land covers of the two dates in different order of magnitudes and then sum the two, i.e.

year t:
100 forest
200 built-up
300 agriculture

year t+n

1 forst
2 built-up
3 agriculture

year t + yeart+n (you can do that with r.mapcalc):

101 : forest that remains forest
102 : forest that has become built-up land
301 : agricultural land that has become forest

etc

But, as always, there are probably many other ways :-).

Moritz