[GRASS-user] Landcover change

GRASS GRASS user
1

Dear all,
I have two landcover change maps and I wanted to know if there is any functionality or module that allow us to compare the maps and landcovers? (e.g. class 1 2 and 3 in both maps and identify the pixels
(Map 1 Map 2)
1 | 1
1 | 2

1 | 3

2 | 1

2 | 2

2 | 3

3 | 1

3 | 2

3 | 3

Thank you
Regards,
Antonio

2

On Tuesday 22 of October 2013 08:33:41 Luisa Peña wrote:

Dear all,
I have two landcover change maps and I wanted to know if there is any
functionality or module that allow us to compare the maps and landcovers?
(e.g. class 1 2 and 3 in both maps and identify the pixels
(Map 1 Map 2)
1 | 1
1 | 2
1 | 3
2 | 1
2 | 2
2 | 3
3 | 1
3 | 2
3 | 3

Thank you
Regards,
Antonio

Have a look at r.cross.

Nikos

3

On 22/10/13 09:54, Nikos Alexandris wrote:

On Tuesday 22 of October 2013 08:33:41 Luisa Peña wrote:

Dear all,
I have two landcover change maps and I wanted to know if there is any
functionality or module that allow us to compare the maps and landcovers?
(e.g. class 1 2 and 3 in both maps and identify the pixels
(Map 1 Map 2)
1 | 1
1 | 2
1 | 3
2 | 1
2 | 2
2 | 3
3 | 1
3 | 2
3 | 3

Thank you
Regards,
Antonio

Have a look at r.cross.

Or at r.report or r.stats with the two maps as input.

Moritz

4

Antonio:

>> I have two landcover change maps and I wanted to know if there is any
>> functionality or module that allow us to compare the maps and landcovers?
>> (e.g. class 1 2 and 3 in both maps and identify the pixels
>> (Map 1 Map 2)
>> 1 | 1
>> 1 | 2
>> 1 | 3
>> 2 | 1
>> 2 | 2
>> 2 | 3
>> 3 | 1
>> 3 | 2
>> 3 | 3

Nikos:

> Have a look at r.cross.

Moritz Lennert wrote:

Or at r.report or r.stats with the two maps as input.

Multiple raster maps fed to r.report! Interesting. The output is quite large
here using two maps with (1 to) 28 or 30 classes each. I am not sure on how to
use this ouput yet. I guess it deserves a short explanation in the manual.

Thanks, Nikos

5

On 22/10/13 10:56, Nikos Alexandris wrote:

Antonio:

I have two landcover change maps and I wanted to know if there is any
functionality or module that allow us to compare the maps and landcovers?
(e.g. class 1 2 and 3 in both maps and identify the pixels
(Map 1 Map 2)
1 | 1
1 | 2
1 | 3
2 | 1
2 | 2
2 | 3
3 | 1
3 | 2
3 | 3

Nikos:

Have a look at r.cross.

Moritz Lennert wrote:

Or at r.report or r.stats with the two maps as input.

Multiple raster maps fed to r.report! Interesting. The output is quite large
here using two maps with (1 to) 28 or 30 classes each. I am not sure on how to
use this ouput yet. I guess it deserves a short explanation in the manual.

I think r.report output is only useful for few classes or if you are looking for a specific correspondence of classes. For more advanced treatment of such crossing of maps, I would use r.stats, saving the results into a file and then any spreadsheet or other tool of your choice to visualize or analyze the results.

Moritz

6

Luisa,

[Please keep discussions on the list]

On 06/11/13 13:15, Luisa Peña wrote:

Just one question:
I have used r.cross and it has produced a raster layer which allocates a
value (e.g. 1 to 1 | 1; value 2 to 1 | 4) but when I export it this ID
information will not be kept . Is there any solution to keep this
information there?

You've already asked the same question two years ago ;-):

http://lists.osgeo.org/pipermail/grass-user/2011-July/061271.html

I don't think the answer has fundamentally changed.

Moritz

7

Dear Morritz
Sorruy for sending the email to you and for not remembering this
…
Neverthless, if I open in other GIS software it will not automatically recognize the classes right?
Luisa

···

2013/11/6 Moritz Lennert <mlennert@club.worldonline.be>

Luisa,

[Please keep discussions on the list]

On 06/11/13 13:15, Luisa Peña wrote:

Just one question:
I have used r.cross and it has produced a raster layer which allocates a
value (e.g. 1 to 1 | 1; value 2 to 1 | 4) but when I export it this ID
information will not be kept . Is there any solution to keep this
information there?

You’ve already asked the same question two years ago ;-):

http://lists.osgeo.org/pipermail/grass-user/2011-July/061271.html

I don’t think the answer has fundamentally changed.

Moritz

8

On 06/11/13 16:25, Luisa Peña wrote:

Dear Morritz
Sorruy for sending the email to you and for not remembering this
  ..
Neverthless, if I open in other GIS software it will not automatically
recognize the classes right?

It will recognize the numeric classes, but not the text labels attached to the classes. You have to export those with r.category.

Moritz