[GRASS-user] Long post - Remote Sensing - Classifications

[Moritz Lennert]

On 18/02/09 17:17, mitch_TX wrote:
> Hi community,
> 
> This semester I'm teaching an Intro Remote Sensing course using commercial
> softwares. Since I'm a free spirit, my goal at the end of the semester is to
> show the students that everything could be done using GRASS rather than
> Envi,Erdas or Idrisi.
> Given the fact that they are familiar with GUIs, I'd like to use “graphical”
> commands as much as possible (I don't want to scare them)
> 
> I have a few questions:
> 
> How do I actually save a color composite image as a raster? I know how to
> create it and visualize it
> (GUI: Add RGB or HIS layer → I choose the bands → Display active layer on
> the Map Display)
> (Command: d.rgb red=lsat5_1987_40 at landsat green=lsat5_1987_50 at landsat
> blue=lsat5_1987_30 at landsat -o)
> ...but I don't know how to save it, say, to use it as a base image to draw
> ground truth for a supervised classification.

r.composite
(Raster->Manage map colors->Create RGB)

> 
> 
> The other question is something that has been getting me crazy for a couple
> of days: classifications.

[...]

> Is this  a bug or am I “the bug” :-) ??
> I know that if the command line works, you all may not “see what the problem
> is”? But as I said I'd like to use the GUI.

There were issues in 6.3 with the GUI appending @MAPSET to names whereas 
the i.* commands couldn't deal with such names. This was corrected since 
(but probably after 6.3 came out). You might want to try with 6.4 (IIUC, 
there should be a Lenny package available in the gfoss.it repository soon).

> 
> 
> Let's try with the Supervised using the group and sub-group that worked
> before:
> (GUI: Imagery → Classify image → Interactive input for supervised
> classifications)
> 
> i.class window, say I want to use the NIR band to draw my truths:
> 
>  lsat5_1987_40
> (good)
> 
> group
> lsat_try (the group that worked before)
> (good) 
> 
> sub (if I type list to see the available sub-groups I get: no subgruop
> available in the current mapset)
> 
> the same happens if I create a group and sub in the user mapset using the
> copied images.
> 
> What am I doing wrong? :,(

Can't help you on this one, but maybe same issue of file naming ?

Moritz