[GRASS-user] Howto: Vector Digitizer in GRASS64 Linux

GRASS GRASS user
1

Greetings

Before I do some “practical” questions I have one “big question”, why when I do v.digit a Tcl/Tk digitizer appears instead of the Wxpython digitizer? I’m running it in Linux with a recent grass64svn version?

Now, since I’m using tcl/tk I have some practical questions regarding digitalization. My objective is to create training areas for classification. I didn’t find any tutorial regarding of how to use vector digitizer to create training areas. I suppose that I need to create polygons and then add “centroids”. Right?
1- First I draw a boundary and close it. In v.digit toolbox I have selected “Insert new record”, in layer 1 and Category 3 and Mode “Next not used”
When I do “Close line (right mouse button) I get an error window stating: DAtabase table for this layer is not defined”. And the same happens for each and every boundary that I define Uhm… WHat am I missing? I mean, what step should I do before?
Thank you

Best regards,
Pedro

2

Hi,

2010/4/15 Pedro Roma <pedroroma1982@gmail.com>:

Before I do some "practical" questions I have one "big question", why when I
do v.digit a Tcl/Tk digitizer appears instead of the Wxpython digitizer? I'm
running it in Linux with a recent grass64svn version?

Not sure if I understand well the question. Tcl/tk v.digit is
available from wxGUI layer manager menu because wxGUI digitizer still
doesn't work on MS Windows and has some other problems. Anyway wxGUI
digitizer starts from map display menu or popup menu "Start editing".

Martin

--
Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa

3

Greetings

Before I do some “practical” questions I have one “big question”, why when I do v.digit a Tcl/Tk digitizer appears instead of the Wxpython digitizer? I’m running it in Linux with a recent grass64svn version?

As Martin said, use the wxPython digitizer from the Map display window.

Now, since I’m using tcl/tk I have some practical questions regarding digitalization. My objective is to create training areas for classification. I didn’t find any tutorial regarding of how to use vector digitizer to create training areas. I suppose that I need to create polygons and then add “centroids”. Right?
1- First I draw a boundary and close it. In v.digit toolbox I have selected “Insert new record”, in layer 1 and Category 3 and Mode “Next not used”
When I do “Close line (right mouse button) I get an error window stating: DAtabase table for this layer is not defined”. And the same happens for each and every boundary that I define Uhm… WHat am I missing? I mean, what step should I do before?

You just need to add a database table to the new vector layer. You probably want this anyway in order to set a class for each digitized area.
I the GUI, from the menu “Database->Manage databases->New table”. Then in the v.db.addtable window, select which vector, and go to the Options tab to type in which columns and attribute types you want. At minimum you’ll probably want a string column for the class name, and maybe an integer column for a “class_id”
.

··· 
-- 
Micha Silver
[http://www.surfaces.co.il/](http://www.surfaces.co.il/)
Arava Development Co.  +972-52-3665918