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<font face="monospace">On 06/09/2010 07:48 PM, Jenny Turner wrote:</font>
<blockquote
cite="mid:AANLkTil6RP8Q9q-d045ew3NaSNTtji30K3Th3yj3BVqb@mail.gmail.com"
type="cite"><font face="monospace">Greetings</font>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">I'm using WinGRASS (from OSGEO4W
installer) to do some supervised classification. Since I'm using
winGRASS i.class function is not available neither wxGUI's vector
digitizer. So I'm using tcl/tk but I'm a bit confused on using it. </font></div>
<div><font face="monospace">About the background images I used a
discussion from last week regarding this but now.. How can I define a
category? I mean, How can atribute a polygon to a certain category? <br>
</font></div>
</blockquote>
<font face="monospace">This indeed is not obvious. What I've done is
change the category mode from "Next not used" to "Manual entry". This
is set in the lower part of the v.digit window (in tcltk interface).
Now each time you digitize a *centroid* for a training area, set its
cat value to some standard value you choose. For example, you might
decide:<br>
train_area cat<br>
------------------------<br>
forest 1<br>
agriculture 2<br>
urban 9<br>
water 10<br>
....<br>
<br>
Now for each training polygon which is a forest, set the cat value of
its centroid to 1, agri areas will get value 2, and so on for all the
centroids of all the training polygons. (Note that the cat values for
the boundary lines are pretty much irrelevant in GRASS's vector model).<br>
<br>
When you're done digitizing training areas, you might add another
column or two to the attrib table for the training areas - <br>
v.db.addcol train_areas col="train_label varchar(16), RGBCOLOR
varchar(16)"<br>
then give each centroid cat value a suitable label and an RGB color
combo, etc. Makes life easier down the line... <br>
<br>
</font>
<blockquote
cite="mid:AANLkTil6RP8Q9q-d045ew3NaSNTtji30K3Th3yj3BVqb@mail.gmail.com"
type="cite"><font face="monospace"><br>
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<font face="monospace"><br>
<br>
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<pre class="moz-signature" cols="72"><font face="monospace">--
Micha Silver
Arava Development Co. +972-52-3665918
<a class="moz-txt-link-freetext" href="http://www.surfaces.co.il">http://www.surfaces.co.il</a>
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