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On 06/17/2010 12:36 PM, Jenny Turner wrote:
<blockquote
cite="mid:AANLkTimnNJyiizPdKrreYelGqph-wfwJ48B1Vk5K39gc@mail.gmail.com"
type="cite">Thanks Micha for your help but I got an error while doing
this
<div><br>
</div>
<div>1- Create new empty vectorial</div>
<div>2- run v.db.addtable command that you kindly sent me</div>
<div>3- use v.digit as defined previously</div>
<div>4- Inside tcltk's digitizing menu select Digitize new Centroid</div>
<div>5- Leave layer as 1</div>
<div>6- Change Mode to Manual Entry</div>
<div>7- First digitize boundary (by selecting boundary) by selecting
points with left-mouse-button and close polygon with right-mouse-button</div>
<div>8- A panel with "FORM" title appears with a tab saying
Attributes saying: "New record was created" saying CAT : 1 (this cat
refers to the land cover category right?); train_lbl value and GRASSRGB;</div>
<div>9- I place the values (water,1) for train_lbl and GRASSRGB</div>
<div>10- a box ask me for "ASSUME DATA ENCODING AS" a list appears. I
should select which one? ASCII? </div>
<div>11- In trhis case I select ASCII and press SUBMIT. In the bottom
of that box "Record successfully updated" appeared.</div>
<div>12- Insert centroid-1 and press submit in "Form" panel</div>
<div>13- Did the same for a few more polygons of cat 1</div>
<div>14- Did the same for a few more polygons of cat 2 and 3</div>
<div>15- Pressed Save and Exit</div>
<div><br>
</div>
<div>Then I realized that at my v.digit panel command output I had
this warning in there:</div>
<div>
<div><b>Could not set Tcl system encoding to 'ascii' (unknown
encoding "ascii")</b></div>
<div><b>Unable to read vector map</b></div>
</div>
<div><br>
</div>
<div>Questions:</div>
<div>1- Is this the right procedure?</div>
</blockquote>
Yes. I'd just add one thing that might make the work easier. You don't
need to enter the label and GRASSRGB for each centroid. Just leave them
blank. Then, when you're all finished digitizing, you can run an update
such as:<br>
echo 'UPDATE vector06 SET train_lbl="Forest" WHERE cat=1' | db.execute<br>
echo 'UPDATE vector06 SET GRASSRGB="0:255:0" WHERE cat=1' | db.execute<br>
(The second line will set the GRASSRGB column to green )<br>
<br>
<blockquote
cite="mid:AANLkTimnNJyiizPdKrreYelGqph-wfwJ48B1Vk5K39gc@mail.gmail.com"
type="cite">
<div>2- What encoding should I use?</div>
</blockquote>
Perhaps try Latin1<br>
<blockquote
cite="mid:AANLkTimnNJyiizPdKrreYelGqph-wfwJ48B1Vk5K39gc@mail.gmail.com"
type="cite">
<div>3- Regarding GRASSRGB field, what information usually you place
in there? Color code or color description?</div>
</blockquote>
The format is a text string containing three numbers <=255 separated
by ':'. So i.e. "128:128:128" is medium gray. <br>
<blockquote
cite="mid:AANLkTimnNJyiizPdKrreYelGqph-wfwJ48B1Vk5K39gc@mail.gmail.com"
type="cite">
<div>4- For Supervised classification algorithms in GRASS, Vector
type (accessible by using Query raster/vector tool) should be Boundary?
Because, for instance, if I press a defined boundary, in some places I
get Type: AREA and in others: Boundary (as shown bellow)</div>
</blockquote>
AFAIK, each of the classification algorithms needs a *raster* map of
training areas. So your next step, after finishing the vector map of
training areas, will be to convert it to raster. So you'll be doing
something like:<br>
v.to.rast vector06 out=train06 use=cat type=area<br>
Now the cat value that will be used for each raster pixels inside a
vector area is the cat value of the *centroid*. Again, the boundary in
GRASS's topological vector structure is not relevant to the enclosed
area's attributes. You can, if you want, give the boundary the same
cat value, and same GRASSRGB as the centroid. Then, if you use this
column to color the vector when displaying the map, the boundary and
the filled area will be in the same color. But for classification, when
you convert the vector training areas to raster, what will be used is
the *centroid* cat value.<br>
<br>
<blockquote
cite="mid:AANLkTimnNJyiizPdKrreYelGqph-wfwJ48B1Vk5K39gc@mail.gmail.com"
type="cite">
<div>
<div>(...)</div>
<div>Map: vector06 </div>
<div>Mapset: landsat</div>
<div>Type: Boundary</div>
<div>Id: 9</div>
<div>Layer: 1</div>
<div>Category: 3</div>
<div>Driver: dbf</div>
<div>Database: C:\GRASS6\grassdata/North-Carolina/landsat/dbf/</div>
<div>Table: vector06</div>
<div>Key column: cat</div>
<div>cat : 3</div>
<div>train_lbl : urban</div>
<div>GRASSRGB : 3</div>
<div>(Thu Jun 17 10:34:04 2010) Command finished (0 sec)
</div>
<div>(Thu Jun 17 10:34:06 2010)
</div>
<div>v.what --q -a map=vector06@landsat
east_north=639279.744997,227730.071998 </div>
<div>(...)</div>
<div>Map: vector06 </div>
<div>Mapset: landsat</div>
<div>Type: Area</div>
<div>Sq Meters: 2158429.741</div>
<div>Hectares: 215.843</div>
<div>Acres: 533.360</div>
<div>Sq Miles: 0.8334</div>
<div>Layer: 1</div>
<div>Category: 3</div>
<div>Driver: dbf</div>
<div>Database: C:\GRASS6\grassdata/North-Carolina/landsat/dbf/</div>
<div>Table: vector06</div>
<div>Key column: cat</div>
<div>cat : 3</div>
<div>train_lbl : urban</div>
<div>GRASSRGB : 3</div>
</div>
<div><br>
</div>
<div>Thanks for your help and support</div>
<div><br>
</div>
<div>Jenny</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div>
<div>
<div>
<div class="gmail_quote">On Wed, Jun 16, 2010 at 7:59 PM, Micha
Silver <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:micha@arava.co.il">micha@arava.co.il</a>></span> wrote:<br>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000">
<div class="im">On 06/16/2010 06:55 PM, Jenny Turner wrote:
<blockquote type="cite">Hi Micha and GRASS-users/list
<div><br>
</div>
<div>Let me see if I get this straight</div>
<div>1- use v.digit (e.g. <span lang="PT"><span><span
style="font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span></span><span
lang="PT">v.digit -n map=vector00 bgcmd=d.rast map=lsat5_1987_40 )</span></div>
<div><span lang="PT">2- Inside tcltk's digitizing menu select
Digitize new Centroid</span></div>
<div><span lang="PT">3- Leave layer as 1?</span></div>
<div>4- Change Mode to Manual Entry?</div>
</blockquote>
</div>
All the above looks good.
<div class="im"><br>
<blockquote type="cite">
<div>5- And for each Centroid I select a Cat right?</div>
</blockquote>
</div>
Yes, always using the *same* cat for training areas of the same type. <br>
<div class="im">
<blockquote type="cite">
<div>(Is this the proceeding?)</div>
<div><br>
</div>
<div>About this, I have two questions:</div>
<div>a- I have to leave "Insert New record into table" checked
right?</div>
</blockquote>
</div>
Yes
<div class="im"><br>
<blockquote type="cite">
<div>b- After I left "Insert New record into table" checked,
Layer 1
and Cat 1 and Mode: Manual Entry, when I presss in the image a Error
Window appeared stating: Database table for this layer is not defined.
Where shall i define the database table for a new vectorial that I
digitizing?</div>
</blockquote>
</div>
Ah, v.db.addtable vector00 col="train_lbl varchar(16), GRASSRGB
varchar(16)"<br>
THis should setup an attrib table with two columns, one for a label and
one for an RGB color for the training area.
<div class="im"><br>
<blockquote type="cite">
<div>c- When I press the image a point is created but how can I
define the boundaries of the centroid?</div>
</blockquote>
</div>
First digitize the boundary. Here you need not enter any attributes.
The cat values are also not relevant.<br>
NExt digitize a centroid inside each boundary. Give each centroid a cat
value that matches the type of training area. So all the forests will
be i.e cat=1, and all the urban will be i.e cat=10, etc.
<div>
<div class="h5"><br>
<br>
<blockquote type="cite">
<div><br>
</div>
<div>Thanks</div>
<div>Jenny</div>
<div><br>
<br>
<div class="gmail_quote">On Wed, Jun 9, 2010 at 7:06 PM, Micha
Silver <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:micha@arava.co.il" target="_blank">micha@arava.co.il</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div text="#000000" bgcolor="#ffffff">
<div>
<div>
<blockquote type="cite">
<div><font face="monospace">polygon to a certain category? <br>
</font></div>
</blockquote>
</div>
</div>
<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>
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<pre cols="72"><font face="monospace">--
Micha Silver
Arava Development Co. +972-52-3665918
<a moz-do-not-send="true" href="http://www.surfaces.co.il"
target="_blank">http://www.surfaces.co.il</a>
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<pre cols="72"><div><div class="h5">--
Micha Silver
Arava Development Co. +972-52-3665918
</div></div><a moz-do-not-send="true" href="http://surfaces.co.il"
target="_blank">http://surfaces.co.il</a>
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<pre class="moz-signature" cols="72">--
Micha Silver
Arava Development Co. +972-52-3665918
<a class="moz-txt-link-freetext" href="http://surfaces.co.il">http://surfaces.co.il</a>
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