[GRASS-user] Using Tck/tk vector digitizer for training areas

[Jenny Turner]

Thanks Micha for your help but I got an error while doing this

1- Create new empty vectorial
2- run v.db.addtable command that you kindly sent me
3- use v.digit as defined previously
4- Inside tcltk's digitizing menu select Digitize new Centroid
5- Leave layer as 1
6- Change Mode to Manual Entry
7- First digitize boundary (by selecting boundary) by selecting points with
left-mouse-button and close polygon with right-mouse-button
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;
9- I place the values (water,1) for train_lbl and GRASSRGB
10- a box ask me for "ASSUME DATA ENCODING AS" a list appears. I should
select which one? ASCII?
11- In trhis case I select ASCII and press SUBMIT. In the bottom of that box
"Record successfully updated" appeared.
12- Insert centroid-1  and press submit in "Form" panel
13- Did the same for a few more polygons of cat 1
14- Did the same for a few more polygons of cat 2 and 3
15- Pressed Save and Exit

Then I realized that at my v.digit panel command output I had this warning
in there:
*Could not set Tcl system encoding to 'ascii' (unknown encoding "ascii")*
*Unable to read vector map*

Questions:
1- Is this the right procedure?
2- What encoding should I use?
3- Regarding GRASSRGB field, what information usually you place in there?
Color code or color description?
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)
(...)
Map: vector06
Mapset: landsat
Type: Boundary
Id: 9
Layer: 1
Category: 3
Driver: dbf
Database: C:\GRASS6\grassdata/North-Carolina/landsat/dbf/
Table: vector06
Key column: cat
cat : 3
train_lbl : urban
GRASSRGB : 3
(Thu Jun 17 10:34:04 2010) Command finished (0 sec)

(Thu Jun 17 10:34:06 2010)

v.what --q -a map=vector06 at landsat east_north=639279.744997,227730.071998
(...)
Map: vector06
Mapset: landsat
Type: Area
Sq Meters: 2158429.741
Hectares: 215.843
Acres: 533.360
Sq Miles: 0.8334
Layer: 1
Category: 3
Driver: dbf
Database: C:\GRASS6\grassdata/North-Carolina/landsat/dbf/
Table: vector06
Key column: cat
cat : 3
train_lbl : urban
GRASSRGB : 3

Thanks for your help and support

Jenny



On Wed, Jun 16, 2010 at 7:59 PM, Micha Silver <micha at arava.co.il> wrote:

>  On 06/16/2010 06:55 PM, Jenny Turner wrote:
>
> Hi Micha and GRASS-users/list
>
>  Let me see if I get this straight
> 1- use v.digit (e.g.  v.digit -n map=vector00 bgcmd=d.rast
> map=lsat5_1987_40 )
> 2- Inside tcltk's digitizing menu select Digitize new Centroid
> 3- Leave layer as 1?
> 4- Change Mode to Manual Entry?
>
> All the above looks good.
>
>  5- And for each Centroid I select a Cat right?
>
> Yes, always using the *same* cat for training areas of the same type.
>
> (Is this the proceeding?)
>
>  About this, I have two questions:
> a- I have to leave "Insert New record into table" checked right?
>
> Yes
>
>  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?
>
> Ah, v.db.addtable vector00 col="train_lbl varchar(16), GRASSRGB
> varchar(16)"
> THis should setup an attrib table with two columns, one for a label and one
> for an RGB color for the training area.
>
>  c- When I press the image a point is created but how can I define the
> boundaries of the centroid?
>
> First digitize the boundary. Here you need not enter any attributes. The
> cat values are also not relevant.
> 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.
>
>
>
>  Thanks
> Jenny
>
>
> On Wed, Jun 9, 2010 at 7:06 PM, Micha Silver <micha at arava.co.il> wrote:
>
>>   polygon to a certain category?
>>
>>  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:
>> train_area        cat
>> ------------------------
>> forest             1
>> agriculture        2
>> urban              9
>> water             10
>> ....
>>
>> 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).
>>
>> When you're done digitizing training areas, you might add another column
>> or two to the attrib table for the training areas -
>> v.db.addcol train_areas col="train_label varchar(16), RGBCOLOR
>> varchar(16)"
>> then give each centroid cat value a suitable label and an RGB color combo,
>> etc.  Makes life easier down the line...
>>
>>
>> This mail was received via Mail-SeCure System.
>>
>>
>> _______________________________________________
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>>
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>>
>>
>>
>>
>>
>>  --
>> Micha Silver
>> Arava Development Co. +972-52-3665918http://www.surfaces.co.il
>>
>>
>
> This mail was received via Mail-SeCure System.
>
>
>
> --
> Micha Silver
> Arava Development Co. +972-52-3665918
> http://surfaces.co.il
>
>
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