[Qgis-user] Vectorization and georrectify

[Alex Mandel]

On 06/02/2010 09:18 AM, nikos ves wrote:
> On Wed, 2010-06-02 at 17:08 +0100, Kim Besson wrote:
>> Hi 
>>
>> What I am refering is to creating polygons or points vector files
>> using a raster map as background, like creating training areas or so.
>> Do you understand? 
> 
> 
> Training areas, to my knowledge, are AOI's (usually polygons) that refer
> to the same attribute. If you need to make then, then you need to
> digitize them manually. There no software in the world that could make
> training areas for you! You train your computer to do the computation,
> not the other way around!
>  
> But, if you mean classification, i don't think qgis can do that. You
> need to use grass

Well what I mentioned before is the way to create a vector layer (you
can choose point, line or polygon). The most common term I know for this
is 'digitizing'.

So for you,
1. Load whatever raster background you want.
2. Create new layer - It's on the toolbar, with a big star usually
	It will prompt you to create attribute fields to store data.
3. Edit your layer, digitizing your polygons or points.
4. Save you edits and enter the attributes.
5. You are free to use the layer however you like, if you are trying to
use it as training data for classification you will need to import it
into a tool that does Image Classification like GRASS, R, SAGA(I think),
etc...

This is all well documented in the QGIS Manual.
http://www.qgis.org/en/documentation/manuals.html

Thanks,
Alex