[TZGISUG] Raster analysis in QGIS

[Steve Ball]

Hi Pekka,

Thx for the advice. I downloaded QGIS2.2 on the OSGeo4W method that 
weekend, and it crashed. However, I did manage to get what I needed 
doing urgently using a combination of QGIS 1.8 and ArcMap. For the 
longer term we will see whether we can get QGIS 2.2 to work and handle 
everything.

cheers, Steve

On 21-02-2014 10:34, Pekka Hurskainen wrote:
> Hi,
> 
> Yes its not really the right forum - you should repost it to QGIS-User
> list. However, I strongly suggest updating to QGIS 2, it handles
> raster much better, and the Sextante plugin is now integrated to the
> core QGIS - it's now simply called "Processing". If you're under
> Windows, I recommend installing it through OSGeo4W installer, in that
> way it's easy even to install other necessary software like Saga,
> Grass, Orfeo Toolbox. Together all these will make your QGIS much more
> powerful than alone, and best of all, you can use all of them straight
> from QGIS Processing toolbox.
> 
> What you refer as stratifying - have you tried the raster calculator ?
> There is one in QGIS, but much better ones in Saga and Grass.
> 
>  Btw. QGIS 2.2 is scheduled to be released today, anxiously waiting
> for that!
> 
> Pekka
> 
> On Thu, Feb 20, 2014 at 6:55 PM, Steve Ball
> <steve.ball at mpingoconservation.org> wrote:
> 
>> Howdy folks,
>> 
>> Not sure this group is the best forum to ask this question, but I
>> thought I'd give it a go. I have a raster of biomass values (derived
>> from RADAR data, the values are in floating point format if that
>> matters). I need to stratify that into 5t/ha bands, i.e. where the
>> value ranges from 0 to 5, then 5 to 10 etc. Displaying the raster
>> visually in these terms is easy enough, but actually converting the
>> data into this form appears much harder. Then I would like to be
>> able to check the distribution of vector point data across those
>> strata (ought to be straightforward), and also to compute the total
>> area of each such stratum (not yet sure how I do this). It would be
>> nice, not least for future replicability, to accomplish this all in
>> QGIS without resorting to ArcView.
>> 
>> Any pointers on relevant instructions on the interwebs most
>> appreciated, since am struggling to guess the appropriate search
>> terms. Can the Sextante plugin help?
>> 
>> cheers, Steve
>> 
>> ps. Am currently using QGIS 1.8 but could switch to 2.0.1 if that
>> would do the trick.
>> ________________________________________________
>> Steve Ball
>> Chief Technical Adviser
>> Mpingo Conservation & Development Initiative
>> www.mpingoconservation.org [1]   
>> 
>> _______________________________________
>> TZGISUG mailing list TZGISUG at lists.habari.co.tz
>> List Info: http://mail.habari.co.tz/mailman/listinfo/tzgisug [2]
>> Web Site: http://www.tzgisug.org [3]
>> Facebook: https://www.facebook.com/tzgisug [4]