[Qgis-developer] Raster Meeting Tomorrow - some UML

[Tim Sutton]

Hi Again

Oops I forgot the url for the rfc:

http://wiki.qgis.org/qgiswiki/RasterRefactorRfc

Tim

2007/6/20, Tim Sutton <tim at linfiniti.com>:
> Hi Martin (and others interested in raster)
>
> General:
>
> I made an RFC page for the work we are planning since I think it falls
> into the category of 'major overhaul' and would be good to have a
> formalised work specification. (Marco I took the liberty of tweaking
> your rfc template a little - hope thats ok!). The rfc includes an
> updated UML (created before I read Martins comments below) and the
> ArgoUml sources for the UML.
>
> Martin:
>
> Good comments! Yes chaining of filters was something I had in mind.
> Which also gets me to thinking the stretch operations could jjust be
> implemented as a kind of filter. The transparency too, though we would
> need to ensure that they were run in the proper place in any filter
> chain. We also need to evaluate how much filter type stuff we need
> since if we go ahead and eventually incorporate OSSIM functionality
> into QGIS we get a lot of image processing bundled in. I guess the
> same goes with grass raster processing facilities. Its something to
> think about anyway. Martin could you tweak the UML to include your
> ideas? I need to reread your ideas below a few times to properly
> digest what you are suggesting. Will be great if you can attend the
> meeting to discuss further...
>
> Regards
>
> Tim
>
> 2007/6/20, Martin Dobias <wonder.sk at gmail.com>:
> > Hi all,
> >
> > finally I took a look at the UML and also some materials about the
> > raster algebra / analysis. I've got some thoughts about that, some
> > might be worth considering:
> >
> > - raster function interface - in my understanding, renderer (filter),
> > transparency filter, strecher are essentially functions doing
> > operations on raster data matrices. Does it make sense to create a
> > common interface for them and then create a chain of these functions
> > that will give input for a pixel shader? In this case any custom
> > raster functions could be added to arbitrary places in the chain.
> >
> > - introduce one more abstraction: let's call it "raster data set" and
> > put it between raster layer and raster provider. How should that work:
> > Provider takes care of data acquiring from a specific backend. Data
> > set is the place where the main processing takes place. Raster layer
> > just accesses data set and draws it with its pixel shader. I see the
> > benefits in possibility to share data sets between layers, simpler
> > implementation of raster algebra, possibility to do some caching
> > already on data set level and more... (Well, a nice UML diagram would
> > describe the situation better)
> > btw. I'd like to use this approach also for vector data where all
> > vector editing / indexing / caching etc. would be done in vector data
> > set class - vector layer would only access data set for drawing and
> > maybe some more operations.
> >
> > - raster algebra with two or more layers (data sets) - are we going to
> > support this?
> >
> > - projections - are we going to support them?
> >
> > - usage of properties for data providers - this is just a technical
> > thing - I think it would be good to use a mechanism of properties,
> > e.g.:
> >   void setProperty(QString name, QVariant value)
> >   QVariant property(QString name)
> > This means that provider-specific stuff could be set/get with an
> > unified interface, so we could avoid having e.g. setProxy() function
> > in QgsRasterLayer as we do have now just because WMS provider needs
> > it.
> >
> > I don't know much about the rasters so excuse me in case I'm totally off :-)
> >
> > Cheers,
> > Martin
> >
>
>
> --
> Tim Sutton
> QGIS Project Steering Committee Member - Release  Manager
> Visit http://qgis.org for a great open source GIS
> openModeller Desktop Developer
> Visit http://openModeller.sf.net for a great open source ecological
> niche modelling tool
> Home Page: http://tim.linfiniti.com
> Skype: timlinux
> Irc: timlinux on #qgis at freenode.net
>


-- 
Tim Sutton
QGIS Project Steering Committee Member - Release  Manager
Visit http://qgis.org for a great open source GIS
openModeller Desktop Developer
Visit http://openModeller.sf.net for a great open source ecological
niche modelling tool
Home Page: http://tim.linfiniti.com
Skype: timlinux
Irc: timlinux on #qgis at freenode.net