[Qgis-developer] Data exchange between QGIS and SAGA [was: QGIS Processing Framework]

[Camilo Polymeris]

Hello saga developers,

in case you haven't followed the development of the QGIS Processing
Framework and SAGA interface, a short introduction:

I was selected to implement a QGIS to SAGA interface in context of
Google's Summer of Code 2011 program. The last weeks have been spent
designing and implementing basic parts of a more general framework to
processing modules. There is interest in interfacing at least SAGA,
the Orfeo Toolbox and OSSIM to QGIS. A rough design document can be
found at [1]. Note that the implementation[2, 3] differs
substantially, though.

One of the most important and difficult remaining parts is data
exchange (raster & vector). I have been studying SAGA's API [4], but
am not sure how to handle it & would appreciate comment from people
more familiar with it.

Do you think it would be easier (or cleaner) to interface SAGA's
relevant data structures to QGIS' dataproviders or layer structures?
For comparison, see the QGIS API docs.[5]

>>> - I/O : how will this be handled ? I'm asking this related to the recent
>>> mails with interest for providing ossim image chains in Qgis.
>>> If it must support module chaining, then there is a need for an
>>> abstraction
>>> of the i/o mechanism. is it the qgis dataproviders ? a module can take a
>>> raster/vector dataprovider as input and can output a raster/vector
>>> dataprovider ?
>>
>> Yes, qgis dataproviders, I think. Perhaps alternatives later. This is,
>> IMO, one of the most dificult aspects remaining to define.
>
> I'd love to hear some thoughts from the Qgis gurus about this.
>

Any thoughts or comments welcome.

Regards,

Camilo

[1] https://github.com/polymeris/qgis/wiki/QGIS-Processing-Framework
[2] https://github.com/polymeris/qgis/tree/master/python/processing
[3] https://github.com/polymeris/qgis/tree/master/python/plugins/saga
[4] http://www.saga-gis.org/saga_api_doc/html/annotated.html
[5] http://doc.qgis.org/head/index.html