[QGIS-Developer] FFT convolution plugin help

[Luigi Pirelli]

I agree with uclaros, probably a processing model is what you are looking
for, if it fits your processing speed and complexity.... you can also
always convert your model in a python script and eventually add some high
level parallelization. BTW i.fft would be enough efficient and raster are
just linked in grass (automagically by grass provider in processing)
without need to import/export.

Bye form an ex Barrio de Sampedro citizen

cheers

Luigi Pirelli

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On Fri, 5 Feb 2021 at 17:58, salvador bara <salva.bara at gmail.com> wrote:

>
>
>     I'm new to the list, and I apologize in advance if this is not the
> proper place for this post. In that case any pointer about where to send
> this request would be highly appreciated.
>
>     I am working at Universidade de Santiago de Compostela, in
> mathematical methods for light pollution research. Some people asked us for
> an easy way to create light pollution maps using QGIS. These maps can be
> easily produced by 2-D FFT convolution of georeferenced nighttime satellite
> image rasters, using kernels of ~1Mpixel size defined by arbitrary
> functions (that is, not just Gaussian ; ) ). We routinely do so using
> Matlab, and we have checked that it can also be done using the QGIS menu
> after a rather lengthy set of inividual operations based on the i.fft and
> i.ifft grass routines. We are assessing the feasibility of writing a
> dedicated tutorial on that. However, for most users of QGIS in our field,
> this step-by-step algorithm turns out to be a rather cumbersome procedure.
>
>     I have to confess I have no programming skills (at all) for
> implementing an FFT conv pluging in QGIS. If anyone in the developer world
> would be interested in this issue and its potential applications, I would
> be happy of cooperating. I am sure there is a large user community that
> would take advantage of this feature. For more info about the underlying
> methods you may want to have a look to  https://arxiv.org/abs/1907.02891
>
>     All the best,
>     salva bará
>
> --
> Salva Bará
>
> Barrio de San Pedro, Compostela, GALIZA (European Union)
>
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