[gdal-dev] GDAL raster processing library?

[Even Rouault]

Le mardi 12 juillet 2016 16:39:34, James Ramm a écrit :
> Hi Even,
> 
> The difference I see with pixel functions is that, as far as I understand,
> the pixel function is applied per pixel, so there is no possibility of e.g.
> the pixel buffer when have the function apply to 'blocks'.
> I may be way off, but many of the algorithms we deal with require some kind
> of neighbourhood search - a polygonise algorithm or flow direction
> algorithm being good examples.
> I dont think VRT pixel functions allow this?

True, they don't. Although there's the KernelFilteredSource that is close

> 
> So in that sense I'd see a VRT being 'just' another potential input data
> source.
> 
> Perhaps VRT pixel functions could be expanded to also allow 'window'
> functions?

Would make sense

> 
> A downside is it requires creating a VRT even when you only want to apply a
> such a function to a single dataset. Small effort, but still a bit more
> than throwing in any GDALDataset to be processed.

You could have an helper function to create the VRT dataset from the input 
dataset, the processing function and its parameters. A bit similarly to what 
Julien is doing in 
https://github.com/OSGeo/gdal/pull/142/files#diff-0c9bf560508edf2453cd2f776d72f905R121

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