[QGIS-Developer] webp for qgis server ?

[Matthias Kuhn]

Thanks for the excellent questions Even

Lucie has done the analysis and has all the parameters. She is not in 
the office these days. Once she is back I hope she can share the 
parameters and potentially also add a couple of additional rows to the 
table with improved parameters.

Sorry that I can't help more right now.

Matthias

On 6/9/20 1:56 PM, Even Rouault wrote:
>
> Matthias,
>
> thanks for the analysis. There are however a few unexpected results.
>
> 1) I'd expect gpkg pyramid_JPEG and COG_JPEG to have very similar 
> sizes, even COG_JPEG being potentially slightly smaller.
>
> And I'd also expect COG_JPEG to be slighly faster (but with less 
> confidence that my statement about size)
>
> Has by chance the source raster an alpha band ? In which case 
> gpkg_pyramid_JPEG would have dropped it, whereas COG_JPEG will encode 
> it as DEFLATE compressed mask, but still the difference is surprising
>
> Another explanation might be the block size. GPKG defaults to 256x256 
> tiles, whereas COG_JPEG to 512x512. Perhaps that affect compression 
> efficiency. And performance? (depends if your bench maintains the GDAL 
> raster opened between requests or not)
>
> If you didn't specify quality settings, both COG_JPEG and GPKG JPEG 
> should use the same quality of 75%
>
> 2) For the same compression type, block sizes and number of overviews, 
> MBTiles (the report doesn't specify the compression scheme for it) and 
> GeoPacakge should also have similar sizes and performance. They are 
> really close brothers, with just a few systems tables different.
>
> Even
>
> > Hi all,
>
> >
>
> > At OPENGIS.ch we have recently looked into different raster formats. The
>
> > results can be read here:
>
> > 
> https://www.opengis.ch/2020/06/09/offline-wms-benchmarking-raster-formats-fo
>
> > r-qfield/
>
> >
>
> > Not that surprising, but one of the interesting findings was that webp
>
> > is very efficient. Low filesize, reasonable rendering performance,
>
> > support for transparency. In short, it has all the potential for being
>
> > used as default transport format for WM(T)S.
>
> >
>
> > Looking at our server implementation, this format is not supported. Did
>
> > someone ever think about or even look into that?
>
> >
>
> > Regards
>
> -- 
>
> Spatialys - Geospatial professional services
>
> http://www.spatialys.com
>
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