[QGIS-Developer] webp for qgis server ?

[Even Rouault]

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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