On Tue, Jul 5, 2022 at 1:30 AM Javier Jimenez Shaw <j...@jimenezshaw.com> wrote:
> Hi > > Do you know if there is any performance comparison between gdal2tiles and > COG? > > To display our geotiffs we are currently running gdal2tiles and storing > the (gazillion) tiles in Amazon S3. Then a webpage with openlayers is > showing them in WebMercator. > We are considering moving to make a COG file with the option > TILING_SCHEME=GoogleMapsCompatible and use also openlayers to read it (from > the same S3 server). However, our first tests are not running very fast > displaying the map in the browser. > > I do not know if anybody else had studied it, and if there is any trick to > make it faster. > Are you rendering the images in OpenLayers? And are you using the new-ish GeoTiff format for the COGs? If so, I think the performance issue is that OpenLayers has to read a lot of index data from the COG before it can make a http range request. With tiles, the schema is already defined whereas with a COG the app has to query the COG to get the schema before it can request the portions that it needs. I found that after the initial requests were completed that performance was fairly comparable. > PS. I cannot use JPEG compression (with alpha) with openlayers, but that > is another problem... or maybe not. > One kludge/work-around is to use a vector layer as a mask, but this discussion probably doesn't belong on the GDAL list. > Thanks, > Javier. > .___ ._ ..._ .. . ._. .___ .. __ . _. . __.. ... .... ._ .__ > Entre dos pensamientos racionales > hay infinitos pensamientos irracionales. > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/gdal-dev > -- Richard W. Greenwood www.greenwoodmap.com
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