[gdal-dev] Tiled GeoTiff that reduce the amount of reads in XYZ maps

[Even Rouault]

On mardi 3 juillet 2018 09:16:34 CEST Guy Doulberg wrote:
> Even suggestions worked for me,
> 
> I am working on code that can ease the process of doing that
> 
> https://github.com/satellogic/telluric/blob/get_tile_aligned/telluric/georas
> ter.py#L1344
> 
> I will update when it is done
> 
> After working with that I realized that now I have a new question. How
> deep(low) to go in alignments.
> 
> If I align the raster only in the zoom level the raster is at then I might
> fetch more then one tile of overviews image data when overviews are used,
> but to align the raster to zoom level that is very low doesn't make sense
> either since the headers will be huge.
> 
> How do you guys deal with this case?

There's no good way of solving this with a single GeoTIFF File. You would need 
each overview level to have possibly a different extent than the main overview 
level. While you could put several images in the same GeoTIFF file with each 
their GeoTIFF keys, that would no longer be overviews in the TIFF meaning (and 
there is no support in GDAL for that).

-- 
Spatialys - Geospatial professional services
http://www.spatialys.com