[gdal-dev] RV: question how to get spot and landsat share a common grid.

[Even Rouault]

Juan Carlos,

> 
> Here is our question: How should we generate the tiled pyramids of the 2,5
> mts SPOT images in a way that both images use the same grid without
> 'resampling' the whole landsat to 2,5mts, of course, hoping to make one web
> tile tree that goes down to 2.5 meters in some places, but only down to
> 15meters in other places. (as Frank Warmerdam clearly put out)

I don't think this is possible with a unmodified gdal2tiles (but I'm not a specialist of 
gdal2tiles, so I'd be happy to be corrected), at least not by having the 2.5 and 15m 
resolutions. The issue is that 15 / 2.5 = 6 which is not a power of 2, and as far as I know, 
gdal2tiles only knows to generate zoom levels that differ by power of twos.
A workaround would be to use a global tiling system like Google Maps, run gdal2tiles on your 
landsat and spot separately (which will cause resampling them to the closest pre-defined 
zoom level to their native resolution), and then copy the file tree structure of spot on top of 
landsat.

An enhanced gdal2tiles could possibly handle your case by generating a custom WMTS tiling 
scheme where you would define the zoom levels, but this has yet to be written.

Even


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