[gdal-dev] How would I build a custom pyramid ?

[Alain Camus]

Hello list, 

I have a set of tiles at resolution 0.5 m/pxl. Based on this data, I'd like to create a pyramid that has zoom levels 0.166667, 0.333333, 0.666667 and 1.66667 (the data will only be viewed in geoserver at these levels, so I guess it will be faster if I prepare the data at these levels). 

I think gdal_retile only allows multiplying the zoom levels by 2. Thus I think I will need those steps : 


    1. gdal_translate to get the lowest zoom level (0.5 --> 0.166667) 
    2. gdal_retile to give these tiles the good size in pixels, mosaic them and to create the next two levels (0.333333 and 0.666667 ) 
    3. gdal_translate again to get the highest zoom level (1.66667 , which is not the double of the previous one) starting from the 0.666667 tiles . 
    4. gdal_retile again to give these tiles the good size in pixels and mosaic them 
    5. manually adapt the pyramid config files 

At 0.5 m/pxl, I have 8000 geotiffs each 4000 x 4000 pxls, so I think it'll take a lot of time, especially steps 1 and 2. 

Would you have an advice to speed up the process or decrease the number of steps ? 

Alain 




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