[gdal-dev] How to merge tile trees

[Jukka Rahkonen]

Ari Jolma <ari.jolma <at> gmail.com> writes:

> 
> Dash,
> 
> I have only a limited experience with tiles and gdal2tiles, so I'm not 
> sure the correctness of this but anyway. I'd also like to see if I have 
> understood correctly, so please anybody correct if I'm wrong.
> 
> The tiles are in a two-level directory tree, where the top level has the 
> zoom level and the one below that has a number, which I assume is some 
> kind of global location reference. Within that there are the tiles, 
> which have a name, which, I assume, are some kind of global location 
> reference. For example I have this:

I assume that your assumption of global location reference is correct when
either "mercator" or "geodetic" profile is used. When profile is "raster"
then the tile grid is based on the extents of the source data and merging
directories from different rasters will not work. I fear that the result
will be bad also with the global grids because the border tiles tend to
contain  partially nodata and as a result there will be more or less wide
stripes of missing data at each zoom level at the outer borders of the added
data. 

-Jukka Rahkonen-