So I have hit a snag. I wish to merge multiple XYZ tile sets together. Meaning I have multiple directories which contain tiles in the format /zoom/x/y.png.
I tried just copy and pasting them in to the same directory, but it appears that some of the tiles have clashing file names, and thus I lose some tiles with this approach. For instance, nearly all the sets will have the tile 1/1/1.png, and this will be overwritten every time.
I am taking this route because the tiles are being generated from multiple VRTs that span a wide area, each with large swathes of NODATA between them. So when I end up tiling them, 90% of the tiles it generates are empty bogus. Normally this wouldn't be a big issue, but at the scale I am at it ends up adding many hours to the processing time.
One solution I think would be to convert all the tile sets to use a single origin, determined by analyzing the VRT sources for the different tilesets. Then I would go through all the tiles in each of the tilesets and convert their /zoom/x/y.png path to use the new, recalculated origin.
The main function for converting the tile would look something like this:
getTilesNewXYZPath(
originalTileOriginLat, # Original tile's origin latitude
originalTileOriginLon, # Original tile's origin longitude
originalTileX, # Original tile's x coord at zoom level z
originalTileY, # Original tile's y coord at zoom level z
originalTileZ, # Original tile's zoom level (z)
newTileOriginLat, # Origin latitude to convert to
newTileOriginLon, # Origin longitude to convert to
)
How would I do this? Does anybody have some math they could point me towards, besides that on the OSGeo wiki? Or am I going about this the whole wrong way, and need to use a different strategy? Or even worse, is the overwriting behavior I am experiencing not caused by gdal2tiles.py?
