Merging multiple raster pmtiles files into one

[BathyMapsAustralia]

Hey PMTiles Commune!

I've built a workflow for building tile packages for large areas of Australia. Due to the high resolution nature of the raster data I have been working with. I've had to split up the data into 1 degree x 1 degree regions otherwise the geotiff inputs were getting too large to handle efficiently. The result is hundreds of individual mbtiles and pmtiles files. These are good for my offline app as they can be selected for download but for displaying in my MapLibre web map, it is becoming inefficient due to the addition of so many individual pmtiles sources to the map. I'd like to combines the tile files into one master file for the webmap to make requests but I'm struggling to find a tool for merging either the mbtiles or pmtiles files. Most of the tools like tile-join are for vector sources. I generally use python-based tools for my tiling pipelines. Any ideas from the brains trust??? Thanks in advance. Thomas - BathyMaps Australia

[larsmaxfield]

Have you considered merging the original images?

#403 was a request regarding merging. I suggested they use libvips to join their TIFFs, generate a tileset, then generate a PMTiles from that:

...

• libvips with arrayjoin to merge the TIFFs, then with dzsave format=google to create a zyx tileset directory
• pmtiles with disk_to_pmtiles to convert that zyx directory to PMTiles

libvips works as a pipeline. It's very quick and does not require keeping images in memory when manipulating them. There's also a pyvips binding. I use that.

But perhaps that's not feasible?

As for your exact question, I'll leave that for others — I don't know.

[BathyMapsAustralia]

G'day @larsmaxfield thanks for the response mate, I'll check out Libvips to check feasibility. It would be easier to merge the tiles packages as they are much smaller in size than the original geotiffs. Thanks for the suggestion though, I will check it out 👍

[bdon]

You should build a VRT from the 1x1 degree regions and then build a single PMTiles archive from that mosaic. It would avoid most of the edge cases from attempting to merge archives after they are already tiled.

[BathyMapsAustralia]

@bdon Thanks for the inspiration, I may have actually found a way to parallel merge my cloud optimised geotiffs, which could be a feasible option!