That is true to some degree, but with Terracotta we allow the frontend to do manipulations on the fly. Like changing contrast, applying colormaps, or band math. So the number of possible tiles is infinite.

If you don’t need that, you can just pre-generate all PNGs - then you don’t even need a server anymore, just a hash function to identify the right file and a big disk.

> like changing contrast, applying colormaps, or band math

Surely these are examples of things that a client could do with raster data independent of the capabilities of a server?

Only if the client has access to the full bit depth. The rendered PNGs are uint8, but the underlying raw data is often stored in 16 or even 32 bit precision.

I imagine that with HTTP range requests, it shouldn't be hard to access original TIFF data. Javascript or WebAssembly can then work with arbitrary bytevectors.

Yes, it’s possible. There are some proofs of concept for that IIRC. If you prefer to write everything in Javascript you can do that and do all heavy lifting in the client (plus some extra work to provide indexing and metadata like Terracotta).