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Comment by TazeTSchnitzel | Hacker News Reader

> Second Life and Open Simulator use it for asset storage

JPEG2000 is such a cool choice for Second Life. The fact any truncation of a JPEG2000 bitstream is just a lower-resolution version of the image makes for convenient progressive enhancement when loading textures over the network, right?

(And Second Life even used JPEG2000 for geometry, sort-of. I guess with the advent of proper mesh support, that may be less common now though.)

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JPEG itself has that property - you can decode any JPEG at 1/8 the size pretty easily, and progressive scan JPEGs do what you want here.

Dedicated texture compression formats would also do this since they use mipmaps, but I don't know if you can stream those.

For JPEG, if image is encoded using resolution progression, then decoder can not decode using quality progression (where image quality improves with each new piece of the image) and vice versa. With JPEG 2000, the decoder can decide which progression it wishes to use at decode time - by resolution, by quality, by component, or by spatial region.

Anyway, progressive jpeg2000 decoding is more sophisticated than progressive jpeg

This is super interesting. Do you have any more details on the use of JPEG2000 for geometry? I would be curious to hear more.

Sculpted prim. The object was basically a mesh of triangles in a fixed configuration, but the coordinates of the individual vertices were derived from an image (compressed using lossless JPEG2000, as any compression artifacts, not to mention chroma subsampling, would cause really ugly distortion). This was a halfway point between allowing arbitrary meshes and only pre-made object geometries (but with skinnable textures).

http://wiki.secondlife.com/wiki/Sculpted_prim

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