tiled exr equivalent for 8 bit images?

[super gnu]

ive mentioned this before, but its a bit annoying that, as far as i know, the only option for tiled images (i.e. load on demand, multiple LOD stuff) is exr, which only supports 16 or 32 bit.


since the vast majority of textures are 8 bit, we cannot take advantage of the massive file handling and efficient memory usage of tiled images, without converting to exr, which converts the images to `16 bit, which uses loads more ram, totally negating any benefits.


any suggestions? is there a file format ive missed? chaos... wanna write a new file format for textures?


cheers!

[^Lele^]

EXRs are only 16 bit half, or 32bit full float per channel.
It'd have to be a hack, and use cleverly one 32 bit channel.
I can smell a number of issues doing that...

However, a file format specific to vray (vrimage would more than do, i reckon) with a number of sweet options (atlases, tiles, memory-mapped textures akin to the .mi format, arbitrary channel bitness, efficient per-tile and per-scanline compression, and so on) would have me jump in joy...

[henning]

Yes, this would be great. Maybe vrimage is already capable of supporting some of these things?

[vlado]

We were in fact, thinking of supporting 8-bit EXR files where one pixel is packed into a single 32-bit integer; there is no problem to implement tiled rendering in this way. Let me know if you want to experiment with this.

Best regards,
Vlado

[super gnu]

yes i would find this very useful to test. my last two jobs have used dozens of 8k x 8k textures to cover a big manually tiled landscape. being able to reduce the hackiness of this by using fewer, larger textures would be very useful. but would you think this would save ram over using jpegs in the scene?

[instinct]

If you save them as tiled EXRs, than it is possible to load only needed tiles. If all tiles are needed that will not change a thing (actually prolly creating a little bit of overhead i guess?). As the tiles can be loaded per bucket you can save quite some ram depending on what is visible in the current buckets. This comes at a speed penalty tho (similar to vrayproxies)

Regards,
Thorsten

[super gnu]

yes this is my understanding of tiled exr's too. however in the past when i have tried to use them in place of 8bit jpegs (by far the most common texture type, for me at least) the ram usage has actually gone up, due to everything being treated as 16 bit, or even 32 bit internally.

im happy to have a trade off with rendertime of course. being able to balance rendertime against ram usage is one of the nice things about vray and tiled exr for textures should be a nice tool in this regard.

[snivlem]

Can't tiffs do this?