Irradiance ?

[sidandmj]

Is it any good?

I put this together after seeing a similar rendering on 3dtotal.com.

It took about 1.5-2days to model and find textures and render.

still needs some work but i thought i would share it for feedback.

I used one key light and 3 area lights

64 Irradiance samples and a read/write cache

the final render took 3.5 hrs to render on an athlon64 3200 with 1gig of ram

I am attatching the hip file for your enjoyment.

there is a GI Otl emedded in the hip file. i have learned a couple more things about GI in mantra since i created it, so there are a couple of changes to make. for photons and irradiance only, everything is used as is on the otl. if you wish to render "final gather", using photons to help the irradiance cache, just set the photon shader to use full irradiance, and the output driver to use the cache. please note that the irradiance cache option on the otl is not fully implented, as there were problems with the read/write options in the past.

hope you all like

[sidandmj]

hmmm the hip file didnt get attatched on the previos post so here it is?

diner1.zip

[Lukich]

Looks very nice and cozy. I'd prefer it to my working place I especially like the Houdini logo on the table...

[Jason]

very nice image - i like it a lot. be nice to get some closeups of the elements.

how did you find the usability of the cache?

[sidandmj]

i found that the cache works very well, easy to use.

i first started the cache before i had any textures on, and added one light at a time. i found that rendering it

small and uprezing was no problem, as long as the default error on the ROP was set to 0. if i then use read/write option i can continue to write into the cache.

i re-rendered this with the read only option and .1 error and shaved about an hour off the render times.

with that in mind i would assume that the cache is written to until the SCENE lighting is established,

then it is used as a read only from then out as characters, objects, lights, change in the scene. when using read only it is possible to multi-proc the render, and thats how a render can benefit from the cache.

i could probably optimize it a little more as i am using raytraced shadows on the area lights. if i were to generate a global photon pass with the area lights i could use the global map instead of using the area lights, and calculating rt shadows, which should significantly speed up the enitre render . . . .

thats the hope anyway, will post results as they are available . . .

i can attatch the textures i used if anyone wants them, just reply . . .

thanks for the comments, ideas, questions, and suggestions, keepem comin . . .

[lisux]

Thanks sidandmj.

The problems i 've had with the cache are related to possibly a bug in Houdini. When i use the $JOB variable in the cache file path, it isn't writed.

If i use an absolute path there isn't any problems.

I've a doubte, if i doesn't specify a cache file, the cahce is done in memory?

So you use read/write mode until you finish the shading & lighting phase, in order to improve your cache data, and when you have finished it you use read only.

If the objects are animated i think that a sequence of cache files are needed, maybe a first render in low rez to generate a sequence of caches, and then the high rez render using the generated caches could be the right way?

[sidandmj]

i dont think one would want many cache files, especially refined ones, as they can be quite large. i expect rather that one cache file with the "scene" lighting baked into it is sufficient for the read only portion.

rendering from different points of view into the same cache file with a zero error will fill in missing areas from the cache.

once the scene has been rendered from every key view, i can think of no reason to continue writing to the cache.

if a character walks into the room, only that characters irradiance would need be different from the calculated cache therefore requiring calculation, but again i dont think it is appropriate to write that information into the cache.

since read only cache files can be used during multi-proc rendering i think that once the scene cache is complete, throw as many procs as you can at each frame. With enough procs, rendertimes could drop to minutes per frame instead of hours . . . . which is what it would take if you had to write 100 cache files to render a 100 frame animation . . .

i am rendering a camera move on this sequence to test the single cache theory . . . so far results have been promissing. . . but i have not added a char or other objects to the scene

[Jason]

Hey again,

Wondering if you tried out the point-cloud style Global Illumination shader found in the pcpack?