CoolColJ's test pics thread

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CoolColJ
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Re: CoolColJ's test pics thread

Post by CoolColJ » Mon May 24, 2010 4:43 pm

Getting closer

I keep the same smooth Perlin noise combo, but using mulitplication of the 2 layers and then mulitpled this combo with another layer of noise, but using FBM, which has a rougher look to add some chaos. And I stretched the noise to give it a more wave like appearance.

Perlin noise(layer1 300% x layer2 675%) x (FBM noise with dimensions 100x200%) =
Water_noise.JPG
and the result underwater with 5% total noise output to water mesh displacement
im1274673540.JPG
100 samples

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Re: CoolColJ's test pics thread

Post by OnoSendai » Mon May 24, 2010 4:48 pm

Getting some pretty nice caustics there!

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CoolColJ
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Re: CoolColJ's test pics thread

Post by CoolColJ » Mon May 24, 2010 11:22 pm

Works pretty well above the water as well :)

At 1250 samples, but again the underwater cube doesn't seem to be lighting up. I guess all those irregular surfaces really disrupt Bidirectional MLT. I found Bidirectional path tracing better at forming the light on the underwater cube which is a surprise to me .... but BPT fails at all the other caustics
im1274675463.JPG
I'll put it up on the material database once I feel it's ready

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CoolColJ
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Re: CoolColJ's test pics thread

Post by CoolColJ » Tue May 25, 2010 12:26 am

Ok I figured out the issue of Indigo rendering indirectly seen caustics really slow. It doesn't have anything to do with the Pool model, or bump map on water or pool surface (up to a certain point anyway). It's because of the texture for colour itself it seems! This might explain why I thought Indigo rendered that water caustic test scene under articifial lighting so much faster than under the sun - no textures...
http://www.indigorenderer.com/forum/vie ... 063#p97063

I set the water mesh noise displacement at 3% for a calmer look. I put a checker tile pattern texture at the bottom of the pool, still a flat diffuse surface, and bam all of a sudden the caustics render considerable slower. They seem to render 1 checker square at a time....

How can this be?!

30 mins each
with texture - funny thing is, with the texture, Indigo's samples per second are higher! So that means the MLT isn't working as hard?
im1274696698.JPG
Texture for colour, no bump map
without texture - samples per second drops, but the caustics appear faster, maybe indicating MLT is working better...
im1274698741.JPG
no texture
No texturing, but with the tile bump mapping the bottom, 0.003, not much slower, but a whole lot faster than with the colour texture!!
im1274700617.JPG
just bump map

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dakiru
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Re: CoolColJ's test pics thread

Post by dakiru » Tue May 25, 2010 12:42 am

Ahh, I am enjoying this thread! :) Nice tests.

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Re: CoolColJ's test pics thread

Post by Zom-B » Tue May 25, 2010 4:03 am

very interesting ColJ find about caustics + texture!

I would suggest you have a final test with diffuse color vs texture with same color.
Should in theory look both the same, but regarding your find, texture should render caustics way slower!
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CoolColJ
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Re: CoolColJ's test pics thread

Post by CoolColJ » Tue May 25, 2010 11:06 am

Zom-B wrote:very interesting ColJ find about caustics + texture!

I would suggest you have a final test with diffuse color vs texture with same color.
Should in theory look both the same, but regarding your find, texture should render caustics way slower!
Might have something to do with the colour values themselves.
Like I mentioned, with the tile pattern texture, Indigo's MLT renders one square at a time

I'm trying out some tests with -
texture - white and 50% grey, white and that dark blue, all white and no texture to compare

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CoolColJ
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Re: CoolColJ's test pics thread

Post by CoolColJ » Tue May 25, 2010 12:47 pm

Ok it has nothing to do with textures - but the colour values themselves!

MLT engine needs to be adjusted.
Basicly MLT is completely attracted to bright surfaces. It just doesn't work on dark colours at all!

The more dark colours you have in the scene, the less MLT works, and so the higher the samples per second, becoming more like path tracing....

I placed a texture at the bottom of the pool with various colours - all rendered for the same time
Black, highest SPP, but zero caustics...
50% blue, small amount caustics
80% white, lowest SPP, but plenty of caustics
CCJ_Caustics on colours.JPG
Just to prove it - I place a black/white tile texture pattern on floor. Only the caustics on the white areas :)
Also made the cubes white, and that helped them to light up a bit
im1274745040.JPG
Even when directly seen - still no caustics on the black squares... Bidirectional path tracing had the same problem too.
im1274747130.JPG

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Godzilla
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Re: CoolColJ's test pics thread

Post by Godzilla » Tue May 25, 2010 1:22 pm

I don't know if you've tried this yet, but perhaps you could use a dark gray shade instead of pure black?
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Re: CoolColJ's test pics thread

Post by Borgleader » Tue May 25, 2010 1:40 pm

Godzilla wrote:I don't know if you've tried this yet, but perhaps you could use a dark gray shade instead of pure black?
Yes that would probably help, pure black like pure white does cause issues. Afaik pure black == complete absorption and so it would be normal not to see any caustics on the black squares.
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Re: CoolColJ's test pics thread

Post by StompinTom » Tue May 25, 2010 1:50 pm

If the black is 100% black, then it makes sense that all light that hits it will be absorbed, hence no caustics at all. I think it's a very similar issue as the 100% white issue, where you rarely have a 0% reflecting object, therefore even apparent black surfaces may actually be just a very very dark grey.

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CoolColJ
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Re: CoolColJ's test pics thread

Post by CoolColJ » Tue May 25, 2010 6:14 pm

Yeah I tried a dark grey of RGB 25,25,25, and while you can see some caustics, directly anyway I haven't tried it from above the water, it still looks a bit funny. I know in real life, caustics on black is just as bright as caustics on white

I still find it odd that 50% grey takes longer to find caustics than 80% white! Why should it really matter?
I know, traditionally, MLT does tend to love bright areas, but a caustic on a grey is still bright.
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Re: CoolColJ's test pics thread

Post by ENSLAVER » Tue May 25, 2010 7:30 pm

I think it's looking great. Through on black, no diffuse light reflects, no matter how much you shine on it. You may get some caustics coming back off it if it is reflective enough. At 25,25,25 you can see them pretty well, specially if you up the exposure. Perfectly black items rarely exist in real life, though they are easy to create on a computer.

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Re: CoolColJ's test pics thread

Post by zeitmeister » Tue May 25, 2010 8:11 pm

Guys, really nice tests and gorgeous bumpmap!

Just returned from 1 week holiday in turkey, and I miss that pool water that much!!! :roll: :D
Cheers, David



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Re: CoolColJ's test pics thread

Post by Pibuz » Tue May 25, 2010 8:13 pm

zeitmeister wrote: Just returned from 1 week holiday in turkey, and I miss that pool water that much!!! :roll: :D
...you bast*rd... :!:
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