Simple SSS not rendering

Discussions about rendering in SOFTIMAGE©
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Pancho
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Simple SSS not rendering

Post by Pancho » 05 Dec 2013, 16:41

No idea why this is so hard. In Modo SSS just renders super fast. But in MR?

I have a character with several Simple SSS materials. The SSS materials alone render super slow (eyes, tongue, etc.) but if I add the body/face around it (different group of polys) then it just not renders at all. Even preview never starts. Are there any unwritten rules or is simple SSS not the appropriate shader? The lightmaps have the size of the final image. No idea which size they have to be in general. This is so outdated...

Any ideas? How to achieve proper SSS in SI nowadays?!

Cheers

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gustavoeb
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Re: Simple SSS not rendering

Post by gustavoeb » 06 Dec 2013, 04:20

have you tried this?
http://www.si-community.com/community/v ... it=mr+sss2

legacy mr sss has some single threaded things, sss2 is suposed to be fully multi-threaded and its parameters make more sense to.
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Pancho
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Re: Simple SSS not rendering

Post by Pancho » 06 Dec 2013, 14:03

Thanks for the tip! Just wondering: What's the right way to add reflection or refraction to your SSS object? Again, in Modo all included in the very same shader. I added the reflection so far with a Mix_2_Colors (add mode) node and a phong or architectural shader. But I guess for refraction this won't work like it does with reflections.

So, how does one get reflections/refractions with the SSS shader?

Cheers!

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gustavoeb
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Re: Simple SSS not rendering

Post by gustavoeb » 06 Dec 2013, 14:42

Hey Pancho. Yes, mix node it is, BUT, not in add mode. Light either reflects, absorbs, scatters or refracts, so you really want to mix inbetween one or the other NOT ADDem together.
It will work for refraction or reflection.

(tip, there is a node called dieletric, which will let you do fresnel like coating based on ior values)

Here is a screengrab:
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sss.JPG
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gustavoeb
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Re: Simple SSS not rendering

Post by gustavoeb » 06 Dec 2013, 15:07

gizz, I had forgoten how much fun the rendertree is...

ps: apparently sss2 cant be plugged into shadows, now that is no fun :/
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Pancho
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Re: Simple SSS not rendering

Post by Pancho » 06 Dec 2013, 15:26

And Final Gather with Light maps is even less fun. : (

Simply not starting to render. WTF?! How is this supposed to work after all. Some kind of cheat like back in the 90s or early 2000?

It took the preview port 53s till it started to render. Only the skin shader!

123s in combination with the dielectric and architectural shader. And this is not the slowest computer.

So, this is really something from the past.

P.S.: In combination with an SSS shader I guess ADD might the correct way to combine both shaders. Imagine a something like a backlit ear. The reflections seen from the front don't weaken the light penetrating the ear from behind (e.g. like self illumination). Two different things!? In a diffuse lighting model you are right for sure.

Thanks for the examples!

Pancho
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Re: Simple SSS not rendering

Post by Pancho » 06 Dec 2013, 15:28

P.P.S.: Nice pearl effect.

P.P.P.S.: THe lightmap should have the same dimensions as the render format (in pixels), shouldn't it?!

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Mathaeus
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Re: Simple SSS not rendering

Post by Mathaeus » 06 Dec 2013, 16:46

Pancho wrote:P.P.S.: Nice pearl effect.

P.P.P.S.: THe lightmap should have the same dimensions as the render format (in pixels), shouldn't it?!
Could be smaller or larger, smaller gives more chance for flicker in sequence, or incorrect edges. Light map is "mapped" on screen, that's it.
If long time belongs to pre - computing phase, perhaps you can make it a lot faster by supplying something else as final gathering shader, using 'ray type' or another ray switcher.
Also, if you have this shader on polygon cluster, there's chance for multiple pre computing - so, if this is the case, I think it's good idea to avoid it on clusters.
Modo subsurface relies on ray-tracing, so it's simpler to use and more accurate. Misss_fast stuff is based on simpler, theoretically faster trick - diffuse shading is blurred between vertices, also there's comparison of front-back distance (relative to camera). In other words, you can't expect too much of misss_fast thing - and it definitively wants 'back surface' in order to work.

Pancho
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Re: Simple SSS not rendering

Post by Pancho » 06 Dec 2013, 16:59

Thanks! So is there anything more fancyful out there at the moment? The whole texturing part in SI looks damn ugly/old compared to the simplicity of Modo or Lightwaves nodal system. Wished they would clean it up to todays standards.

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mattmos
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Re: Simple SSS not rendering

Post by mattmos » 06 Dec 2013, 18:09

Arnold or VRay? ;)

I'd recommend you sign up for the redshift beta too, especially if you're looking for speed.

Kzin
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Re: Simple SSS not rendering

Post by Kzin » 06 Dec 2013, 19:05

Pancho wrote:
123s in combination with the dielectric and architectural shader. And this is not the slowest computer.

So, this is really something from the past.
its because the renderer calls light loops for every mat shader you use. the new shadersystem will change that for mr.

Pancho
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Re: Simple SSS not rendering

Post by Pancho » 06 Dec 2013, 21:10

Hi Matt,

I tried to use Vray. If you can remember the complicated texture set up of the ingots: Unfortunately this didn't work with Vray. Somehow the multiple UV regions were screwed up. Probably there are some custom Vray nodes, but the texture projection should work for all third party renderers. So it's been back to MR. Arnold. Mmmhh. A few more bucks and I'd go for it.

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Hirazi Blue
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Re: Simple SSS not rendering

Post by Hirazi Blue » 07 Dec 2013, 10:42

mattmos wrote:Arnold or VRay? ;)

I'd recommend you sign up for the redshift beta too, especially if you're looking for speed.
3delight maybe? :-s
Stay safe, sane & healthy!

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