[rudihammad]

Hello
I was wondering if there are any tricks to render SSS without much noise. I am using a small resolution (720x405) and only one computer (macbook pro).I am guessing that SSS is one of the hardest materials to render, but since I am using a small resolution, I don´t know, maybe there are some trick to render faster. I checked my units (cm) and density by default.
So, any tricks for a fair render in 5 minutes max?

Cheers

[eric nixon]

Depends which kind of material you want to make, mix the materials transparency with sss off and diffuse low, to make sure everything else is ok... later when the sss is working you can use the floor preview to adjust the specular highlights on their own.

SSS's can be quick just because they use very little sss, but I think what you want is a lot of sss, rendering quickly, in which case you need to use realistic settings, and its annoyingly sensitive

Try to use realistic attenuation. Like 0.4mm for fairly solid things like plastic.
Try to spread the load around the two colour chips (trans and scatter) to avoid any high values above 245 (max limit but it depends on which colour) if you get bright saturated noise reduce saturation, probably in the scatter chip but it depends.
If you see grey noise then increase scatter saturation, if you see dark noise esp with blue hues that also can be cured... but I cant remember right now

Also it can help to use different hues in each chip, I prefer a warmer tone in the trans chip.

Experiment with roughness set to 50.. roughness over 90 gets tricky.

Basically its not easy, the quickest sss is when it has real-world values but those numbers are rarely available, so the noise you see is quite informative (when your near to the right values)

This kind of pure plastic with almost no R0/R90 diffuse is always going to be slow though, this took over 1hr.


Plastic is the worst case scenario - very high density and very high saturation with rough transmission, its unlike most materials which also reflect diffuse light... Some sss will render in 5 mins.

[eric nixon]

Ok..., here is special '6min' pure trans plastic. - kind of cheating by using 0 roughness..

[hatts]

Eric, that's a lot of good information, thanks for contributing
Especially this bit, a very sensible workflow:

mix the materials transparency with sss off and diffuse low, to make sure everything else is ok... later when the sss is working you can use the floor preview to adjust the specular highlights on their own.

[zdeno]

Ok..., here is special '6min' pure trans plastic. - kind of cheating by using 0 roughness..

I don't like you of course , but have to admit Your materials are very convincing. Looks almost like sss plastic/rubber

I tested similiar approach few years ago in this thread

http://maxwellrender.com/forum/viewtopi ... 4&start=45

but didn't so succesfull as Your

[Bubbaloo]

I don't like you of course

[eric nixon]

Here's a quicker one, I recomend this formula wholeheartedly.. dear internet

30 mins.. sl18


EDIT: Actually the roughness 0 thing seems to give a speed boost only at lower SL, (so could be beneficial for animations) but seems to converge slightly slower for higher SL (Stills)

I am now finding that for soft plastics and darker tones of plastic, roughness 88 is working well, its also more logical, please look at the screenshot.... well I hope it looks more logical to anyone familiar with mxed.
I popped in to the 'pound-store' and had a close look at some cheapo soft plastic, it had a floral patterned surface like an etched stencil, I'm sure everyones seen this before... anyway i had a good look, and thought about what it was as a substance, rather than what it looks like from any particular angle/lighting... and came home and made this;



Both bsdf's have exactly the same subsurface settings, and trans colour, same ND, same attenuation, basically there the same apart from the surface properties. One has a fine normal noise map to roughen the coating creating the etched look, and the other is normal gloss, the weightmap is full 'stencil' i.e. B+W so maxwell isnt calculating both bsdf for any place on the surface, this prob helps with speed, as I didnt see any hit for using two bsdf's here.. enuff typing... enjoy

[rudihammad]

hi,
thanks for the replies. Very interesting to see how to work around that.
Well, I am also a renderman user, and I have been working with both renderers to take the best of each.
Here is a SSS test I did with renderman in a character I am modeling.



It is really fast.1min 12 for SSS and displacement too (and of course no noise at all).You can see behind the ear the SSS in red,and a bit on the nose. I don´t think I can get that with maxwell. Of course, I am talking about rendering with one computer.
So, I guess I´ll use maxwell for rendering the backround scenes maybe, and renderman for animated character.

Cheers

[eric nixon]

Lets keep this on a maxwellian note, sl14 (so 5 min sss with the disp turned off), basically I mean its fairly quick



If you cant tell what its supposed to be you need to fix your monitor, esp you Zdeno

BTW I no longer recommend roughness 0 except in some situations, it goes through the first Sl's quick but then hits some kind of wall, I used roughness 7 for this pink thing, but really most roughnesses work well, its flexible, above 50 it starts to affect the shading + intensity, so best only for darker tones.. could say more but its a long subject... above 90-93 is rarely good, like I mentioned before.

Here is a normal opaque plastic for comparison, (96.5 rough) which is good enough for backgorund objects and animations, this is sl21 it rendered for over an hour with disp;

[eric nixon]

Some variations. Same material with mapped diffuse and highly saturated mapped trans, the scattering is mid grey so that its neutral and doesnt pollute the trans colours. Mapping the trans works well here because the attenuation is small 0.6mm, Oh and displacement of course.



Hatts, what do you think? plasticky enuff?

another map.. makes it look more like dyed white glue.

[hatts]

Actually your "squares" map is starting to veer slightly into ceramic-looking, to me. Maybe an overly aggressive coating? Swishy waxy looking example is pretty great; reminds me of plastic toys made of cheapo color mixed materials.

Fantastic previous examples, this will be my new standard consumer plastic material. Had I known SSS was possible with that speed I would've started integrating it into my more conventional materials (like plastic), rather than reserving it for special uses.

Also "I don't like you of course" is now officially my favorite intro

[eric nixon]

Yes it does look like ceramic, esp in that context/form, I think its the hdri gamma (I dont trust it) thats pushing the ceramic look, but if you see the backlit squares, then you know its not a ceramic. Ofcourse were not looking at the same monitor which creates some room for error.

here are simballs, so its more familiar,





Yeah its a great intro...

Technically these aren't plastics anymore because of the grey sss as mentioned before, they are a workaround which works with short saturated transmission. Alternatively if you use weightmaps to define blocks of sss, (this is more applicable to longer transmission substances) so as to define different blocks of colour there is an issue. We cant map volumes, all mapping is 2d projection, so be careful with mapping those weightmaps.
If the maps are high contrast you can only get away with blocks of opposing colour like red and green which wont interact while scattering. For colours which mix, like red with blue, a gradual transition weightmap is needed. Again alll this only applies to weightmapped areas of sss bsdf's, because the mapping of the volume is somewhat bogus - just depends on the shape, no problem mapping slabs or spherical shells...

[rudihammad]

Hey Eric, really great information and materiales there.
I downloaded the pastel pink shader you put and tried it on the skin of a character.I tried to play around with the properties to
see if I could get a fake SSS but I couldn´t get a nice result.
Have you ever tried the material on a character? So far all the materials are applied to primitive object, and they look awesome. it would be nice to see a test on a head.
Here is a free obj head if someone wants to do test. by the way,I imported the obj and it is too small, so you´ll have to scale it if your units are set to cm in your software
http://www.ten24.info/index.php/shop/3d ... -model-52/
Cheers

[sandykoufax]

very nice materials, eric!

[hatts]

rudihammad, skin SSS remains a continuing challenge. If you peek around the forums you see people have made stabs at it but I don't think there's a usable solution yet, at least not compared to a C4D/other skin shader.