Is this after reading the 3DXtract article ? I cannot download the issue right now, but there is an article about faking SSS. The one on the right looks best imho.

I looked at the article. But I couldn't see much of a difference in the pictures. I'm modeling a person and thought I should start working on a texture for the skin. I would like to find a setting (if possible) so that there is a change in the object's texture color when it is placed directly between a light source and a camera lens. I'm playing with the DCG and Shoestring plugins to see which ones approach this.

mmmh, it looks like that you've used only fake fresnel, sincerely i don't see any translucent effect... But we can discuss more about it, it's a nice challenge:-) -TOXE

I'm trying to get the look of what a flashlight does when a hand is placed over the light. Or a bat's wing in front of a light.

I know subsurface scattering. The issue is the even fake fresnel doesn't give the control of where the transparency is that is needed. Hope CS5 gives us subsurface scattering. Brian

Attached Link: http://www.renderosity.com/messages.ez?ForumID=12400&Form.ShowMessage=2206573

This really is interesting. I just purchased Cinema 4D R9 XL this evening!

I agree with Brian, with Fake fresnel is impossible to control the zone where we need a translucent effect, maybe is possible to do it decently with fake fresnel and a custom mapped object. I hope too to see SSS in C5, but sincerely i really hope that Eovia will consider the integration of some external render like Mental ray or Maxwellrender. At this point (for my professional works), Carrara render have too much limits. -TOXE

Anyway. The one on the left was done with the Iridescent function and the one on the right was done with the Fresnel function (it lights the whole perimeter). Both are from the Shoestring Shaders plugin and were used in the transparency settings of the objects. I will try ShadersPlus from Digital Carver's Guild next.

Message edited on: 04/12/2005 03:16

The difficult part of translucency is determining where the object is thick vs thin- the shaders just don't have that kind of info available to them. SSS suffers from a similar issue- when a shader is called, it is called for a single point. You have no access to the points around you (to determine if they should be scattering light into your point). I'm playing with stuff to try and address some of these issues, as is Eric- see his message about the edge shaders which could help control translucency- if you have both, combine it with Lit. markd

Toxe, apart from no SSS, which limits do you have trouble with?

Indirect light is the best way to produce realistic images, but for now is too much slow and it don't work very well in my opinion, too much artifacts. No blurry transparencies and the blurry reflection are incredibly slow too. Every reflective surface in nature have a little blur. Also, it's difficult to create realistic glass in carrara compared to other softwares. The last, the caustics, that are not precise enough for my taste. We'll see, unfortunately some of my clients aren't blind and i really need to be competitive on the market. This is the hard world of job:-( -TOXE

A technique I learned from my Strata days was that for area lighting, if you aim a spot light at a plane and turn up its brightness quite high, you get a decent area light. Carrara seems to be much happier with this then using the Glow channel to create an object light source. I get much less artifacting and faster renders that way. I find the renderer quite fast, and I am on an old machine so I am not sure exactly what you are rendering. I do find glass slow to render. Mabey once the new forum is up that I hear rumoured they should create a rendering section, so that we can all discuss rendering techniques and get the best out of the engine. The Strata community made great progress under after discussing things amongst each other. As for mental ray, XSI is tempting me! but I think I will hold off for now.

Two cubes? When I have the time I have an idea I'd like the to try. Brian

Actually now that I look at it, it looks like it might be shader plus. Brian

The problem with successively smaller objects, like in the case that Shonner has done, is that Carrara is a limited ray depth of 25'ish. I say ish as I've tried this with one of my images and I had less because Carrara would stop after a certain point. Probably due to some tolerance on transparency. This sort of limits how 'translucent' you can get. Make the steps to the smaller objects too much and it'll be noticeable. Make it too small and there won't be much depth to the translucency. Also it can be really hard to make sub surfaces if they aren't simple like a cube or sphere. Another draw back is that if you look close (or if there is something behind the object) you'll see through to what's behind the 'flesh'. Not really want you want but not much to get around it. However if Carrara did allow for a significant increase in ray depth, super fluffy clouds could be made but that's a different issue.

It's a flesh colored cube inside a slightly transparent flesh colored cube. Just playing around. It only works (if you can call it that) if global illumination is turned on and the light is behind the object. If the light is in front then the outer transparent layer ruins any illusion.

Message edited on: 05/02/2005 16:37

There are really two effects you are trying to achieve:

1. scattered light transmission (like red hand over a flashlight - the light passes through the volume and is scattered, attenuated by depth and coloured by the material
2. backscatter (like the glow you see looking at something front lit) where light penetrates a volume and is scattered back along the light path or at an angle to it.

In reality they are the same phenomenom the difference being the angle between the scattered light and the light source (in 1, the angle is > 90 degrees and in 2 it is < 90 degrees).

both attributes are needed to fake translucent materials like skin. The curve filter with iridescence technique can be used to control the intensity of glow or transparency of a surface at changing angles to a light and so it can fake some of both effects as any organic object tends to become thinner (smaller crossectional area) towards an edge. Fake or real fresnel can help make the effect more realisticby attenuating effects away from edges. That being said, it is all still based on the angle of a surface to a light and not actually based on determining a volume and so it breaks down in places. You could try using a UV-mapped texture map to define what parts of a model are "thin" or not instead of frake fresnel to attenuate the light effect (the map is black aside from fingers, ears, nostrils etc).

I think it is going to require a new renderer or at least a new lighting model to get a good SSS effect.

Message edited on: 06/16/2005 03:36

Beautiful isn't it?! It's a nice addition to C5Pro. For those with C4Pro, I've still been experimenting with the fake effect and a better effect is to use the iridescence shader and curve editor to add some red to the diffuse colour of the surface at the perpendicular to the light source and blue when it is in line with the light source. But C5Pro's SSS shading really does the job well though.