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View Full Version : need advice in setting up a "jellyfish" shader


burntheskies
09-15-2012, 07:13 PM
http://creationwiki.org/pool/images/4/42/Wallpaper_1024x768_MoonJellyfish.jpg

Now there are some nuances to that picture. The shader reacts to light as well as to itself ( self luminance.

Can bioilluminescence be done for organic models in Vray?

My take on this-

-subsurface as a pass
-a foggy blurred glass+translucency shader in vray ( restricts to 1 bounce)
-Vray light material with a grayscale map
-material + falloffs to make an "xray effect"

Ive been tossing these things in my head for about a week now and how to comp them or just if it can even be done in a single pass. However, not entirely versed in how to do this.

Now this question is not wholly restricted to Vray of course, Mental ray comments are also welcome.

(yes maybe I should have waited for that last one to finish lol)

pap87
09-17-2012, 03:27 AM
This sounds like a fun challenge. My knowledge is only in mentalray so I'll be using mentalray terminology.

I reckon this could be done all in one pass by combining an sss via the additional colour slot of an mia material x.

Diffuse - probably 0
Reflectivity - quite low around .05-.1 very low glossiness.
Transparency - around 75-80% with low gloss refractions no higher than .5
SSS - fairly low with a combined luminance value of around 20-25% so as not to go into >100% combined value with everything else.

You could also plug in a map to the ambient colour of the sss to create the incandescent look.
It may even be possible to do without the sss altogether and just try to get the refractions to do the job with a tiny amount of diffuse.

Linear workflow is very important here of course and just as important good lighting.

burntheskies
09-17-2012, 04:15 PM
This sounds like a fun challenge. My knowledge is only in mentalray so I'll be using mentalray terminology.

I reckon this could be done all in one pass by combining an sss via the additional colour slot of an mia material x.

Diffuse - probably 0
Reflectivity - quite low around .05-.1 very low glossiness.
Transparency - around 75-80% with low gloss refractions no higher than .5
SSS - fairly low with a combined luminance value of around 20-25% so as not to go into >100% combined value with everything else.

You could also plug in a map to the ambient colour of the sss to create the incandescent look.
It may even be possible to do without the sss altogether and just try to get the refractions to do the job with a tiny amount of diffuse.

Linear workflow is very important here of course and just as important good lighting.

First off, thanks for your insight. Also thanks just in general for taking the time to look.

In regards to your response.

1. Agree with the diffuse component having a small but noticeable influence. Have been using blue ATM, with the glass settings.

Will try the Ambient > sss connection in MR to see what happens.

I have spent a few days trying multiple methods to get this to work.

Things that I've tried recently-

1. A glass shader (with blurred refl/refr ) with a custom light at the outer rim of the mesh. This could illuminate the interior and provide interesting internal refraction/reflections.

- Ill try not to get to in depth with vray-

2. A translucency effect with Vray's default shader options, ( seems to have some nice effects) Probably will replace with their version of SSS entirely. Also need to take some post considerations as well.

3. A fresnel falloff with a bright material which emits actual light (Vray light material)

The amount of options seems mind-boggling, all with different advantage/disadvantage.


Some findings and thoughts-

The actual model is of a blue moon jellyfish ( Aurelia Aurita)

As previously stated the jelly above water can be incredibly clear. Experimented with IOR of 1.0 to start with effects.

The effects could be "shellaced" or blended together. Just don't know about self illumination within a material with blend/composite properties.

Some parts of its body act as a glass whereas others do not ( which are self emitting and subsurfaced)

Also when using just a fresnel falloff with a solid color the material looks much like an xray ( which is good) however the glassy look is lost entirely)

Probably all of this could be done in post but I really wanted to get more out of how some of this stuff works.

I will try to see what I can get in MR next.

burntheskies
09-17-2012, 04:42 PM
Some threads I found with similar issues that might help on the topic, or just in general

http://forums.cgsociety.org/showthread.php?t=802677 ( translucent leaves in MR)

http://forums.cgsociety.org/showthread.php?p=5062378#post5062378 (Incredible Hulk)

Also what would be the equiv to mia-material-x in max? I know thats the maya shader, and mental ray works "somewhat" the same in 3d packages.

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