Marbles and solid glass objects

[TheGreenGiant]

? you should post ref pics of real objects you want to have the render look like. I have no idea what you meant. ?

[Per-Anders]

if you're getting problems with a bubble look, then use a decal shader and make sure the backside has no specular (or even diffuse) don't forget to add in a good fresnel to make the internal relfections work well (as well as external).

[greek_fire]

depending on how your object is lit, you may need to take transluscence into account. if your using raytracing, be sure to attend to the raytrace options on yer shader

[trthing]

I have some doubts here too:

I guess he is referring to: how do we tell Maya that the sphere we just built is a "soap bubble" not a solid glass ball (marble)? I am almost sure it defaults to the last case (at least the caustics tell me so). What if we want to realistically model a paper weight with some bubbles inside?

[DesignDawg]

I may be a little off here, but I'll give a stab at it:

Actually, Maya treats a closed sphere as a solid object. I have a feeling you are not raytracing, or at least you haven't set up refractions.

Look through the manual about how to set up refractive index and turn on raytracing.

Ricky

[chillfillan]

Sorry about the confusion, but yes pretty much what I meant was-- does Maya treat a sphere as a solid object or a shell? So I would just use a normal glass shader, but set it up correctly
Thanks

[trthing]

@DesignDawg

OK, raytrace, allright... but imagine you want to model a solid glass ball with some air bubbles inside, and how do you model a soap bubble with another soap bubble inside (same wireframe appearance, sphere inside sphere, but different physical situations, glass-air versus thinsoap-air-thinsoap-air)?

[mark_wilkins]

Here's how it works:

When a ray intersects your sphere object, it changes angle because of the difference in refractive index, then travels in a straight line. When that ray exits the sphere, it changes angle again as a result of going from the higher refractive index to the lower.

That's exactly what happens in the real world with light passing through a solid sphere of glass, so you get a similar look.

To create a thin-walled bubble of glass, you need to make two concentric spheres, very close to each other, and invert the normals of the inner sphere so that they point inward.

To create a small bubble in a sphere of glass, do the same thing but make the inner sphere small.

-- Mark

[augustus]

Maya has suface thickness attribute for this. If you leave surface thickness at 0, Maya treats a closed object as a solid object. Giving a small surface thickness will give you what you want. Result will close to the result of mark_wilkins's method, but not same (Actually, the difference is big. Just try and see what i mean)

[trthing]

How's your book going?

@ augustus & Mark:
Yes, I thought of the second method (the thickness attribute) for soap bubble like objects and the first one for thicker glass bulbs (e.g. light bulbs). But I never got confirmation about zero thickness equals solid object.

Thanks for your response!

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.