Prisms...

User avatar
VitalBodies
Technician
Technician
Posts: 329
Joined: Mon Feb 04, 2008 2:48 am
Contact:

Prisms...

Post by VitalBodies » Mon Mar 31, 2008 7:43 pm

I am trying to create a prism effect using a triangular prism.
I set the Index of refraction to a high grade of borosilicate optical glass.

I created a spline object that is a classic triangular prism.


I positioned a spot light set to white light and narrowed the beam and aimed the light near the top of prism.
I positioned a cube that is matte white wall material for the light to hit once it passes through the prism just to see if the light was being split into waves.

I basically get white light passing through prism either as a beam or the classic caustic blob of light.
I tried:
Crystal and crown glass.
100% and 2000% intensity.
Light cone and no light cone (mostly to make the light beam show up).
Light thru transparency.
Caustics enabled and not...
Ray depth 8 and 25.
Filter sharpness 75% and 100%.
Caustic Filter size 25 and 100.
Lighting quality a number of settings up to and including best.

I am beginning to wonder about my spline object...

SIDE NOTE:
By the way, nice job (Laksys) of the creating a soap bubble on the Daz3d site. Plus, great use of logic to figure that out.
Attachments
prism_2.jpg
No rainbow...
prism_2.jpg (11.22 KiB) Viewed 379 times
Last edited by VitalBodies on Tue Apr 01, 2008 1:36 am, edited 1 time in total.

User avatar
Lakys
Site Admin
Site Admin
Posts: 5191
Joined: Sun Dec 12, 2004 3:30 am
Contact:

Post by Lakys » Tue Apr 01, 2008 12:27 am

Nice attempt...

but I fear that Carrara won't handle dispersion and that you need to fake it to show out the color spectrum. :?

http://en.wikipedia.org/wiki/Prism_%28optics%29

User avatar
VitalBodies
Technician
Technician
Posts: 329
Joined: Mon Feb 04, 2008 2:48 am
Contact:

Post by VitalBodies » Tue Apr 01, 2008 12:38 am

Wikipedia is where I got the shape and IOR.
Right now I can not get caustics to work, even though they were working earlier.
Might be my prism/spline object.

or...

When shading the prism do I just use the top level or do I shade every side?
Upon changing my spline objects more sides keep appearing in the materials editor.

User avatar
VitalBodies
Technician
Technician
Posts: 329
Joined: Mon Feb 04, 2008 2:48 am
Contact:

Translation...

Post by VitalBodies » Tue Apr 01, 2008 3:27 am

but I fear that Carrara won't handle dispersion and that you need to fake it to show out the color spectrum.
So are you saying that you KNOW this is so, or just think it might be?

Fear, (in the context your are saying it in) in my language, is a bit like you "think something is so" but with the added fear element added.

User avatar
VitalBodies
Technician
Technician
Posts: 329
Joined: Mon Feb 04, 2008 2:48 am
Contact:

Rendering Room

Post by VitalBodies » Tue Apr 01, 2008 5:11 am

Rendering Room
Attachments
render_room.jpg

User avatar
VitalBodies
Technician
Technician
Posts: 329
Joined: Mon Feb 04, 2008 2:48 am
Contact:

Texture Room...

Post by VitalBodies » Tue Apr 01, 2008 5:12 am

Texture Room...
Attachments
texture_room.jpg
Texture Room...

User avatar
Lakys
Site Admin
Site Admin
Posts: 5191
Joined: Sun Dec 12, 2004 3:30 am
Contact:

Post by Lakys » Tue Apr 01, 2008 6:32 am

Well that's the limit between CG to fake physics. We start seeing some spectral model in applications such Vue Infinite, but it is still not able to produce dispersion.
Having a physics fully accurate model would be too costy in render time.

Good luck :)

User avatar
VitalBodies
Technician
Technician
Posts: 329
Joined: Mon Feb 04, 2008 2:48 am
Contact:

Fresnel shader...

Post by VitalBodies » Tue Apr 01, 2008 6:40 am

Last edited by VitalBodies on Tue Apr 01, 2008 6:50 am, edited 2 times in total.

User avatar
Lakys
Site Admin
Site Admin
Posts: 5191
Joined: Sun Dec 12, 2004 3:30 am
Contact:

Re: Fresnel shader...

Post by Lakys » Tue Apr 01, 2008 6:47 am

Interesting, even if I am doubtful it would be able to render a rainbow from rain and sun within an hour.

But it may be the way to go for your prism case.

User avatar
VitalBodies
Technician
Technician
Posts: 329
Joined: Mon Feb 04, 2008 2:48 am
Contact:

I struggle

Post by VitalBodies » Tue Apr 01, 2008 6:50 am

What I struggle with is, are we (mostly me) not knowledgeable enough to tweak the setting to make it happen or can it not happen.

I now have a glass that can block the light cone but not the light.
Earlier I had a solid (the cube) that the light cone would pass through.
I now have no caustics even at 500%?

Transparency and SSS both have fresnel.

User avatar
VitalBodies
Technician
Technician
Posts: 329
Joined: Mon Feb 04, 2008 2:48 am
Contact:

Post by VitalBodies » Tue Apr 01, 2008 6:51 am

If this worked what would be the important settings?

User avatar
Lakys
Site Admin
Site Admin
Posts: 5191
Joined: Sun Dec 12, 2004 3:30 am
Contact:

Post by Lakys » Tue Apr 01, 2008 3:49 pm

Maybe you should try to put some sheet of paper. Note that caustics aren't gels and are supposed to appear on a surface. I guess there probably also some volumetric way to handle caustic, but it might work differently.

You should not use SSS here, it is useless.


User avatar
Lakys
Site Admin
Site Admin
Posts: 5191
Joined: Sun Dec 12, 2004 3:30 am
Contact:

Post by Lakys » Wed Apr 02, 2008 3:39 pm

Still, you can hardly find a renderer providing an accurate model of the light. This is reaching very high-end features, and our renderers aren't ready for this.

If there were, there wouldn't be any problem to render a realistic diamond jewel.

User avatar
VitalBodies
Technician
Technician
Posts: 329
Joined: Mon Feb 04, 2008 2:48 am
Contact:

What can these do best...

Post by VitalBodies » Wed Apr 02, 2008 5:29 pm

That brings me to my next question. This question is a bit more challenging. What can we say about the strengths or weaknesses about the programs we use DS and C6. Or how can we better know this?

Example: there is no reason to try to render light through a prism if the program can not do that.

Or to try to paint a painting with a shoe...

Post Reply

Return to “Carrara”