PDA

View Full Version : Bending light beams with a magnifying lens



mediamonkey
07-04-2007, 04:29 PM
Hi there everybody,

I'm a relative new-b to Lightwave and could really benefit from all your experience.

I have set up a scene where a light shines through slits in a vertical object placed on a table. This creates three parallel beams of light along the table.

These beams of light then hit a convex lens similar to a magnifying lens. In a real world scenario, we would see these beams refract through the lens and bend inwards on the table, converging to a focus point.

I have tried using caustics but can't simulate the real thing. Can anyone suggest a way to do so. I am not above 'cheating' to create the effect. : )

Thank so much in advance. Even pointing me in the right direction would be greatly appreciated.

Cheers.

jameswillmott
07-04-2007, 04:34 PM
Draw a luminosity map?

mediamonkey
07-04-2007, 04:49 PM
That's a great idea and so simple. This would work for a still and I may end up heading in this direction. Thanks!

Ideally I would like to animate the lens moving across into the beams, which would cause the refracted beams to swing around independently to cross at the focal point.

Is there a way to achieve this? ... if not, I'm sure I can work around it now. Appreciate your help. Thanks again.

byte_fx
07-04-2007, 10:25 PM
have a general but not specific idea of what you want to do so these are kinda general:

use three luminosity maps - one for each light beam.

parent a null to the of the lens and move along the apropriate axis to the focal point of the lens.

parent a null to the lens, positioned in the middle of the lens thickness, at the point where each beam hits the lens and yse the null at the focal point as their targets.

parent another null to each of those and use - presumably - y value of the illuminated surface to set their y values thru either channel follower or sticky.

parent the lum maps to those nulls and use the difference in their y values to control the map sizes.

as u saud - kinda general and could use some tweaking but something along those lines shoyld work pretty well.

you might even consider using thise values to vary the percentage of the maps a bit so they're brighter when at the focal distance.

byte_fx

Edbittner
07-05-2007, 05:40 AM
byte fx has it. Never forget CG is ALL fake. Just because new tools make life easier in some instances, all cannot be used for everything. When in doubt, fake it. I remember before LW had Vol. lights, we used cone shapes with edge transparency. Same difference.
E.

colkai
07-05-2007, 05:52 AM
I remember before LW had Vol. lights, we used cone shapes with edge transparency. Same difference.
E.
Like as not as maybe, a lot of folks still do. :)