View Full Version : realistic plexiglass

08 August 2005, 01:29 AM
does anyone know the best way to model and render a piece of plex so that light transmits through the edges realistically?

a piece about 1/4" thick, 4" wide and 96" long, stacked on a bunch more


08 August 2005, 02:30 AM
hi pdrake, here's a couple good tuts on glass/transparent materials, i hope u dig something

for the 'light transmit through the edges realistically' part, as far as i know, u have to create a copy of the model scaled down slightly and make different surfaces for the polygons facing inwards-outwards with different refraction index.
as far as i can remember those two tuts have similar concept

i hope it helps, Good luck

08 August 2005, 03:06 AM
thanks, i'll give that a try. i'm not having much luck so far.

08 August 2005, 03:30 AM
The tutorials probably won't go over it. The reason why light seems brighter coming out the ends is because of internal reflection. For LW to really do it correctly you would need to render out caustics with hundreds of bounces in between the inner surfaces of the plastic or glass. Since that isn't realistic (or even possible since caustics don't multi-bounce in LW) you need to figure out how to fake that. It may be something as simple as sticking a polygon inside the plexi near the edge and over-cranking some values.

A poly with:*
99% transparency
0% diffuse
5000% translucency (you are fighting the 99% transparent)

This looked pretty good for what I was trying to get.

This is for plexi with polished ends though. I'm not sure what your stack of plasic is doing so you might just ahve ends that have saw marks in them.

*If you do this type of setup and make the inner poly dark green you might get a good glass pane.

08 August 2005, 04:42 PM
heh, i think i figured out a way to fake it enough for the client.

i gave the edges a very high luminosity. they'll never know the difference.

i'll post a render later.

08 August 2005, 02:17 AM
2 Tips:

1. Air Polys - copy the area of the plexiglass to another layer, flip the polys, and give them a new surface with 15% diffuse, 100% transpareny. This helps LW's renderer to correctly bend the light (assuming you assigned a refraction index other than 1 to the main surface).

2. Make sure that you turn on "Ray Trace Transparency, Translucency, Reflection and Refraction" in the render options panel. For added realism, you can turn on shadows as well.

08 August 2005, 07:39 AM
Why don't you guys simply use fresnel reflections and refraction? no need to use caustics or other fancy stuffs, since the fresnel equations resolve the internal bouncing of rays....

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08 August 2005, 07:39 AM
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