Internal lighting for a model

[jim c]

I posted this on 3dbuzz, but thought I'd post here too, just in case. I'm trying to add lights to my model and ran into a couple of issues. What I want is to have various parts of the model emit light, such as intakes, or certain parts of a grill, and have a "glow" like effect.

At first I tried using the glow material (from the Material palette) with the emit property turned on. This is cool, but only seems to work if you already have a light shining on it.

Next I tried to create a translucent material*, and put a light inside of it. This is much better. However, to do this so that just the one specific bit of geometry "emits" light, means that I have to basically build a sealed box behind the emitting shape, which encases the light object.

I noticed that putting a single area light inside the model resulted in all of the glow materials being lit up, without an outside light. This was cool, but surprised me, since the glow materials were acting in a translucent/transparent fashion.

This is what I have so far, all of these are "lights" are just sections with a glow material, and a single area light (set to a line/tube) inside the model.

So my question is, is it better to add individual lights? Does it even matter? Ultimately I would like most of these areas to cast out light in the form of a spot light. Will that mean an addition set of spot lights, in addition to the internal lights to drive the "glow"? Currently I'm just randomly trying things, and I was wondering if there was a preferred technique that people would use for something like this.

*The translucent material was made like so:

- a surface shader

- pull in a normal from the global node

- negate the normal

- normalize the result

- feed this into a lighting model set to lambertian with a diffuse color

- take the result and feed that to the output color

[sam.h]

For the internal glow I think what you are doing is good, I did something similar a while ago and used a surface attribute that defined the light position and used that to do the translucency. But I had 100s of glowing cube so I was trying to avoid adding lots of lights.

For the glow affecting other objects in the scene .. it doesn't make much sense to me to have them as a kind of spotlight... since they look soft and translucent it suggest that it would be really diffuse. For light emitting you could use PBR in a separate take / point or spotlights on each spot / another take where everything in the scene is a glossy reflective material and the glow points are phantom.