Object Source Lighting Modeling Help..
January 23, 2015 4:27 PM   Subscribe

Hello! I'm building a miniature and I'd like to incorporate some object source lighting for the first time. However, I'm having some trouble visualizing where the light would go. I'm wondering if you can help.

This is a WH40K Dreadnought that I've been working on for awhile. I've always wanted to try OSL, but I've been afraid I would muck up the model so I always bail at the last second. This time, I've decided to go for it.

Here's a gallery of my current project on Flickr. See the big plasma gun that passes for a right arm? What I'd like to do is have the green from the plasma coils kind of splash onto the surrounding body... This will give a real sense that it's "glowing" hot, and I think it could look pretty cool.

However, I'm having a heck of a time visualizing where exactly that glow would go onto the model body.. I find it's difficult to think critically about how light bounces around.

So, hey, maybe you're better than me. Can you look at the pictures provided and either visually or with words give me a sense of where you think the glow would go on the model body? I mean, obviously I have a bit of an idea - and it depends on how bright I want the glow effect - but I think if someone more skilled than I could give me some advice, it would make a world of difference to how it turns out.
posted by kbanas to Sports, Hobbies, & Recreation (4 answers total) 4 users marked this as a favorite
CG Lighting artist reporting for duty! This is what I do - make glow-y explode-y giant robots.

This is what you're referring to, right?

In CG this is what we refer to as 'interactive' lighting, which is generally very faked and non-physical but goes a really long way to adding exciting visual qualities to objects, especially metal ones.

There's 3 qualities of light that you'll want to pay close attention to:

1. Shiny objects will reflect the source of the light very sharply, which dull objects will look more like 'spill' due to their more (subjectively) blurry reflection.

2. Light follows the inverse square law which means that it goes away very quickly with distance. As mentioned above, sharp reflections on shiny surfaces will stay sharp even far away, but 'spill' light will fall away very quickly.

3. The color of light will be affected by the characteristics of the surface. Shiny plastic things or clearcoated metal (like cars) tend reflect a color purely, while things like dull metal will reflect more of their own colors.

So in the process of painting, the best thing you can do is look at a LOT of reference. Maybe neon tubes? Sparks?

Plan carefully what each piece of your model will be made of, and what particular quality of that material will look when illuminated. Reference, reference, reference.

Feel free to ask any more specific questions!
posted by misterdaniel at 6:11 PM on January 23, 2015 [1 favorite]

I think the gun might have parts glowing, or inside the muzzle still red from fresh shots. Also the helmet thingy might cast a green light up on the face from an onboard console.
posted by nickggully at 7:53 PM on January 23, 2015

Here's an easy way to think about it. Any spot on the dreadnought with a direct line-of-sight to the plasma coils will be lit by them (i.e. if you could shrink yourself to minature and stand on that spot, could you see some coils or all of the coils?). The more coils with line-of-sight, the brighter the spot. Closest spots are brightest, farther spots are dimmer or visibly unchanged. Depending on how "bright" you want the coils to seem, you can tweak this one way or the other.

(You probably don't need to worry about secondary bounces unless there's a part that's a mirror/glass, most video games ignore this and they look pretty good)

The spots I think you should focus on are the lip of the gun itself all the way around the plasma coils, as well as the similar spots where the gun connects to the arm, a fainter gradient on the slanted top, as well as on the side and crevice where the arm meets the breastplate thingy. Like this (red is brightest, yellow is dimmest.)

There also might be some spots where you need to take into account real-life shadows caused by a lack of ambient light, you can try to go even brighter there but it's a bit tricky.
posted by JauntyFedora at 8:04 PM on January 23, 2015

Part of the issue here is that the plasma coil doesn't appear bright enough to actually cast any light. Check out this example of OSL lighting to see what I mean. The green should be much more saturated than what you're using here.
posted by xyzzy at 7:49 AM on January 24, 2015

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