Lighting a dark and scary scene

[jim c]

So I've got a scene that I'm going to be lighting. I want something with some fog, which I've sort of got working, but also with some lights that emit a beam of light, something like a flash light emitting the beam of light in a smoky room. Think the lighting in the Derelict ship in "Alien".

I know how to create the fog. What I'm not sue is how to best have light "emitting" from some object that moves. Ideally a spotlight would be nice, but that converges to this single point, which is not what I want. Is there an alternate approach?

I tried the geo light obj, but it looks absolutely horrible until you get it over 50 samples or more and then it reduces the render times to a crawl.

Are there alternate ways to fake this using post techniques?

[edward]

How are you using the geometry lights? If you're considering post techniques, then you shouldn't render it with your regular scene. You should render your light beam in a separate pass (interacting with the fog) and composite it afterwards.

Or, you can just render out an object matte of your light beam geometry and then apply glow in the compositor. (I'd imagine mostly just blur and over)

[jim c]

>How are you using the geometry lights?

Not 100% sure what you mean. In the test I did, I had a bunch of geometry that I extracted into a separate geo object. Then assigned this to the Geo Light object.

Note the image was rendered *WITHOUT* the geo light (it simply looked too bad, but that was done without passes as you're suggesting).

The white spots in the image show where the light would be coming from, so they are repeating all along the curve of the tunnel.

I guess what I'm looking for is any tips in trying to get this kind volumetric lighting effect. The passes idea is a good one, and I completely forgot about that.

[old school]

Use spot lights that reference IES light maps that you can download from many Light manufacturers. Use the angle in the IES light settings to get nice "flashlight" effects in the volume. I would opt for this over geometry lights which are noisier in PBR at this time.

Definitely modify the Attenuation Options on the light using physically correct and using the ramp along with the Ramp Atten Distance set to the same as the Active Radius (the maximum distance away from the light source that the light will illuminate anything). Boost the light value up until it looks bright enough for the scene.

To mitigate noise you can increase the stochastic transparency samples up on the Mantra ROP output driver.

If you use PBR, you can have light bleed in to the volume but it will be noisy by setting the Volume Limit to 1 or higher.

If you use the Volume limit, you can also add an indirect light to use photons to control the indirect light for the most part to gain some speed back with a bit less noise.

[jim c]

Thanks for the IES tips. I'll post something when I get them incorporated.