Volumetric lighting from emission shader objects in Cycles

Hi, I am trying to recreate the Eurovision stage in Blender. But I am having an issue with volumetric lighting. As an example I put the winning performance here, you can see the lights flashing around, and at the start the lights blending in and out. I want to do that with the volumetric effects.

As you can see in this test I have managed to get the lights blending in and out but no volumetric lighting…

I want to add the lighting to this sort of animation… However if I simply used spotlights then I’d have to animate each individual light which considering there is so many would take a very long time. So I am using an emission shader with the use of a wave texture and a color ramp to get the lights to work this way. However whilst a spotlight does produce the desired volumetric effects, the emission shader doesn’t seem to do that. And I am struggling to find tutorials on what I am wanting to do…

So my question is, when using an emission shader as a light source, whats the best way of getting good volumetric effects that reacts to the emission rather than manually recreates it (like a light cone)?

Many thanks
Matt

Hi Matt,

two things about your problem:

  1. The light sources that you are using are “soft lights” because they are emitting light in every direction. So you can’t get any nice shaped light effect because your light has a diffuse shape witch is practicly no shape. The best you can get from this is a glow effect. If you take a closer look at the real footage you showed, you’ll see that only the spotlights produce your desired effect.
  2. Even if your light sources would be spotlights you wouldn’t see any effect as long as these spots are pointed towards the camera. Only light beams that go cross the view can be visible by illuminating the volume. When the illiminated volume is infront of something bright, you can’t see it because there is no contrast between the for- and the backgroung. Watch your real footage again and you’ll see, that you only see the light cones, where the background is dark.

So you need hard lights and accordungly hard shaddows to get what you want. You can use spots oder a sun with a realy small angle for this. And the direction of the light should be across the view.

I hope that helps :slight_smile:

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Hi, in response to your post I tried turning the LEDs off and still there is no visible LED beam… Here is a comparison between the spotlight and emission, here is what i did…


Is it possible to do light sequences with spotlight like with emission lights? As you see from my video, with the emission, I was able to make it so the lights next to each other turned on in sequence… Is it possible to do that with spotlights without having to animate them individually…

Could you use a world volume scatter with anisotropy?


This is the result of that, as you can see not much volumetrics yet

Doing some testing, If you want to have a visible beam with mesh lights, you would have to insert them deep inside a tube (or have clusters of small tubes, to save some space).


However, this increases the noise quite a lot, and it would be even worse with the number of lights you have. In this scene, mesh lights+volume might take a very long time to render.

A possible alternative to this might be to manually create fake beams with meshes and plug an emissive material in the volume (I am including an exemple file).
fake_beam.blend (817.9 KB)

You can also use area lights and give them a spread angle of something like 10° oder 20°. That’s restricted to circular or quadratic shapes but it works fine (in Blender 2.93 and higher).

Yes, that would work well and I might actually choose do it that way myself, but in this scene here, he would need to add a light object to every lamp in the scene and animate them. Maybe it would be worth it to do that, or maybe the mesh light setup he has can be good enough with a bit of tweaking. However, I have never tried something so ambitious with mesh lights+volumes and the render times might get crazy.