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Volume Caustics Reflection Limitation Issue
Hi all,
Below I’ve attached an image of a test render. I’m attempting to reflect a spotlight off of the inside of a reflective tube in hope to create a volume caustic reflection. The issue I’m having is that the reflected light from the tube ends the moment it meets the outer angle of the spotlight. In real life this light would continue along the path as indicated by the red lines I’ve drawn. I admit I haven’t used C4D for a while and might be missing a simple setting somewhere.
My goal is to see what the caustics look like continuously reflecting around in this tube and other reflective shapes, hence the need to see the light continue outside of it’s original spotlight angle.
Any and all suggestions would be helpful, thanks in advanced ☺
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4 Replies
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this is what I get in a simple test. The differences from yours are probably – I’m not using a visible light (which I figured would confuse/mask what I was trying to see), I’m not using any other light. I have the energy and photons settings up a fair amount (always go loud (lots of energy) at first to check out where it’s going, then increase photons to get smoothness, then decrease energy to the level you want – all assuming it’s not way too slow to do it that way), and I have no falloff in the light or caustics…
and I’m assuming you really want surface caustics rather than volume, since thats what should give you caustics off a reflective surface rather than through a transparent volume
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Hey Brian,
Thanks for diving into this!
Some more context for ya. I’m working on previs for an installation focused around volumetric lighting. I am specifically interested in seeing the caustic volume the light created and although the surface caustics in the real installation will also inevitably exist, they are not the focus of the work.
Thanks for your pointers on tuning in the rendering for caustics – I used this technique and was able to replicate your look with only surface caustics turned on. After replicating your render, I turned on volume caustics, and got the same issue – The reflected volume does not go beyond the angle bounds of the initial source light. Is it possible this simply hasn’t been built into C4D?
Imagine a rendering of a flashlight in a foggy room. It shines on a mirror. This image would be a beam coming from the flashlight, bouncing off the surface of the mirror, and out at its appropriate angle of reflection, with the reflected beam still appearing to have volume due to the foggy room. A test image of this simple effect is below, with the same problem I experienced initially.
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the way I read the help, the volume caustics are to make visible effects in the volumetric light after it passes through a transparent object.
Relating to your example of the foggy room, the volumetric light is a fake of that and while reflected light does affect the volume of the light cone as it passes back through it from a reflection, the ‘foggy volume’ does not reflect (does not continue reflected) in either standard or Physical – perhaps something to request long term –
I don’t see a way around that except fakes (unless I’ve missed something since it’s not something I’ve used).
Might be possible with other render engines. -
Hmm…
I was worried this might be the case. It would make sense that volume caustics are specific to how the volume of light is effected by a material after it passes through it. Its just simply frustrating that this does not include reflection.
I’ll gladly suggest this to Maxon.
Will have to look into different render engines to see if this is possible.
Is volumetric lighting the only way to achieve this “foggy” effect in C4D. Or is there a way to create an atmosphere of fog in which lights become volumetric?
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