OTOY Forums

Hey guys, i'm struggeling with the spotlight.

For a customer project i need to recreate a simple spotlight like on a stage (image 1).




If i use the standard spotlight without any other lights, it works great (image 2).




But the moment i add more lights than just the spotlight, the whole system fails (image 3).




I tried to play with the settings and hide the other lights with the "Lights pass Mark" function, but the spotlight ignores it (image 4).



What worked a bit, was deactivating "Alpha shadows". But this lead to other problems that made it even worse.
Has anyone already stumbled upon the problem and may know a solution?
Thanks in advance
Michael

Thanks elska, but i don't know what to do with your answer. I'm here because of the "tweaking" you're talking about. Can you be more precise?
Your link does not really deal with the subject.

Thanks for the effort, then i'll wait for someone who understands the issue

I'll wait. Maybe someone knows a trick on how to get it to work in that lighting combination

Hi Korma, I have had the best results "building" a light fixture that mimics the way actual spotlight fixtures work: they consist of a globe (light source), a dish reflector behind the globe, a simple cylinder for the overall housing, and an (optional) fresnel lens in the opening for the light to exit. If you make the interior of the housing white, you can get away without the reflector. The key is the distance of the light source globe from the opening of the housing. Closer to the front opening the spread of the light will be broad; the closer to the back of the housing the beam will be more focused. I rigged up some simple Xpresso to control this relationship (spot to flood). You can also go crazy and fashion bard doors or use digital versions of flags, scrims and so on (it helps if you have real-world lighting experience.) For the light emitter, you can use an area light (circle-shape) or fashion your own emitter polygon, which some argue can be tuned a little more than the standard Octane lights.

Of course, if you want to "see" the beam, you need a volume medium of some kind. Elsksa described the Octane "spotlight" and how it works and you could do the same. It is common to put the volume around the scene components, and others have done so just around the lights. If the overall illumination is dark, you might be able to get away with that, but if you have a lot of bounce lighting and your overall illumination levels are brighter, you will need an encompassing volume.

Note that the volume medium will be the noisiest in the brightest part of the cone. In fact, most lighters will not use that portion of the cone for illumination in the real world, as the center area of the cone tends to be the sweet-spot. A good read up on set lighting technique is a good idea. Octane is physically-based, so mimicking real-world techniques is the best way to go. This technique will also play nice with other lights that you might have in the scene.

In terms of sampling, you will have noise with the volume medium. That will take samples to deal with. I have found that that PMC kernel is the best for a pleasing spotlight cone, but it is also by far the slowest of all of the kernels. If you are animating, the PT kernel would be better for time (though noisier) and you could work with the denoiser settings to get a look. You are going to need a good amount of samples to resolve the noise to the point that the denoiser can give you a cleaner result.

Here is the resulting image:

Thanks guys, but a volume is not an option in my case. I thought that was clear, maybe i should have mentioned that there are good reasons why i wanted the spotlight for that project. I have several hundred spotlights and it's simply impossible to artdirect them with a volume. I now have a nice solution by combining the Cinema 4D standard renderer with Octane by rendering two versions and combining them in post. This way it's even possible to achieve results with IES lights that are simply impossible with Octane without spending days. There it's just drag and drop different IES lights and it renders in seconds. It's crazy easy and fast.

The tip came from Facebook: https://www.facebook.com/groups/OctaneR ... nt_mention

elsksa wrote:Although this wouldn't be viable in production..

Yeah elska, i'll tell this to my customer when he asks why i spent 95% of the budget on spotlights

I was talking about art directing hundreds of lights... nevermind.

In our experience, you're better off rendering visible and volumetric spotlights in c4d's standard render engine and just comping them over the octane renders. Visible light cones in octane are very uncontrollable as far as art direction goes, you either end up with a misty smoke filled room or incredibly long render times as you try to resolve the noise generated by a small bright light shining through a 3D volume.

I'd love to be proved wrong on this with a c4d project file, but we basically gave up trying a while back

Have you tried the 4dm light kit spotlight? That one works pretty well. You could also fake the spotlight volume with a cone mesh and the proper material.