Multiple Lights Questions

[Jedi2016]

This is just a quick question to clarify how multiple lights in Octane works. Apologies if this has been asked and answered before.

To quickly summarize, I've noticed that if I have only a single Octane light in the scene, plus environments and whatever else I'm using, it behaves as you'd expect.

But as soon as I add a second Octane light to the scene, it gets really noisy really fast, until the IPR chews through enough samples to smooth it out. This happens even if the second light is a straight Clone of the first light.

The behavior seems to indicate that additional lights beyond the first one are being treated as emissive meshes rather than just a straight light source. While the end result is the same, it does take a fair bit more samples to get there, even just to preview in IPR.

I just want to make sure I'm not doing something wrong and that I'm not crazy... Is that just the way Octane works? If so, is there a way to more specify which one is the "real" light, or will it always be just the first one?

[juanjgon]

This is how Octane works. Octane doesn't have light sources (unless we are talking about the toon lights), all the lighting works using emissive geometry. The LightWave plugin Octane light is only a tool to work with lights in the scene using the same workflow found in the LightWave native renderer, but at the end, they are converted to emissive geometry by the plugin at the scene extraction time.

So in short: You could build the lights in your scene modeling the geometry to be used as light sources and adding emissive materials to it and the rendering features and performance will be the same than using Octane lights.

Hope it helps,
-Juanjo

[pixym]

Good to know !

[promity]

If the light source in octane is geometry, then why can't we upload Ies files directly to geometric objects with emissive materials?

[juanjgon]

If the light source in octane is geometry, then why can't we upload Ies files directly to geometric objects with emissive materials?

You can, you only need to set the IES file in the texture image node, and probably add a spherical projection to orientate the light.

Thanks,
-Juanjo

[promity]

But IES files cannot be loaded into the Texture image module. Only images.

[juanjgon]

But IES files cannot be loaded into the Texture image module. Only images.

Yes, the IES files can be loaded using the texture image node. You should even get a preview of the IES lighting in the same node, as you can see in the attached image.

Thanks,
-Juanjo

[promity]

wOW! Oops )) Thank you.

[3dreamstudios]

Yes this is great! I did not know that either.

[3dreamstudios]

So testing this out I have some questions. One, how would you get the light geometry to glow bright? Some IES files make the geometry light up and others do not. Attached is an example of both LW lights and Geometry sized the same with applied IES through TEXTURE node. You can see the LW light is glowing white and the geometry is emmiting light but the geometry is not bright. I applied a UV map that fills the geometry for each light.

Second, it seems that the calculation is somehow off a bit. Taking say a 1m DISC LW light and then scaling it down to 6" it's about .146 in scale. So I take the POWER of the light that was on the geometry light and multiply...so for instance 50 power would become 7.6 and the result is very close...but not quite the same. Not a huge deal just wonder why. I can fiddle making it close.

PS: I've attached the scene, object and IES as well for testing if need be.