OTOY Forums

Hi,
I am trying to setup IES in a scene. Everything works fine but when I decrease the opacity of the emmiting mesh to "0" the light behavior changes as well and the illumination decreases drastically.
Is there a way to use transparent IES-Lights (hidden light source)?
With standart blackbodies it is working but I need IES lights in this case.
Any thoughts?

Isn't so for all the light sources; if you decrease the opacity to 0, you don't get any illumination? AFAIK, we can't have invisible light sources in Octane.

I use Blackbody emission and set a x.ies file as a floatimage for Distribution. Works everytime for me even as transparent.

It is really strange. In my scene the strength of the lights (even used as simple mesh lights) changes if I play with the opacity.
In a simple test scene I had no trouble...

Could it be you have too many light sources in your scene?

It depends on the size of your light sources. Our light source sampling currently doesn't handle transparant light sources correctly. Only a part of the emission will be rendered. For a single small light source most of the illumination will be rendered, but in scenes with large light sources or a lot of light sources only a small part gets rendered.

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Roeland

Yes I have many (around 100) IES lights for an exhibition hall in the scene and all of them are large.
Unfortunately I have to hide them.
Will the handling of transparent lightsources improved in the near future?

The proper handling of light sources with full transparency is obviously to make sure you don't see any illumination of them. But that is not what you want. We could add a possibility of a transparent emitter material in the future, but we don't have such plans for the near future.

In what kind of situation would such a transparent emitter come in handy?

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Roeland

There is a roof construction that does only allow lights on specific places. But for render purpose I want the rendering actually look more bright then it would be in reality.

roeland wrote:The proper handling of light sources with full transparency is obviously to make sure you don't see any illumination of them. But that is not what you want. We could add a possibility of a transparent emitter material in the future, but we don't have such plans for the near future.

In what kind of situation would such a transparent emitter come in handy?

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Roeland

WHAT? How about every movie, TV show or commercial ever made? I realize you're probably a programmer unfamiliar with 3D rendering, but it's no surprise that ALL other renderers (that I can think of) have their light sources hidden by default or hide-able. Its been this way for forever. A better question would be, "When do you ever want to see your light sources?" Because that's a rare occassion. And even if you want to see your light sources, someone can always place a non-emissive object in the same place as the hidden light source, which is made to look like a light source, but it'd be far more controllable if the emission and the rendering are separate, which is why EVERY other renderer allows you to hide the emitting objects or light sources.