OTOY Forums

Hi,

roeland wrote:The sampling rate of both emitters should be set to 1.0 .

I was wrong about this one. The laser emitter has much more power than the cube, so it will by default get most of the direct light samples. Because of the tube there will be no direct light coming from this emitter, so you can set the sampling rate of this emitter all the way down to improve the quality of the light coming from the cube emitter.

As I suspected this is a difficult scene to render for Octane, the chance of a ray being traced from the card through the prism and the tube to the emitter is very low. That is why even after rendering for a while you only see a few fireflies on the card. You will get a better result if you use a small high emitter, and replace the tube with two parallel vertical planes.

There is probably laser light reflecting off the prism, but it isn't hitting anything anymore, so you can't see it.

You should have a environment node connected, if you want a black environment use a texture environment with a floattexture set to 0.

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Roeland

Thank you for looking at the file, Roeland.

I am confused though about there being no direct light coming from the laser emitter. By "direct", do you mean light rays going directly to the picture plane of the viewport with no obstacles in the way, or "direct" as seen by the prism?

You will get a better result if you use a small high emitter, and replace the tube with two parallel vertical planes.

Like a really tall thin rectangle as the emitter? Also, using two vertical planes, could not the top, bottom and back be capped off as well?

At any rate, an answer I got from Marcus on the pushbutton panel thread, says basically the same thing...Octane PT can have a hard time with very small emitters. PMC definitely excelled in that respect.

There is probably laser light reflecting off the prism, but it isn't hitting anything anymore, so you can't see it.

Sorry...Not the laser light but the laser tube. Relative to the camera, the tube should definitely be visible in the prism face. But I just realized something. I set the color of the tube to 0,0,0 to keep a pure beam of laser light coming out of it. There is nothing to reflect in the sense that with all of the light bouncing around inside the prism, a perfectly black tube would be overwhelmed by the light inside the prism passing right through that reflection on its way to the picture plane.

On the bright blue inside the prism (in the PMC image on the left), do you have any idea as to why it is so bright, when the blue floor it is reflecting was so dimly lit?