OTOY Forums

Below is a progress render of a job I just started.

I was experimenting with kernels to see what affect each had on noise. As you can see, I'm getting loads of sparkles. I can eliminate a bunch of them with hotpixel, but I don't like the blurring effect. I can increase render times of course, but I figured I should first check to see if I'm doing something wrong. Sun/daylight is Octane system. Hanging lights use emitters with physically correct settings. Emitter sample rate is 100,000.

Anything I should be doing differently?

Try adjusting GI Clamp (should by default be about 1000000). Try setting it to 1. This will "contain" lights to only areas it can sample well. Putting this too low will darken your scene and start making bounces not visible, but it will keep your noisy speckles down quite a bit in the right scenes. Usually a good value is between 1 and 4. Keep in mind this makes the render slightly biased as you are clamping light intensity/contribution.

Thanks! I've just begun playing with that setting (and a few others I was unaware of!)
FIngers crossed....

Are those objects a solid surface with a separate material for the light at the bottom or is the light source contained inside a hollow shape.

Light source is a black body emitter material on a rectangular face that is up inside the light fixture.

If you look carefully, hotpixel values above 0.7 don't blur much at all. 0.7 will get rid of the most and sacrifice the least, but 0.8 is usually a great place to start without sacrificing clarity. Save out some side-by-side comparisons and cycle through them. In the end, maybe dealing with the noise or its solutions is actually much worse than very slight blur.

jscottsmith wrote:Light source is a black body emitter material on a rectangular face that is up inside the light fixture.

In that case what you can try is apply a pure black material to the inside and make it a passive emitter ( turn of cast illumination ) and you should get a much better result with less noise. What it does is reduce energy from reflected light and this is what is likely causing this high amount of noise in your scene.

PT will give best results for that scene, ie better looking lighting, but set caustic blur to 1.0 will also make a big difference. Using bigger fake invisible lights is another strategy.