OTOY Forums

Hi there,

I've been having trouble understanding the exact function of the light sample rate. From the manual it's clear it's to balance the weight of samples a light recieves, which cleans up grain. but what is the exact relationship?

Is 'weight' simply a priority or proportion? Therefore could three lights be set at '1, 2, & 3'? In tutorials I've seen people setting values such as 2600. The default setting is 100 - is that 100% or 100 samples?

Is the 'weight' a division of Maximum Samples setting in the Kernals menu? For example if max samples are set to 2064, with three lights all set to a sample rate of 100, then do they recieve 1/3 of 2064 each? Or 300 samples?

Generally increasing the sample rate appears to clean up grain, but in one test, I increased the sample rate of a light close to a wall & it became much birghter & burnt out. I've also noticed that when I use the render region to focus on an area, the grain appears to behave differently to the full image (it becomes much sharper).

Any help/explanation greatfully received!! I'm on a job working with Octane, so gaining understanding & control of these basic functions asap is pretty important!

Hi,
the sampling rate in the emission node is used to balance the importance and contribution of different lights in the scene.
The classic example is the room with spotlight and tv screen. The tv screen contribute less than spotlight to the general illumination, so you can lower to 1 the sampling rate in the tv screen material, leaving at 100 the sampling rate of spotlight.
If you increase a lot the sampling rate, the importance of the soecific light will be higer, and the emission results more brighter than expected, but you can play with this effect to force the engine in particular areas.
If you set the sampling rate to 0, the light will not contribute to the direct light calulation.
ciao beppe

but you cant set it to 0 in c4d because it always sets itself to 0.0001 when you type in 0 and hit enter

Well I must say that is one things that I really don't like of Octane.
I understood that could be really useful to give more sample to a light in order to avoid noise in some areas, but it's not clear and not easy to manage why the light with more samples should emit more light than the setted value.

Am I the only one that don't like that?

GIOLETS wrote:Well I must say that is one things that I really don't like of Octane.
I understood that could be really useful to give more sample to a light in order to avoid noise in some areas, but it's not clear and not easy to manage why the light with more samples should emit more light than the setted value.

Am I the only one that don't like that?

No i agree, i dont understand the logic behind many things in octane. I didnt even know it becomes brighter, doesnt make sense, it should only affect noise. And i was about to ask cause i got a scene with various light sources and cant get easily rid of noise. Anyways..