lights are flickering! Tweet

[aesq8]

I created a movie theater scene,
but when I rendered a test animation video, the footage was unusable because lights were flickering/blinking on the walls and everyware.

Video link: https://youtu.be/TpCiDKCcgp4

Lighting sources:
The main screen: is emitting using texture emission.
Mobile phone: is emitting using texture emission and a visibly hidden octane area light.
Green emergency exit: blackbody emission using green RGB spectrum.

Render settings: attached

please let me know if there is an option or a method to ensure a clean and smooth animation render.

[boxfx]

The problem is coherent ratio, set this to 0.

Coherent ratio will lower your render time, but it exchanges flickering on a per-pixel level for flickering across large areas of your image. You can only use coherent ratio in an animation with much higher sample rates, minimum of 500 samples but realistically its safer in the 1000+ range.

If you need to speed up your render there are other things you can do which will be far more effective:

There is no reason for this project top use path tracing, there simply arent any visual elements in the scene which will benefit from it. Instead switch the kernel to direct light and change the GI mode from ambient occlusion to diffuse so your screen illuminates the room.

Enable adaptive sampling and set the values to 0.07 noise threshold, 64 min samples and 4x4 grouping

If this isnt enough then enable static noise and turn denoised beauty pass in the main c4d octane render settings.

[aesq8]

The problem is coherent ratio, set this to 0.

Coherent ratio will lower your render time, but it exchanges flickering on a per-pixel level for flickering across large areas of your image. You can only use coherent ratio in an animation with much higher sample rates, minimum of 500 samples but realistically its safer in the 1000+ range.

If you need to speed up your render there are other things you can do which will be far more effective:

There is no reason for this project top use path tracing, there simply arent any visual elements in the scene which will benefit from it. Instead switch the kernel to direct light and change the GI mode from ambient occlusion to diffuse so your screen illuminates the room.

Enable adaptive sampling and set the values to 0.07 noise threshold, 64 min samples and 4x4 grouping

If this isn't enough then enable static noise and turn denoised beauty pass in the main c4d octane render settings.

I can't think of any better reply!! thank you so much for the straightforward and very useful information.

question, that was a test render, my target max sample rate for the final export is 1000,I have 2x 2080 ti, time won't be a huge deal... so should I also stick to zero coherent ratio? or should I just do it in DL mode and it will make no difference? (the only reason I choose PT is because it looked more realistic) I'm beginner in Octane!

[boxfx]

For the majority of projects there will only be subtle differences between path tracing and direct lighting so long as you dial in the right settings. The main difference people notice when switching between the 2 is bright images from bounced light and clearer glass and liquid, but so long as you switch the GI mode to diffuse so that the light can bounce, maybe give diffuse 1-2 more bounces if needed, then bump up specular and glossy/reflection depth so light can travel through glass more and give more reflections, the results will be very very similar for a much lower render time. Generally I would reserve path tracing for times when there are complex refractive objects where light needs to bounce through them to illuminate the surroundings.

Coherent ratio is safer over 1000 samples, but I tend to leave it switched off out of sheer laziness, as it makes the live viewer flicker random colours which is quite annoying. Just render 3-4 frames with high samples and see if they flicker, youll likely be safe. In my experience 0.5 coherent ratio is a broadly good setting if using it.