I have been learning about Blender for 1.5 years. I started to work on my short film half a year ago, but I only had an old computer, I could not render anything out. My new machine has just arrived, but my first render does not look very impressive. I see these flickering lights on the surface and the scene is just not sharp. Please see the link: https://www.youtube.com/watch?v=UeaMi2m4db8
Can you advice me what it is. Is it just noise?
I render this scene in :
Cycles
1920x1080
100%
Format: FFmpege Video
Coding: H.256
Quality: Perceptually Lossless
Max Bounces
Total: 12
Diffuse: 4
Glossy:4
Transmission: 12
Volume: 3
Transparent: 8
(I donât think I touched these settings)
Noise threshold: 0.1000 (only)
Max sample: 256
Denoise turned on
Everything else must be default (as far as I know)
What denoiser did you use, Optix or OIDN? Also, change âNoise thresholdâ to 0.005, so more areas receive more samples, which might be the reason why youâre getting these flickering splotchy areas.
Also, instead of writing it all, you can simply post screenshots of all your render settings so we can see exactly what is up. If you donât mind going further, sharing your .blend file will give us a chance to look at your scene setup as well and see if thereâs anything light object related which might be contributing to the problem. Weâd also get a chance to work the settings and find the best values to use to get the best render.
Here is a screenshot. I hope it helps. I am not comfortable sharing the entire blend file. I know it is not much, but I worked on it for several moths with my very limited knowledge. It is only a couple of minutes long, but at least it is mine.
This is a scene with multiple things that will make the render noisier.
There are multiple emissive meshes. geometry that emits light is noisier than light objects. If your main light sources are meshes, replace them with point/spot/area lights where possible.
I canât see if thatâs a problem or not in your scene, but be careful about hiding a light source deep in a hole: that will increase the noise, as light rays will struggle to connect to the light source.
You have glass objects, including a giant glass tube in the middle (by the way, you may want to activate auto-smooth on it, it looks like the shading is distorted because the ends of the cylinder arenât shaded sharp). Glass materials tend to be noisy in Cycles, because light rays struggle to find light through them. This can be fixed by using the glass shadow trick.
Itâs an interior scene. That makes it a more difficult case by itself, but you also have lots of semi-glossy materials to make it even harder. This means you will have to use higher sampling settings if you want a good result.
I would set the max samples at 1024. This will help the more difficult areas, but the render quality will now be mostly decided by the treshold, as it will be the main thing that will stop the render instead of the max samples.
I would set the min samples at 128 (if you leave it at 0, Cycles picks a value for you, which might be too low for your scene). Interior scenes + glossy materials tend to benefit from higher min samples. If you pick a value thatâs too low, the treshold might stop sampling parts of the image too soon and miss some important reflections, because they didnât even have the time to appear before the treshold stopped that part of the image.
The noise treshold of 0.1 is a low quality value, especially in a difficult scene. Itâs going to stop the render way too soon and wonât be able to refine the harder parts of the image. I would lower it to 0.05 or maybe even as low as 0.02.
Is there volume fog? If yes, thatâs going to make the render longer and noisier. You could render the fog as a separate render (with every other object set to holdout) and composite it on top afterward, if you have the knowledge. If not, maybe you could remove the fog and instead fake it by using the âglareâ node in the compositor, set to âfog glowâ. Itâs not real fog, but it can somewhat imitate the same light glow effect. Or you could just accept a longer render time and leave it the way it is.
If I was rendering this scene, I would personally bake the diffuse lighting as 32-bit images on the main walls and ceiling and then use that bake as emissive textures. This can speed up a render by a considerable amount, as the walls are basically pre-rendered.
This isnât always the case anymore. If there are âsuspect lightsâ (i.e. varying strengths and areas) in the scene, Iâd recommend testing out how they work in isolation and combined.
