SPEED UP Render Times in Blender

[@Benn25]

Don't hesitate to render BIG and scale down the size after. the denoiser will handle the noise WAY better, even at low sample, for a better end result on same render time (as you said), and since the denoiser (and compositor!) works on GPU now, it will be lightning fast. personally I render at 200%, with relatively low sample. if this is too much, you can render with an non uniform scale (half the res on X and the wanted res on Y, then put 200%), then unsquash it in post (or compositor) after applying glow/glare/grain. It will have the same look as an anamorphic lens and it will render twice as fast as a fully 200% size render. motion blur and DOF (especially if the cam is close to objects) will impact render time quite a lot. For animation, it may be wise to deactivate noise threshold, especially if you don't have a way to suppress the temporal noise in post.

[@willurquhart3D]

Yah that’s what I generally do. I’ll minimum turn it up to 120% but usually go to 140% or 160% and sometimes 200%. It helps a ton with reducing flickering and denoising artifacts even when turning down the sample count as you said! Forgot to mention motion blur making the render times longer!

[@Mr.Doruko]

@@willurquhart3D Can you make a video of the part in this explanation in detail. Especially the part I need compositor details. ty

[@willurquhart3D]

@@Mr.Doruko Yah of course! it may not be out for a bit so I'll try to explain here for the time being. Essentially when you increase the resolution, you are also increasing your pixel density. it reduces noise a lot because each pixel becomes smaller meaning you get overall, more information despite not increasing sample count. if you do some math, you can reduce your sample count to match up with your resolution and essentially just get a better render (less noisy, cleaner) without increasing your render time. Big benefit because you don't have to sacrifice quality for better render times. Then later when you downscale your image from 4k to 1k or 2k, all those small pixels get smaller and the noise becomes pretty much invisible. As for the compositor, generally the compositor will only add about 2 seconds to render times per frame. So if you can use a mist pass with the compositor you should. sometimes mist behaves strangely with things like transparent shaders, so it might not always work. Mist also doesn't have as much detail and customization ability as volumetrics so it doesn't always result in a better final render. You can always use the compositor for bloom, and basically make emission shaders appear brighter than they are/ that they are glowing (meaning you don't have to crank your emission strength super high and risk higher render times or noisier images). The denoiser doesn't have to use to compositor, you can simply turn albedo and normal on for the denoiser in the render settings, originally however I don't believe that was an option so using the compositor generally gave a better final result regarding denoising.

[@MyBlends5]

i use 0.5 for noise threshold with denoiser on. it looks kind blurry, so i use sharpen filter. but the animation with motion blur messes everything up. my scenes are not as complex as yours so it works out, somehow. thanks for the tips! 😉

[@willurquhart3D]

Any time! Noise threshold is probably the best way to speed up render times but it’s always at the cost of quality. More and more lately I’ve just kept the noise threshold at the default or raised it just a tiny bit. It’s a longer render but I know that if everything else works fine I won’t be re rendering because of any flickering!

[@ialebedev]

Woooow!! Thats really really great trick!! Switch from CPU to GPU! WOW!!!! What a great optimisation! This trick is the same as "buy another extra powerful PC"

[@willurquhart3D]

Lol, the video is about getting faster render times. If you don’t have a computer with a gpu, sorry. I didn’t for 5 of the 6 years doing blender and I did fine. There’s other tips in there not related to gpu to get faster renders and to optimize your scene. Maybe consider watching more than 2 minutes!

[@ialebedev]

I do have really fast GPU, I even have a very powerful renderfarm. But switching from CPU to GPU is not optimisation at all. It is like "if you want to drive faster, buy sports car". It is stupid )). There is no need to be a professional to do optimisation like this one. There are so many videos on KZbin with such screaming topics "Speed up render cycles from 2h to 18sec" and the first advice is to switch to GPU. That's stupid. You think users are so stupid that don't use their GPU if they can?)

[@willurquhart3D]

Some people might assume it’s active by default. It’s not very intuitive that you have to go into the preferences and select your gpu vs the device tab activating it when you turn off cpu. Just because you know where the button is and what it does, doesn’t mean that everybody knows. New people start learning blender everyday and the video is catered towards someone who is just picking up blender, and also someone who has worked with it before.

[@willurquhart3D]

Also idk where in the title or anywhere I mention optimization. The video is about which settings to change in order to improve render times. I mention maybe 2 optimization tips, but other than that it’s just render settings. Don’t really understand what you mean there’s no need to be a professional.. obviously. I’m not making videos for pros. You know why? Because pros don’t need videos, they’re already pros. Like I said before the videos are for new users or intermediate users. Also Go find one video about faster render times on blender that doesn’t mention activating the gpu. It’s in every video because turning it on makes the render faster.

[@Mr.Doruko]

I am saying this as an impartial viewer, while there are so many useless videos on KZbin on this subject, you come and criticize this video badly. I feel like your aim is different. I can say that this is one of the most complete videos on this subject. He explained it step by step, showing his experiences and put in effort. I think it is a great content.

[@orcanimal]

The number of light paths affects render time so little you might as well just put them all on max (32) to get the best quality as it'll only increase render time by miliseconds, if that. Also, Fast GI Approximation is unholy blasphemy never to be used or even uttered!

[@willurquhart3D]

Hahahah yah true to the light paths, I never change them unless I have transparent textures. And fast gi approximation.. I maybe got mixed up at that moment.

[@willurquhart3D]

Or are you saying it’s unholy because it looks worse?

[@Benn25]

Everything you said is right.... in certain cases, false in others! The truth is that all of this is complex, and heavily scene dependant, meaning that you will have to try out to be certain that one option is better or not FOR YOU. persistent data may screw up your renders sometimes, but it may improve drastically render time in some other cases, and may also add render time in other cases! Same with fast GI approx. you can't tell for sure what effect it will have on the scene before trying (it helped me in the past).

[@willurquhart3D]

Yah, I usually don’t use it and in fact I think I’ve never actually used it for a final render (fast gi). But that’s what I was attempting to convey at the end. Just doing the exact same thing I did isn’t always going to speed up renders so you have to play around and render a frame to find what works. Also in a lot of cases, the scene itself is the main problem. Gotta find the problem areas with textures and materials or lighting and you could potentially make render times go down by 1000% by just turning off one light!

[@Benn25]

@@willurquhart3D there is an addon that analyse the scene and give you what is impacting the render time the most. didn't try it so I don't really know how good it is, but it seems very handy if it works as intended.