speed up your renders
  • Hi all,

    Just a quick post (if it turns into something more substantial, I'm hoping to collate it into a proper article) regarding things you can do to speed up those renders and make your life easier. Please feel free to chime in with tips as they come to you!

    NB: this is all based on my own experience, so is no doubt riddled with flaws and inaccuracies..


    Find a plan and stick to it - It's so much easier coming into production with at least some idea of what you're going to face coming out of the other side. A general idea of formats, potential software/hardware issues etc can really inform on overall render time which is a good thing.

    Don't be afraid to light like a pro - It's astounding how many people think that global illumination + ambient occlusion = a lit scene. Both these methods simulate the same effect, and can add varying amounts of time to your renders per frame. A scene lit with a combination of spot and area lights can take dramatically shorter to render, look better and afford more control in post. Do your research and find out how a DOP makes their money!

    Default settings are too high - especially in programmes like Cinema4D. Make sure your ray depth, shadow and reflection settings are appropriate for the scene, that if you DO use GI and AO that you're not calculating detail that won't be seen (go back to my first point....get a plan!) due to motion blur or other effects in post.

    DIY oversampling - some programmes struggle to antialias well - Cinema4D in particular struggles with highly reflective material (overbrights tend to pixellate, especially with field renders) and high degrees of antialiasing seem to reduce my workstations to a gibbering wreck. Try removing antialiasing altogether and rendering at double or triple the resolution... If you've got the RAM for it. This can of course be taken further with oversize renders for specific objects or passes. While I'm on the subject...

    Use a compositing programme!! - break your renders into passes as required and make sure you use your time wisely. Don't waste time tweaking preview renders in your 3D programme when they're going to be comped til they're unrecognisable.

    Get signoff early - if you can lock off portions of your scene that means you can render them and reduce the time it takes to preview and comp each frame. It's funny how much quicker After Effects chews through 8 layers of pre-rendered video compared to 40 layers of keyframes, colour correction and blurs.

    Use the right bit depth and format - not every project will require 32bit files. Don't waste time rendering large, slow files when smaller ones will do just as well... Also remember that uncompressed video is fast to render and work with, and can be compressed (zipped) very well when a project is finished. Also - if your delivery format is file based (eg for a specific edit system) then your editor will love you when you provide something that can be imported and played back with minimum delay. In case you're wondering: Avid 1:1 or DNxHD (.mov) for Avid systems (the codec is free from the Avid site) ProRes 422 for FCP. Premier editors will have something specific to their hardware. Make sure you ask first anyway!

    Manage your downtime - Make sure you setup a render with plenty of time to troubleshoot before you leave for the evening. We'll say no more on that one!!

    Like I said, feel free to add to these points or disagree with them!
  • Good stuff here, Dan. One thing to mention in the default setting section, in Cinema 4D, I think with AO, Blur, and other effects with similar attributes, the 'Accuracy' and 'Max Samples' settings can be changed from default to speed up render times. I think this was mentioned on GSG awhile back too. The default for 'accuracy' is 50% and 'max samples' is 128. You can effectively lower the accuracy to 10% and boost the max samples to 512 (or even higher) and produce similar results but without the increased render times. 
  • Great, great info Dan! As someone who feels that I, at times, live my life staring at renders, it's important to know all you can do to speed it up. Fantastic point mentioning "knowing what you're shooting for" before you start. That's a huge time-saver in itself. As far as settings, it's also helpful to go into the options and lower the ray depth, reflection depth, and shadow depth.

    I think this could be turned into a great article (and give folks who aren't reading the forums to see it.)

    Good Stuff!
  • @dan_hin This post is in the admin-only area. Do you want to move it to a different section (open table maybe?)

    This reminds me. Should we have a general "tips" category for the forum?
  • @conigs Yes and yes! Thanks Paul..
  • Great tips, should definitely be an article..

    I've recently found out some of this stuff the hard way, hence being in work on a Saturday, and possibly Sunday too.. :/ 

  • Oh dear James, I feel for you there! So many gotchas, so little time to check them all... Definitely going to edit this down to an article. Hope it's OK if I include you guys' input too?

  • The settings in the illumination channel as well of some materials could be messed around with so that some materials are seen by GI (If you have to use it) and some are not . I also find that baking textures and illumination is a brilliant solution specially if you have multiple cameras . You can set the Global illumination to auto-save and auto-load . You will feel the GI in the first render but the rest of the cameras could be rendered without a hassle . Baking shadows and AO Is also great specially if you have a lot of static objects . Shadows can take a lot to render

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