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A quick guide on Irradiance Cache Settings in Cinema 4D 63 Comments

In response to a video tutorial by Ross Gerbasi.
In this video, Rob and I go though some of the Advanced Render GI settings that will help give you cleaner renders Especially when animating.

With help from Rob Redman of PariahStudios.

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  1. Gentleman,
    that was really enlightening. On of the big C4D mysteries is solved. This interactive Tutorial thing is really great – I often was thinking about a problem in the work-flow, and bamm! Nick was asking it – scary! What I would like to know is the thing with netRender and IR Files. Woukd it be better to be pre-rendered on one machine (like Nick suggested over night) or at the final render with all clients at once?

    • The IR like any prepass has to be done on one maschine as far as i know. It’s the same with cached data for almost any module ( dynamics for example ) and also with cached data from plugins.


      • Stilgardozaurus

        Not quite. With Vray as render engine, you can calulate prepasses for all modes on multiple machines (atm, Im doing animation prepass on many computers). Also, GI type for “static animation” – when only camera is on the move can be done on many cpus. All you need is just connection tool / script (avaible from Chaos Group)

  2. When I saw the thumbnail of this video, I thought Nick shaved his head hahahaha!

  3. Thanks Nick and Rob for the insight. I did know some of this from the vray trial and error period. But all this helps.
    If you are still on R11 there is a small plugin named SmartSave that saves every render from the Live view to a file. Not updated to 11.5 so far it’s a pretty brilliant workflow tool. Can save jpeg and tiff.


  4. Hi Nick,

    As always You and Rob are the C4D champions.
    I’m new to this whole 3d concept thing, but learning in baby steps.

    My question is can you use this option if you don’t have GI and your using standard lights to map the scene?

    I’m doing one with extruded text, x3 lights for front/side and back and a slow CU of the camera moving around the object.

    thanks in advance


    • I think his will only work for GI. Simply because the switch its only available in the GI/IR tab

    • That’s really strange. You could try messing around with the x, y, z buttons on top. Click some of them off and see what happens.

    • Check your preferences under ‘Units’ (in R10). You’ve somehow managed to turn on ‘Use HPB System’.

    • Thank you sock Gradner you’re my hero,yes it’s the Use HPB System, now my rotate toll work like a dream, Big thanks to you & eli for your help Barvooo..!

  5. Nick & Rob,

    Thanks a lot for the reply, you guys rock! That makes a lot more sense now! :)

    We gotta get Rob out this way I owe him a dinner!


  6. Ross’s video helped me a lot for a project I’m currently working on for Travel Channel here in DC. I had to build a football stadium for a promo, and (not having a render farm here yet) I had to render the GI pass on a slower computer, and the final pass on a much faster one.

    Really looking forward to the lighting rigs!

  7. It is great to see these types of discussions as we are all going from beginners to, well, better beginners in our work. I am guilty of turning on GI and hoping for the best. Now I know a lot more about what the setting are for. Thanks and I can’t wait to learn more.

  8. Just some correction/clarification notes:

    that special pass is actually a error/fault check pass, so basically it is checking for any drastic/dramatic changes, if there isn’t then it will render with existing pass only, if there is it will compensate.

    If you lock then it uses only the stored cache and can produce really nasty results if you say added an object.

  9. Allrighty some nifty stuff.
    To make a few things clear (for me mostly :p);
    if I were to make an animation with the auto load on, and I would make some changes in let’s say the texture pattern and it’s color the re-render would take up to 90% less time and still look correct (what about the reflection of color onto it’s enviroment, would that still be valid) ?

    And rendering it with a different anti-aliasing or greater resolution would that work ?

    Thanks for the info :)

    • You have to turn on the “shadow caster” check box. Click on your light the you want to make shadows with. Go to the details tab and that’s where you will find the shadow caster box.

  10. One thing about autoload is that it can actually make things slower in certain circumstances. I made a scene with 200 bouncing, glowing orbs using using the IR setting. For whatever reason, using auto load cache dramatically slowed render times.

    I think it’s because all the primary light was coming from the glowing orbs and their reflections so the GI had to be re-cached every frame. The resulting cached file was over 100MBs. Turning off auto load made things over 400% faster.

  11. Hey Guys,

    Thanks for this tutorial.
    I’d been scratching my head with the GI cache settings.

    This is also particularly handy when using online render farms, where you have to supple a gi cache file separately to your project files.

    Also I would love to share information with folks on what things I’ve learnt or get stuck on, what’s the best software to records your screen and camera simultaneously with?


  12. jbizzle

    this great to have this broken down

    trying to get a workable recipe for GI in animations. the default is like 11 prepasses – is there any good wisdom available as to what settings we can tweak to get render times down.

    also, is shadow flicker a solved issue?

  13. previously i was 3ds max user, but now i am learning c4d and found it best tool for motion graphics, nick you are helping me a lot and this GI option really saves my life. thank nick.

    • Dubya

      What are you rendering? Terrorist training videos? Planes flying into buildings?

  14. clouder

    I watched one of your tutorials and found it amazing,solved some of my puzzles about C4D,thank you again

  15. Awsome and cool tutorial!!!
    I would like to ask how would someone make a image that is self illumnated! Like a bunch of balls that has glow in side them but no light or sky!? Could you help me?

  16. Man, the 1st thing I did was looking for the alternative + sign when stepping over from 3DsMax. Save incremental saved my life a few times :)

    Studio setup sounds pretty promising.
    Maybe you guys can figure out what the guidelines for the ‘preparing’ stage are. Still kinda black box to me. May grab my cam and post a request for it soon.

    Thnx .. keep rockin’

  17. There is possible a mistake with the concept of using cached gi and changing objects colors

    Make a cornel box setup with say a sphere inside, make the sphere red and have it on high gi generation say 500 % so you can see the red spill on the floor. Now render with save on for the gi
    If you render this using the cached gi but change the sphere color to green you will see that the gi spill is still red

  18. Great tutorial guys, but still a bit confused.

    So if i’ve got lock on all i can do is change the camera position.

    If i’ve got lock off but autoload on, all i can change is the above plus, object and light colours, textures.

    If i need to adjust the position of geo, add new geo, adjust light position or intensity then i have to flush the cache or turn off auto load (which would cause the cache to be rewritten anyways).

    Is that essentially it?
    Great tho speeds things up a treat

  19. Hi! first, congratulations! greyscalegorilla and pariah are great! this is my first comment in the blog ๐Ÿ˜€

    I have a very big problem with the GI, and i think that iยดm making something stupid wrong :(.

    when i render a animation a lot of stranger shadows appears in my scene. Do you understand me? :(

    • Sounds like you may be using “Camera Animation” settings. Try using the “Full Animation” and your weird shadows should go away.

    • lot of thank Mr. Gorilla! but… it will take a lot of time! isnยดt it? can i make a pass only for the GI? cause, if i make a render only for GI when i try to render with the cache calculated weird shadows appears again…

      PD: excuse me for my english… iยดm spanish :S

  20. I came upon this article while at work test rendering and tweaking settings for a final render to run over the holiday weekend. I must say checking the Auto Load and Lock boxes have greatly and I mean greatly increased my render times. Nick and Rob, I could hug you guys. In fact, if I am ever in the same room as you guys, watch out. These arms are acoming!

  21. Alflud

    A little bit late chipping in here but I thought this was worth sharing … when you’ve finally got what you think is a good GI solution that you would like to cache – to speed up the caching you can go into your render setting and set your resolution to half what your final resolution is going to be.

    E.G. – If your shooting for 1280px x 720px then go and set a 640px x 360px resolution. Check ON the ‘prepass only’ checkbox in the Irradiance Cache File tab and check ON ‘auto save’. Leave ‘auto load’ checked OFF and hit render. No need to save any images or movies at this point.

    When this prepass is saved (into that ‘illum’ file in your project folder) check ON both ‘autoload’ and ‘lock’ and then go back into your render settings output tab and change your resolution back to full size. Choose a save format and render out your scene.

    This might not always produce the best results – it totally depends on what you are doing – but for MOST scenes there will be no noticeable difference in the final output and it saves a LOT of time during the caching process. Check it out ๐Ÿ˜‰

    • CW2011

      Great tip- I am going to give this a go on the project I am working on now-

      Quick question, and forgive my “noob-ness”… I have a scene where just the camera moves, BUT I animated the sun to rise throughout as the camera flies through- do I understand correctly that locking the cache can’t be done, since my light source is changing throughout? It makes sense to me that that is the case, but wanted to confirm- Thanks for the tip!

    • Alflud

      Well no – not really. This applies to all kinds of animation. It just requires that nothing changes between caching the half resolution GI and then rendering the full resolution pass. Since you have the sun rising and obviously the lighting is changing constantly throughout the scene you’ll have to select ‘Full Animation’ in your render settings.

      Do this, then set your render output to half what it’s going to be and cache the GI – it will take a lot less time than caching a full-rez solution. Set your frame range to manual and render off a second or two so you can confirm that the half resolution GI pass is suiting the full resolution final. If it is – and it very often does – then it’s all go. Needless to say, the better your GI settings the better the result but anyway, after that unlock the GI cache and render from where you left off – if you haven’t saved the file under a different name Cinema will add to the cache that’s already there – although having said that this is what’s supposed to happen. I’ve found that this can be funny sometimes and Cinema actually re-does the frames that are already there. It’s supposed to detect if anything in the scene has changed since the last caching but I think it’s a bit hit and miss.

      One more thing ….. ain’t nothin’ to forgive buddy – we were all n00bs at one stage or another ๐Ÿ˜‰

      • I found this series of comments very helpful several months ago when I was rendering this –

        Now I’m back on another project that’s full GI (with a moving sun like CW2011) 3600 frames long and 3600px wide. So I’m looking to optimize my pre-pass time as much as possible. Apparently I can adjust my frame step options too, so no only will my prepass be 1/2 the resolution, but also only ever other frame will be rendered. TIme for some tests…

        Thanks again Alfud

    • andyweak

      This method worked well on my 1920×1080 render cutting my render time in half although it was still a hundred hour render. One thing to remember is to UNCHECK ‘prepass only’ after you cache your GI files. I will probably use this technique often on my renders. Thanks for the tip Alflud!


  22. keenan

    can you do a video on your render settings because yours is really fast

  23. Have you ever thought about adding a little bit more than just your articles? I mean, what you say is important and all. But think about if you added some great graphics or videos to give your posts more, “pop”! Your content is excellent but with images and video clips, this blog could definitely be one of the most beneficial in its niche. Awesome blog!

  24. Awesome learning curve from these tut’s Nick ๐Ÿ˜‰
    As you can guess though there is never enough info and there is always someone like me asking more questions such as:
    If I have a project with say 650 frames which needs a final render with IR + QMC (Full Animation) but I am doing a GI pre-pass 1st to speed up the final render so I am cutting my resolution by half, frame step to 2. This is all good but on my GI pre-pass do I need Anti-Aliasing enabled or can I turn it off as AI is just for detail right?
    Thanks for any help and keep on truckin ๐Ÿ˜‰

  25. Samuel Hall

    This was incredibly helpful! I’m working on rendering a hugely complex CG set wherein only the camera is moving so it benefits greatly from locking the GI cache.

    Can’t thank you enough for posting this! Seriously, you saved my ass.


  26. Stav Havivi

    Hey GSG,
    May I suggest A new tutorial dealing exclusively with GI animation rendering? IR prepass, chach pass…

    I have to say this one is a bit too cluttered (no offence, to you or Rob).


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Comment Rules

This is a friendly community. Please treat everyone with respect. We don't all have to agree, but we do have to be nice. Criticism is fine, but rude comments and name calling will be deleted. Use your real name and don't be spammy. Thanks for adding to the conversation.