Render Time


I have a scene that I’ve made for an animation. The objects in the scene are not very complex at all, but most of the materials applied to them are at least a little reflective. The scene is lit by nine volumetric lights, eight of which are the product of an array. Radiosity is not turned on and there is no dispersion settings applied to any of the reflective or transparent materials, though I would like to, if I can, for the final render. But for now, rendering a single frame of the scene at 480 X 360, 72 dpi, takes about fifteen minutes. Turning off the reflections cuts it down to about eleven minutes.

Are there any ideas to cut down the render time a good deal more? I’m open to anything right now.




The volumetric lights are killing you. Do you really need so many? If possible do the volumetric effects in post with a plugin like Trapcode Shine.


Trapcode Shine eh? Can you tell me more about it, or give a link? Sounds uber useful for something I’ll be working on in the near future…



Here you go: don’t actually have the plug-in because I haven’t needed it yet, but I’ve got it on my watch list for when the occasion arises.


Great plug-in and easy to use - one of those one trick ponies that really does it’s thing.



volumetric light are as adam says killing you could you also used visible lights for faster results than vol lights at least. :shrug:


Sounds like you’ve made the typical newbie mistakes. When you get into cg the first thing you need to learn is how to troubleshoot a scene. You should have experimented with one volumetric light, and learned as much as you could about it first, before adding an array of them. And when you encounter a problem you need to disect the scene of it’s individual parts and test each one alone before adding them all together.


I have objects close to the lights and I don’t want the visible light to just pass through them. I’ll be looking into Trapcode, though. Thanks Adam.



Very Important Tip: You will get far better and much faster render results if you change the default shadow setting from 250 to 750. A low shadow setting causes more streaking in the volumetric haze and considerable slows down the render, by as much as five times! Start with a shadow setting of 750x750 and tweak the sample rate to adjust the cleanness (streakiness) of the haze.

Interesting. I’m sure that’ll help a lot then.



Here is a technique I’ve used many times in the past for volumetric lights in productions:

Duplicate your scene and change everything in it to black. Switch off all your other lights so that the only ones on are the volumetric ones. Set their beams to white.

Render out your sequence. Because of the lack of other lights and colour, it renders much faster.

Render out the sequence from the scene into which the volumetric lights need to be placed.

Take these two into a compositing program and use a blending mode like screen or dodge to place the volumetric light into the rendered scene.

Voila! :slight_smile:


You say lot’s of reflections ? Then check your antialiasing settings (if you use Best). Check if you can get away with less samples…


fantastic tip…:thumbsup:
will definitely give that a try out…cheers.


Yeah that is a really nice tip. I’ve been using C4D for mostly large format, high resolution still images, so I’ve never really minded single renders that take hours. Aside from some mediocre school projects, this would be my first significant animation attempt. I’m trying to put some old habits away and work on ways to manage things for an animation.

All of your comments are very helpful.
Thank you all very much!



Another advantage, apart from speed, in the technique I suggested is that you have complete control over the colour of the lights in your compositing program :slight_smile: Very useful indeed!


To speed up volumetric lights you can increase the sample distance parameter in the lights visibility section. However if you increase it too high the quality will reduce.



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