Multipass Compositing with Cinema 4D and After Effects 04

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Okay, so we brought everything into AE and set up our workspace. Now, what do we gain from using multipass? Let's take a look:

If you haven't already, let's take a look at the individual pre-comps that represent each light. Starting with "pass_Fill".

HOLD UP! I don't know about you, but this looks like the scene was rendered with only the fill light!
So, if I was to open the Sunlight and Ambient light, it'd look like those are the only lights in those images too!
You can also enable/disable the "Shadow", "Specular" and "Diffuse" channels. You'll notice that once you switch off "Shadow", you regain the information that was hidden BEHIND the shadow!

That's the first perk of multipass compositing. We've effectively gotten all three lights separated, at the same render time of having all three lights on at once. You can only imagine how awesome this would be if it was an animation.
Okay, so what? I could just render the light I want!

Well, yes, but if you go back to the main composition, I'll show you something interesting we can do with this.

Changing Up the Lights

Okay, head back to the main composition and select the three lights. Hit "T" to show their individual opacity controls. Now, set Ambient's opacity to 13 and Fill's to 6%.

Well well, our Fill light is now behaving a lot more like a key light. It's not competing with the Sunlight and now looks like the pieces at the front are our subject. Lowering ambient has also darkened the ground to make it less noticeable.
Wow, this is pretty nice, but let's do something more.

Select "Fill" and apply the "Photo Filter" effect. Change the Preset to "Cooling Filter (80).

As you can see, we have effectively changed the color of the Fill light without affecting the Ambient and Sunlight lighting. Once again, imagine an animation! This is very powerful. We don't have to re-render anything at all if it comes down to lighting!
Open each precomp and toy around with opacity values of Shadow, Specular and Diffuse as well as adding effects to them. Could make some funky stuff!

Okay that's pretty awesome. But what else do we have at our disposal with Multipass, other than switching lights and changing their colors?
Wow, it's hard to please you, but here's a nice long list of some things you can do in AE that will not only keep you from re-rendering, but will also help SHORTEN your render times:

  • You can render out ANYTHING to separate files, including Ambient Occlusion and Global Illumination. (When GI layer is switched off, it becomes like an ordinary non-GI render!).
  • You can texture your models (or add details to models) by using the UV pass and a plug-in like Re:Vision FX RE:Map. This is awesome for last-minute touches, or even completely re-texturing a lit model.
  • You can use Object Buffers from Cinema 4D to get luma mattes of objects, so you can composite stuff behind objects rendered in 3D.
  • You can shorten render time by applying Motion Blur in AE. By rendering "Motion Vectors" and the "ReVision ReelSmartMotionBlur" plugin to intepret that pass and apply motion blur to your final composite. It's A LOT faster than rendering motion blur from C4D.
  • You can shorten render time some more by rendering the "Depth" pass and using the built-in "Camera Blur". You can even adjust where the camera is focussing with this pass.
  • Most third-party plugins such as Turbulence FD and DPIT come with their own multi-pass options.
Well, have fun with multipass compositing. If you have any questions or would like a tutorial on a specific thing, you can use the comment section below!


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