Compositing CGI with Bigger Node Trees - Nuke 101: Professional Compositing and Visual Effects - page 108

You can see that the result is already not bad. The good thing is that the lemming
is tracked in place. The lemming is missing one frame, but don't worryabout that
as you are just using this as an exercise. What you should worry about, however,
is the lemming looking as if it doesn't belong in the scene. Its color is all wrong
for the background and it simply doesn't feel as if the lemming is there, shot on
location, which is what compositing magic is all about.
7. Quit Framecycler or click the Stop button in the Viewer.
8. You no longer need the slap comp, so select Merge1 and delete it.
Building the Beauty Pass
Nextyou'regoingtotakeallthepassesandstartbuildingthebeautypassasitwasbuiltin
the 3D renderer. When you're finished doing that, you'll have full access to all the build-
ingblocksoftheimage,whichmeansyou'llbeabletoeasilychangesomethings,suchas
the color and brightness of passes, to make the comp look better.
The passes will be built like this: First you combine the Lgt and Col passes using a Merge
node's multiply operation. Then you Merge with a plus operation in this order: the Inc,
Ind, and Spc passes. You then subtract the shadow pass with a Merge node's operation.
This is the way this image was created in the 3D software that created it, so this is how
you recombine them in Nuke.
There are two ways to work with channel sets in Nuke. The first is by working down the
pipe, and the second is by splitting the tree. First, you will look at how to work down the
pipe and then move on to working with a split tree.