Compositing CGI with Bigger Node Trees - Nuke 101: Professional Compositing and Visual Effects - page 136

Let's continue compositing the eyes.
25. Insert another Merge node after Merge7 and connect its B input to Merge6.
The lemming can see again ( FIGURE 3.54 ) . Good for him! You have been work-
ing in isolation so far and haven't seen how the lemming looks over the back-
ground. Guess what's next?
Figure 3.54. The eyes are now added to the lemming.
Placing CGI Over Live Background
Now you're going to composite the lemming tree over the background. Only after you do
that will you be able to really gauge your composite and use your complex CGI tree to its
full potential. You will then be able to make the lemming feel more like it's in the scene.
Treat this whole tree as a single element—the foreground.