Compositing CGI with Bigger Node Trees - Nuke 101: Professional Compositing and Visual Effects - page 142

You can see here that the background is only getting darker in the area where the
shadow should be dropping. You can turn off the Mask input to see its effect.
5. Uncheck the check box next to the Mask property's drop-down menu to turn off
the mask channel.
This is the difference between having the mask channel and not having it. This
ability to limit the area an effect or a node works in is one of the really strong
points in Nuke.
6. Check the check box next to the Mask property's drop-down menu to turn on the
mask channel.
This almost concludes this chapter. But one last thing.
You can now look at this composite and see the result of all the work you did.
You have a lemming over a background. Those with more experienced eyes may
notice that there is a lot more work to do to get this lemming to look as if he
was shot with the same camera and in the same location as the background im-
age—but that's more of a compositing lesson than a Nuke lesson.
What's important now, though, is that you have access to every building block of
what makes up the way the lemming looks. Having the separate passes easily ac-
cessible means your work will be easier from here on out.
For now, though, leave this composite here. Hopefully, it helped teach you the
fundamental building blocks of channel use and how to manipulate a bigger tree
( FIGURE 3.62 ) .
Figure 3.62. Your final tree should look like this.