[Figure 46] Final comp of the beach ball over beach background.

Combining the Beach Ball Layers
The grain can now be added to the beach ball element. If the grain is adjusted to match the background element closely, this should be a straightforward add process. Once again, if the grain looks incorrect, adjust the values to help the ball blend in with the background. With the grain applied to the beach ball, the result can be placed over the background. Because the background has already been darkened using the shadow mattes, the beach ball should fit nicely over its shadow. The last step in this example is the application of the edge blending. In the photographic reproduction of most scenes, there is a certain amount of interaction between the elements. It is noticeable particularly at the edges of objects, in which a small amount of the background appears to bleed into the edge of the foreground element. This can be simulated with the edge matte created earlier. In this example, the beach ball element is blurred through the edge matte. This creates a semi-transparent thin edge to the ball, allowing pixels from the background to bleed through slightly. This is a delicate operation, and keeping the edge matte thin, as well as using a reasonable blur amount, will prevent the edge of the ball from appearing transparent (see Figure 46). An alternate method for blending the edge with the background begins with putting the background inside the edge matte after the beach ball shadow has been applied to the background. This provides the beach ball’s edge, but with the background inside of it. This new element can then be blurred and carefully added to the beach ball after it has been placed over the background. This essentially accomplishes the same thing as blurring through the matte but with different operators. There is rarely a single solution to a compositing challenge, and experimenting with different approaches often helps the compositor develop new tricks and a stronger understanding of the discipline.

Each of these finishing touches can add a great deal to a shot, but many may also go unnoticed. When adding these touches to a shot, carefully evaluate the time involved in their creation versus the ultimate visual payoff. For instance, you might spend an entire day adding just the right specular glint to a character’s fingernail for two frames of a shot. If no one notices it, then it hasn’t really improved the shot, and the time could have been better spent making progress on other shots. There is a fine line between appropriate attention to detail and excessive tweaking. Until you’ve gained the experience to confidently make this call on your own, it is vital to solicit the opinions of peers and supervisors to help develop this sensibility. There are many valuable concepts presented in this chapter, but it only begins to scratch the surface of compositing as an art and a profession. With the ease of shooting digital video and capturing it on a computer, opportunities to practice are readily available. Observation and reference remain the most valuable tools, because compositing is ultimately understanding how 2D layers come together to simulate a 3D world.

Author David Parrish (left), series editor Kyle Clark (center) and series editor Mike Ford (right).

David Parrish went straight to work for Industrial Light & Magic after earning his master's degree from Texas A&M University. During the five years that followed, he worked on several major films, including Dragonheart, Return of the Jedi: Special Edition, Jurassic Park: The Lost World, Star Wars: Episode I — The Phantom Menace, Deep Blue Sea, Galaxy Quest and The Perfect Storm. After five years with ILM and a short stay with a startup company, he was hired by Sony Pictures Imageworks to work on Harry Potter and the Sorcerer's Stone.

Series editor Kyle Clark is a lead animator at Microsoft's Digital Anvil Studios and co-founder of Animation Foundation. He majored in film, video and computer animation at USC and has since worked on a number of feature, commercial and game projects. He has also taught at various schools, including San Francisco Academy of Art College, San Francisco State University, UCLA School of Design and Texas A&M University.

Michael Ford, series editor, is a senior technical animator at Sony Pictures Imageworks and co-founder of Animation Foundation. A graduate of UCLA’s School of Design, he has since worked on numerous feature and commercial projects at ILM, Centropolis FX and Digital Magic. He has lectured at the UCLA School of Design, USC, DeAnza College and San Francisco Academy of Art College.