
Preface, Motivation, and
Objective
Digital shadow generation is an important aspect of visualization and visual eects
in lm, games, simulations, engineering, and scientic applications. When we rst
published our original shadow survey paper [639] more than twenty years ago, we
had no idea that the topic of digital shadow generation would generate so much
more research. e abundance of research since the 1990s is due to several reasons:
● e diculty of resolving the shadowing problem well.
● e need to optimize the shadow algorithms for specic real-time applica-
tions. However,