Inverse problems in computer graphics

Most traditional computations in computer graphics can be posed as forward problems: given the value of x, compute the value of some function f(x). Increasingly, however, important computer graphics computations involve inverse problems: given the value of a function f(x), compute x. Inverse problems tend to be much more difficult than forward problems, and their solution requires methods which are unfamiliar to many computer graphics practitioners. An awareness of when they arise and how they can be solved is of substantial value in a wide variety of computer graphics applications.