Importance
Ordering for
Real-Time
Depth of
Field
Paul
Fearing
Appeared in Proceedings of the Third International Conference on Computer
Science (pp. 372-380; Hong Kong)
TR-96-06
This paper introduces a new way of computing DOF that is particularly effective for sequences of related frames (animations). It computes the most noticeable DOF effects first, and works on areas of lesser importance only if there is enough time. Areas that do not change between frames are not computed.
All pixels in the image are assigned an importance value. This importance gives priority to pixels that have recently changed in color, depth, or degree of focus. Changes originate from object and light animation, or from variation in the camera's position or focus.
Image pixels are then recomputed in order of importance. At any point, the computation can be interrupted and the results displayed. Varying the interruption point allows a smooth tradeoff between image accuracy and result speed. If enough time is provided, the algorithm generates the exact solution.
Practically, this algorithm avoids the continual recomputing of large numbers of unchanging pixels. This can provide order-of-magnitude speedups in many common animation situations. This increase in speed brings DOF effects into the realm of real-time graphics.