Digital Lighting & Rendering, Second Edition

CHAPTER SIX: Cameras and Exposure 169

Photographs can be created that appear to have trails fading off behind a

moving object, but these are usually caused either by a camera fl ash trig-

gered at the end of the exposure or by having the subject stop moving near

the end of the exposure. If a subject was moving at a constant rate and

illuminated evenly while the frame was exposed, the motion blur would

be symmetrical and would not indicate whether the object was moving

forward or backward.

Blurring Rotations

Rapidly rotating objects—such as the blades of a fan, spinning wheels, or a

helicopter’s propeller—are some of the hardest things to accurately ...