Footnotes:

1 An owl (like many nocturnal animals) must move its entire head look in a new direction. Its light-gathering retinas are so large that there is insufficient room in the eye sockets for muscles to move the eyes.

2 A mistake made during an active vision maneuver means the vision system may be temporarily aimed in the wrong direction, a condition that usually can be detected by other levels of reasoning and is recoverable.

3 At print time, the PC microprocessor has been recently upgraded to a 200 MHz Cyrix chip.

4 The use of this terminology is not completely consistent in the literature. Voice recognition is sometimes used to describe recognition of words, especially in product marketing, e.g. IBM's VoiceType Dictation(tm).

5 Motion detection during camera motion is possible, but too computationally intense for this application.

6 The sensor mount for this project was carefully designed with vibration-absorbing materials isolating the camera, frame, and microphones to eliminate any direct vibration. However, motor sound from the Canon VC-C1 motors does reach the microphones through the air. During high-speed camera motion, the noise can interfere with sound localization. Note that the Canon VC-C1 was the quietest of several pan-tilt units considered for this project, but quieter products now exist. Attempts to characterize the motor noise revealed that it was quite broadband and would resist most attempts at removal through simple filtering.