Abstract: When an operator operates a pointing device, a direction computing section computes a movement vector from an image photographed by an image sensor, and when the movement vector is larger than a threshold, a direction correcting section determines the movement vector as invalid based on the recognition that the movement vector was caused by an abrupt change in the illumination or other conditions, and outputs only movement vectors that are smaller than the threshold to a coordinate position updating section.

Abstract: An optical-type position and posture detecting device includes at least two light sources. The two light sources are disposed at a predetermined distance. The two light sources are alternately switched over. A light receiving element receives light from each of light sources and detects at least two-dimensional angle with regard to each light source. The posture and position of the light receiving element is calculated on the basis of the predetermined distance and two-dimensional angles. An angle detecting device includes a photodetector having at least two receiving portions. At least one light intercepting plate disposed between two light receiving portions, vertically with regard to light receiving portions. The incident angle of light from a light source falling the photodetector is calculated based on the quantities of light received on each of light receiving portions. The light intercepting plate may be made of a light absorbing material or may be made in the form of a two-surface mirror.