Unconstrained pointing interface for natural human interaction with a display-based computer system

Apparatus which enables a user to interact with a display surface, the display surface displaying an object that represents a control that can be rotated in the image to actuate a software feature, comprising

• a hand-held pointer that includes a sensor arranged so that when the pointer is aimed at the object displayed on the display surface of the surface, from a location remote from the surface, light emanating from the object is received at the sensor, and
• circuitry connected to the hand-held pointer and configured to determine changes in the angular orientation of the pointer about an axis generally extending between the pointer and the surface and to cause rotation of the object to actuate the software feature based on determination of the rotation.

Apparatus which enables a user to interact with a passive object by pointing at selected visibly-distinct parts of a surface of the object comprising:

• a source that projects radiation onto the surface, the radiation being modulated in a pattern that permits different locations of the surface to be distinguished on the basis of radiation reflected from them, the modulated pattern comprising a vertical scan of a horizontal line preceded or followed by a horizontal scan of a vertical line,
• a hand-held pointer that includes a sensor arranged so that when the pointer is aimed at one of the visibly distinct parts of the surface, the sensor receives radiation reflected from the part, and
• circuitry connected to the sensor and configured to determine a visibly-distinct part of the surface to which the pointer is being aimed based on the modulated pattern of radiation received at the sensor.