Patent ID: 7613356

Claim:
A position and orientation detection method of detecting a position and orientation of an image sensing apparatus that senses real space, the method comprising: an orientation change detection step of detecting an extent of change in orientation of the image sensing apparatus; a first image coordinates computation step of obtaining coordinates in an image of indicators included in a real space image sensed by the image sensing apparatus; a position and orientation estimation step of estimating a present position and orientation of the image sensing apparatus based on position and orientation of the image sensing apparatus obtained previously and the extent of change in orientation of the image sensing apparatus obtained in the orientation change detection step; a second image coordinates computation step of obtaining coordinates of indicators in a sensed image display screen of the image sensing apparatus at the position and orientation obtained in the position and orientation estimation step; an identification step of identifying corresponding pairs of indicators from among the indicators obtained in the first and second image coordinates computation step; a counting step of counting a number of the pairs of indicators identified in the identification step; a selection step of selecting a first correction method if the number of the identified pairs of indicators is more than or equal to a predetermined number, and selecting a second correction method if the number of the identified pairs of indicators is less than the predetermined number; a position and orientation correction step of correcting the position and orientation estimated in the position and orientation estimation step using the correction method selected in the selection step.