In a case where a position and/or orientation of a shooting viewpoint is calculated by using information about image coordinates of markers placed in a scene, the present invention enables a user to easily determine positions of the markers so that the position and orientation can be calculated more accurately. Information about markers placed in a physical space is obtained and area information about mixing accuracy between a physical space image and a virtual space image is obtained based on the information about the markers, so that a virtual space image is generated in accordance with the obtained area information.