An information processing apparatus comprising: a receiver configured to receive first information on a posture of a head of an observer and second information on a posture of a body other than the head of the observer; an image rendering processing unit configured to generate a display image corresponding to a posture of the observer based on the first information and the second information; and a calibration processing unit configured to acquire a calibration parameter; wherein the receiver receives at least a posture of the trunk of the observer as the second information, and wherein the image rendering processing unit generates a free viewpoint image that tracks a posture of the head of the observer by orienting a line-of-sight direction of the observer in a free viewpoint space based on the first information and by orienting an orientation of the body of the observer in the free viewpoint space based on the posture of the trunk of the observer obtained from the second information, wherein the image rendering processing unit, when receiving a control signal used to instruct the observer to move in the free viewpoint space as an input, determines a point after movement by recognizing, as a front direction, an orientation of the body based on the posture of the trunk of the observer obtained from the second information, wherein the image rendering processing unit performs image generation using posture information corrected by the calibration parameter, the information processing apparatus being characterised in that: the image rendering processing unit generates a free viewpoint by further arranging a predetermined image widget in a fixed position fixed on an observer trunk coordinate system and oriented based on the posture of the trunk of the observer, f and the image rendering processing unit processes the posture information of the head or the posture information of the trunk by representing it in the form of a quaternion. a receiver configured to receive first information on a posture of a head of an observer and second information on a posture of a body other than the head of the observer; an image rendering processing unit configured to generate a display image corresponding to a posture of the observer based on the first information and the second information; and a calibration processing unit configured to acquire a calibration parameter; wherein the receiver receives at least a posture of the trunk of the observer as the second information, and wherein the image rendering processing unit generates a free viewpoint image that tracks a posture of the head of the observer by orienting a line-of-sight direction of the observer in a free viewpoint space based on the first information and by orienting an orientation of the body of the observer in the free viewpoint space based on the posture of the trunk of the observer obtained from the second information, wherein the image rendering processing unit, when receiving a control signal used to instruct the observer to move in the free viewpoint space as an input, determines a point after movement by recognizing, as a front direction, an orientation of the body based on the posture of the trunk of the observer obtained from the second information, wherein the image rendering processing unit performs image generation using posture information corrected by the calibration parameter, the information processing apparatus being characterised in that: the image rendering processing unit generates a free viewpoint by further arranging a predetermined image widget in a fixed position fixed on an observer trunk coordinate system and oriented based on the posture of the trunk of the observer, f and the image rendering processing unit processes the posture information of the head or the posture information of the trunk by representing it in the form of a quaternion. the image rendering processing unit generates a free viewpoint by further arranging a predetermined image widget in a fixed position fixed on an observer trunk coordinate system and oriented based on the posture of the trunk of the observer, f and the image rendering processing unit processes the posture information of the head or the posture information of the trunk by representing it in the form of a quaternion.