Image generation apparatus, image generation method, and calibration method

1. An image generation apparatus comprising:

a marker detection block configured to scan a taken image of a plurality of markers of a fixture worn on a head of a user so as to detect a two-dimensional coordinate on the taken image of said plurality of markers;

a viewpoint position correction block configured to correct a viewpoint position of the user without use of a coordinate of a Z direction of the markers but by use of said detected two-dimensional coordinate of said plurality of markers; and

a stereoscopic image generation block configured to generate a parallax image obtained when a three-dimensional object is viewed from the corrected viewpoint position,

wherein said plurality of markers include a first marker arranged at a top section of the head of the user and

said viewpoint position correction block includes

a translation correction amount computation block configured to obtain a translation correction amount of a viewpoint position on the basis of a two-dimensional coordinate of the marker at the top section of the head, and

a viewpoint position update block configured to subtract said translation correction amount from a viewpoint position on the basis of said translation correction amount.

2. The image generation apparatus according to claim 1 , wherein

said plurality of markers further include a second marker arranged at a left-side head and a third marker arranged at a right-side head;

said viewpoint position correction block further includes a head tilt computation block configured to obtain a tilt of a head on the basis of a two-dimensional coordinate of the second marker of the left-side head and a two-dimensional coordinate of the third marker of the right-side head,

wherein the first marker, second marker, and third marker are positioned near a rotational center of the head; and

a shift amount computation block configured to obtain a shift amount of the viewpoint position on the basis of the head tilt;

said translation correction amount computation block obtains a translation correction amount of the viewpoint position on the basis of a two-dimensional coordinate of the first marker at the top section of the head and the head tilt; and

said viewpoint position update block updates the viewpoint position on the basis of said shift amount and said translation correction amount.

3. The image generation apparatus according to claim 1 , further comprising:

a calibration block configured to prompt the user to adjust the positions of the markers by moving a fixture worn on the head of the user forward and backward by making said stereoscopic image generation block generate a parallax image of a three-dimensional object for calibration so as to make the stereoscopically viewed three-dimensional object for calibration be at a standstill even if the head is moved.

4. The image generation apparatus according to claim 1 , wherein the first marker, the second marker, and the third marker are positioned on a headband worn on the head.

5. A calibration method comprising:

scanning a taken image of a plurality of markers of a fixture worn on a head of a user so as to detect a two-dimensional coordinate on the taken image of said plurality of markers;

correcting a viewpoint position of the user without use of a coordinate of a Z direction of the markers but by use of said detected two-dimensional coordinate of said plurality of markers;

generating a parallax image obtained when a three-dimensional object for calibration is viewed from the corrected viewpoint position; and

prompting the user to adjust the positions of the markers by moving the fixture worn on the head of the user forward and backward so as to make the stereoscopically viewed three-dimensional object for calibration be at a standstill even if the head is moved.

6. An image generation method comprising:

scanning a taken image of a plurality of markers of a fixture worn on a head of a user so as to detect a two-dimensional coordinate on the taken image of said plurality of markers;

correcting a viewpoint position of the user without use of a coordinate of a Z direction of the markers but by use of said detected two-dimensional coordinate of said plurality of markers; and

generating a parallax image obtained when a three-dimensional object is viewed from the corrected viewpoint position,

wherein said plurality of markers include at least a marker arranged at a top section of the head of the user and

said correcting includes

obtaining a translation correction amount of a viewpoint position on the basis of a two-dimensional coordinate of the marker at the top section of the head, and

updating a viewpoint position by subtraction said translation correction amount from the viewpoint position.