Position detection method, position detection device, and position detection system

A position detection device configured to detect a position in an operation surface pointed by a pointing element, the position detection device comprising:

• a first processor configured to irradiate with infrared light toward the operation surface;
• and
• a second processor configured to
• obtain a first taken image calibrated with respect to the operation surface by imaging the operation surface with a first camera and configured to take an image with the infrared light,
• obtain a second taken image calibrated with respect to the operation surface by imaging the operation surface with a second camera different in imaging viewpoint from the first camera and configured to take an image with the infrared light,
• form a difference image between the first taken image and the second taken image,
• extract an area in which an amount of disparity between the first taken image and the second taken image is within a predetermined range out of the difference image as a candidate area in which an image of the pointing element is included,
• detect an area corresponding to a tip position of the pointing element from the candidate area extracted based on a shape of the pointing element;
• output, based on the area corresponding to a tip position, information representing a pointing position of the pointing element in the operation surface and whether or not the pointing element had contact with the operation surface.

A position detection system comprising:

• a first camera configured to take an image with infrared light;
• a second camera different in imaging viewpoint from the first camera and configured to take an image with infrared light;
• a detection light irradiation device configured to irradiate with the infrared light toward an operation surface;
• and
• a position detection device including
• a processor configured to
• obtain a first taken image which is obtained by imaging the operation surface with the first camera and is calibrated with respect to the operation surface,
• obtain a second taken image which is obtained by imaging the operation surface with the second camera and is calibrated with respect to the operation surface,
• form a difference image between the first taken image and the second taken image,
• extract an area in which an amount of disparity between the first taken image and the second taken image is within a predetermined range out of the difference image as a candidate area in which an image of a pointing element configured to perform an operation on the operation surface is included,
• detect an area corresponding to a tip position of the pointing element from the candidate area extracted based on a shape of the pointing element;
• output, based on the area corresponding to a tip position, information representing a pointing position of the pointing element in the operation surface and whether or not the pointing element had contact with the operation surface.