Marker image processing system

An image processing system in which a marker having a plane indicator is used to recognize the position and posture of a camera relative to the marker, one three-dimensional indicator that has a predetermined height being located at a position predetermined relative to the plane indicator on the marker, comprising:

• a first estimation means that compares the location of the plane indicator extracted by the image of the camera with the predetermined location of the plane indicator to thereby estimate the position and posture of the camera relative to the marker;
• a second estimation means that estimates, based on the location and height of the three-dimensional indicator as well as the position of the camera relative to the marker estimated by the first estimation means, the center positions of an upper face and a lower face of the three-dimensional indicator on the image of the camera;
• a detection means that detects, based on the image of the camera, the center position of the upper face of the three-dimensional indicator;
• a determination means that compares the center position of the upper face of the three-dimensional indicator estimated by the second estimation means with the center position of the upper face of the three-dimensional indicator detected by the detection means based on a each of vectors from the center position of the lower face of the three-dimensional indicator estimated by the second estimation means as an origin to each of the center positions of the upper face of the three-dimensional indicator to determine, when the error has a value equal to or higher than a predetermined value, that the posture of the camera relative to the marker estimated by the first estimation means is false;
• and
• a calculation means by which, when the false determination is made by the determination means, signs of a visual-line angle around an X axis and a visual-line angle around a Y axis of the camera based on the posture estimated by the first estimation means are inverted respectively so that the posture of the camera relative to the marker estimated by the first estimation means is correct and are subjected to a rotational transformation to thereby recalculate the posture of the camera relative to the marker, wherein:
• the X axis and the Y axis respectively represent coordinate axes orthogonal to each other on the marker plane at a three-dimensional coordinate having one point on the marker as an origin.