Camera calibration which is robust against noise factors such as variation in environmental lighting and obstructions is realized. Light-emitting markers, whose on/off states can be controlled, are arrayed in a matrix on a reference panel on which an object is placed. The light-emitting markers blink in accordance with respective switching patterns in synchronism with the frame of continuous imaging of a camera. A three-dimensional measuring instrument determines the time-varying bright-and-dark pattern of a blinking point from the image of each frame and identifies, on the basis of the pattern, to which light-emitting marker each point corresponds. By reference to the identification results, camera calibration is performed, and a coordinate transformation parameter is computed.