HIGH ACCURACY CALIBRATION FOR 3D SCANNING AND MEASURING SYSTEMS

摘要

A system for high accuracy calibration of a scanning system, which provides an object for calibration of a known geometry, such as a plane or a sphere. Upon that object is marked a pattern of points or geometric shapes, such as a set of equilateral triangles or their vertices. A set of computer programmed elements process photographic images of the object (containing a depiction of the pattern of geometric objects) and scanned images of the object to calibrate to high precision parameters, including a focal point relationship value for scanning systems which use a camera as an image collector (which describes the relationships between the focal point of the lens and the light/image collection device of the camera), a set of values to correct for distortion of the lens, the relative distance between the image collector and the scanner light source and also an initial angle to determine light position scanning. The known geometric constraints of the object allow the location of the object to be determined by photographic images. By scanning the object and computing 3D X,Y,Z coordinates for those points against a constraint that the X,Y,Z coordinates fit onto the surface of the object, the system calibrates parameters pertaining to the relative distances between the image collector and light source, an initial angle of rotation for systems which employ movable light sources and other parameters. The system is applied to multiple camera scanning systems to calibrate rotation matrices and translation vectors which facilitate the joining of the scanned data. The system further facilitates the design of flexible and movable scanning systems, such as portable scanners.