Calibration of the axis of the turntable in 4-axis laser measuring system and registration of multi-view

Since laser scanner only samples the surface of an object which is visible from a given viewpoint, in order to scan the entire object, it is necessary that the multiple views around the object are captured and aligned in a common coordinate system. Locating the center axis of a turntable precisely is essential for measuring the object which turned on the axis and the registration of multi-view. A new method is proposed to calibrate the axis of the turntable. Firstly, a ball as the calibration normal is mounted on the turntable, then measuring the surface of the calibration ball and calculating its center at different rotational angles. These centers define a circle and a plane. The normal of the plane and the center of the circle counted by geometric transform decide the orientation of the axis of the turntable. The multiple views turn around the axis and can be integrated automatically. The error of registration is about 70 μm within 80 mm rotational radius on the measuring platform whose accuracy is 50 μm. Compared with the previous methods, the new method is simple and efficient and can be used in other measuring system with a turntable.