由于激光扫描一次只能测量给定视角可见的物体表面,若测量物体全方位的形状,必须通过旋转,从多个视角测量物体,并将多视数据拼合于同一坐标系。精确标定转台的中心轴线是旋转测量和多视拼合的关键。提出了一种标定转台中心轴线的新方法,该方法将一个标定球固定于转台上,通过旋转,测量不同位置的标定球,计算不同位置的球心及其所在平面的法矢,再利用几何变换计算球心所在圆的圆心,从而精确标定出转轴的方位,实现了多视测量数据在线自动拼合,提高了数据拼合的精度。对于精度为50 μm的测量机,在半径80 mm的旋转范围内,拼合误差约为70 μm。与以前的方法相比,设计的转轴标定方法简单、高效,在其他安装转台的测量系统中同样适用。

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 which 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.