为克服测量端的几何约束条件,需对现有的光笔系统布置多个测量光点,这会导致测量终端结构复杂,不利于光笔系统应用于测量空间受限的场合。针对这一问题,将光场成像方法引入到光笔式测量系统中,利用光场成像原理获取光笔上光点的极平面图像(EPI),并采用旋转平行四边形算子(SPO)计算EPI中斜线的斜率,从而估计出发光点的深度信息,排除了PNP(perspective-n-points)算法的错误解,得到被测点的准确三维坐标。最后通过实验对所提方法进行了验证。所提方法仅需单目光场相机,并结合三点式光笔即可完成三维坐标值的测量,极大地简化了光笔测量系统。

Existing light pen systems are required to arrange a plurality of measuring spots to overcome the geometric constraints of a measuring terminal. This will result in a complicated measuring terminal structure. Moreover, it is disadvantageous to use the light pen system in limited measurement space. In this work, the light field imaging method is introduced into a light pen type measurement system. The epipolar plane image (EPI) of the light spot on the light pen is obtained using the light field imaging principle, and the spinning parallelogram operator (SPO) is adopted to calculate the slope of diagonal line on EPI. Subsequently, the depth information of the light-emitting point is estimated and the wrong solution of the PNP (perspective-n-points) algorithm is eliminated. Ultimately, accurate three-dimensional coordinate for the measured point are obtained. The effectiveness of the proposed method is verified by experiments. The proposed method only requires a monocular light field camera combined with three-point light pen to complete the measurement of three-dimensional coordinate value. Thus, the operation of the light pen measurement system can be greatly simplified.