Light pen visual measurement system is a portable coordinate measuring system that employs a light pen as a contact-assisted measurement instrument. Its benefits include good portability,wide measuring range and high precision,etc. The center coordinates of probe are recorded during the process of contact measurement;thus,the radius of the probe must be compensated. A feasible radius compensation method for unorganized point cloud is proposed by combining a light pen type measurement system. Grid processing of the point cloud is used to discover topological relationships between the points in the unorganized point cloud and obtain rectangular topological grid of local point cloud. In addition,the normal vectors of the central points of grid are obtained by fitting the NURBS curve surface interpolation based on the topological grid points. Experiments show that the obtained normal vector error angle is about 0. 5°,and when the probe radius is 2. 5 mm,the measurement error is below 0. 030 mm.
关键词
半径补偿/散乱点云/NURBS曲面插值/光笔
Key words
radius compensation/unorganized point cloud/NURBS curve surface interpolation/light pen
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