A 3D detection system with 48-point light sources was designed to improve the accuracy of 3D surface reconstruction based on photometric stereo.All the point light sources were mounted on the inner surface of a hemisphere.The locations of light sources were calibrated using glossy black ball.In one sequence of illumination,the surface under test was illuminated by each point light source in turn.A camera mounted on the vertex of the hemisphere captured the surface image under illumination of each light source,and 48 images of the same area under illumination of different angle lightings were captured.High resolution 3D surface data of the surface under test were obtained by gradient calculation and 3D reconstruction with 48 images.Results of experiments showed that surface defects of metals with size of 0.1 mm were detected by the designed system.%为了提高基于光度立体法的表面三维重构的精度,设计了48个点光源的三维检测系统,所有光源安装在一半球体的内表面上.采用高光黑球法对光源位置进行标定,在1个照明序列内,48个光源依次对被测表面进行照明,安装在半球体顶点的相机拍摄每个光源照明后的表面图像,可得到48幅不同角度照明下的被测表面图像.对48幅图像进行梯度计算、三维重构后,可得到高精度的表面三维数据.实验结果表明,所设计的系统可检测尺寸为0.1 mm级的金属表面三维缺陷.
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