In the three-dimensional (3D) contour measurement, the phase shift profilometry (PSP) method is the most widely used one. However, the measurement speed of PSP is very low because of the multiple projections. In order to improve the measurement speed, color grating stripes are used for measurement in this paper. During the measurement, only one color sinusoidal fringe is projected on the measured object. Therefore, the measurement speed is greatly improved. Since there is coupling or interference phenomenon between the adjacent color grating stripes, a color correction method is used to improve the measurement results. A method for correcting nonlinear error of measurement system is proposed in this paper, and the sinusoidal property of acquired image after correction is better than that before correction. Experimental results show that with these correction methods, the measurement errors can be reduced. Therefore, it can support a good foundation for the high-precision 3D reconstruction.

A calibration method for the five essential parameters is proposed. Using the calibration results, the three dimensional (3D) reconstruction can be performed directly. The five essential parameters include the distance between the camera and the projector, the distance between the reference plane and the camera, the fundamental frequency of the fringe pattern, the scale factor from the image coordinates to the world coordinate system in X axis direction and that in Y axis direction. The proposed calibration method is implemented and tested in our 3D reconstruction system. The mean calibration error is found to be 0.0215 mm over a volume of 400 mm (H)×300 mm (V)×500 mm (D). The proposed calibration method is accurate and useful for the 3D reconstruction system.

针对近景摄影测量中对编码标记点进行精确定位并对具有唯一编码值的编码标记点进行解码识别的要求，提出了一种环状编码标记点自动检测和识别算法。该算法首先对图像进行canny边缘检测，通过一系列限制条件和计算封闭轮廓质心来过滤噪声和非编码标记点。然后，采用最小二乘椭圆拟合进行编码标记点定位，结合椭圆拟合误差判断分割编码标记点轮廓并进行填充。最后，提出一种将局部同心椭圆变换为平行直线的ALPC (Affine LOG Polar Coordinate)变换，对分割出的编码标记点进行ALPC变换，利用变换后的图像特征进行解码。实验结果表明，利用本文算法对于编码标记点的定位可以达到亚像素级别；且当相机光轴与编码标记点法线夹角小于60°时平均识别准确率能达到98.8%，当夹角达到70°时识别准确率仍然能达到90.2%；在复杂背景下的识别准确率能够达到96.46%。

为了实现不同颜色、不同光照条件下物体的高精度三维测量，对多频率三维测量中的相位叠加、相位编码以及全局解相方法进行了研究。首先，选取三种不同频率的正弦波形，经过 3~8步相移，向物体投射光信息，并通过相位叠加，获得等效频率的相位信息。接着，利用已经获得的等效相位信息，对三种不同频率的相位信息进行编码。然后，在相位编码的基础之上，通过全局解相方法，获得全局相位信息，进而获得高精度物体三维坐标。最后，介绍了精度验证方法及其与传统格雷码三维测量方法的精度对比。实验结果表明: 格雷码的三维测量精度为±0.04 mm；多频率三维测量精度为 ±0.02 mm。多频率方法不但测量精度高，并且可以弥补格雷码方法无法实现不同光照条件下的三维测量难题，具有更广泛的适用性。