多自由度双目立体视觉系统可以解决传统双目立体视觉视场区域小的问题。避免双目摄像机每转动一个角度都需要重新标定外参数, 提出了一种基于转轴参数的标定方法。只需标定出初始位置时双目摄像机的内外参数, 使摄像机绕转轴旋转, 根据单应性原理测量摄像机与标定模板的位姿关系, 确定转轴方向矢量与轴上点坐标。最终利用Rodrigues旋转矩阵确定旋转已知角度后双目摄像机的外参数, 实现多自由度双目系统的标定。实验结果表明, 提出的方法能准确测量转轴参数, 完成多自由度双目立体视觉系统的快速标定, 提高系统的工作效率。

为有效提高三光带激光三维人脸扫描仪的性能，提出一种基于辅助窗平面的优化方法。通过在测量区域的前沿安装窗平面，不但可有效定位扫描系统的测量区域，保证获得完整的待测人脸三维点云模型，最主要的是借助窗平面左右竖直边框散射的辅助光带可实现对三条测量光带的快速、可靠分组，有效解决了原扫描系统要求的在首帧图像中必须同时包含三条测量光带的问题。实验结果表明所提方法算法简单、鲁棒性强，使得扫描测量过程更加易于操控。

在使用结构光进行三维重建与测量的过程中, 为避免物体表面的反射光产生噪声干扰, 导致错误的三维测量结果, 提出一种在三维扫描系统中用于防止反射光干扰的投影补偿算法, 利用高空间频率投影图案的概念, 对场景中被反射光干扰的点进行去噪。再用统计分析算法对点云数据进行去噪、反馈并得到投影图的掩码图案, 经过多次投影补偿后得到场景的三维点云数据。通过自行搭建的格雷码结构光三维扫描系统对实物场景进行扫描重建。实验表明该系统对于反射光的干扰具有较好的鲁棒性, 且投影数量减少, 验证了算法及系统的可行性。

针对常用特征点匹配算法在低对比度图像中存在特征点少、匹配精度低的问题, 将图像自相似性用于图像特征点提取, 并改进特征点匹配过程, 提出了自相似性与改进归一化互相关相结合的方法。该方法首先根据像素点自对称值提取出图像特征点, 然后通过特征点的尺度信息构建自适应相关窗口来改进互相关匹配, 最后由阈值筛选和随机抽样一致性算法优化匹配结果, 从而完成低对比度图像特征点的提取和匹配。实验结果表明, 该方法在匹配低对比度图像特征点时相比常用算法具有较高的效率, 且对图像尺度和旋转变换具有较强的鲁棒性。

Noise reduction is one of the most exciting problems in electronic speckle pattern interferometry. We present a homomorphic partial differential equation filtering method for interferometry fringe patterns. The diffusion speed of the equation is determined based on the fringe density. We test the new method on the computer-simulated fringe pattern and experimentally obtain the fringe pattern, and evaluate its filtering performance. The qualitative and quantitative analysis shows that this technique can filter off the additive and multiplicative noise of the fringe patterns effectively, and avoid blurring high-density fringe. It is more capable of improving the quality of fringe patterns than the classical filtering methods.

Traditional speckle fringe patterns by electronic speckle pattern interferometry (ESPI) are inherently noisy and of limited visibility, so denoising is the key problem in ESPI. We present the variational denoising method for ESPI. This method transforms the image denosing to minimizing an appropriate penalized energy function and solving a partial differential equation. We test the proposed method on computer-simulated and experimental speckle correlation fringes, respectively. The results show that this technique is capable of significantly improving the quality of fringe patterns. It works well as a pre-processing for the fringe patterns by ESPI.