三维模型的空间匹配与拼接

为获得敦煌莫高窟第172窟的全景三维模型,实现文化遗产数字化保护,提出一种三维模型的空间匹配与拼接方法。首先通过基于四目立体视觉系统的复杂场景三维重建方法,获取单一场景的三维模型;然后以场景真实三维点云数据的对应图像坐标为约束条件,进行高精度特征点匹配;最后以两对同名点在相邻两场景中的空间距离应该一致为条件,保留匹配精度高的点,用于计算旋转矩阵和平移矩阵,进行三维模型间的空间拼接。实验结果表明:与传统拼接方法相比,本文的模型拼接处无明显错位现象,视觉效果更好,传统方法与本方法的匹配误差分别为0.008 2和0.001 6,拼接精度得到显著改善。     

Moving object detection method based on complementary multi resolution background models

A novel moving object detection method was proposed in order to adapt the difficulties caused by intermittent object motion, thermal and dynamic background sequences. Two groups of complementary Gaussian mixture models were used. The ghost and real static object could be classified by comparing the similarity of the edge images further. In each group, the multi resolution Gaussian mixture models were used and dual thresholds were applied in every resolution in order to get a complete object mask without much noise. The computational color model was also used to depress illustration variations and light shadows. The proposed method was verified by the public test sequences provided by the IEEE Change Detection Workshop and compared with three state-of-the-art methods. Experimental results demonstrate that the proposed method is better than others for all of the evaluation parameters in intermittent object motion sequences. Four and two in the seven evaluation parameters are better than the others in thermal and dynamic background sequences, respectively. The proposed method shows a relatively good performance, especially for the intermittent object motion sequences.     

基于空间位置特征的运动阴影检测方法

针对现有依据光学属性检测阴影的方法对不同场景通用性不强、对光照变化敏感等问题,提出一种基于空间位置特征的运动阴影检测方法.用经过标定的双目立体摄像机同时采集背景图像像对.离线获取背景图像对中各匹配点的位置对应关系.投射阴影附着在背景表面,与背景图像像对的位置对应关系相同,故可以通过比较前景图像像对各点在背景对应位置上像素值的相似程度来剔除阴影.该方法不需对环境特征及光照条件等先验知识的学习,各种复杂光照条件均不影响其检测精度.实验表明,该方法能够有效地检测出运动阴影.     

基于四目立体视觉的三维全自动建模

为保护并传承敦煌莫高窟世界文化遗产,研究基于四目立体视觉系统的三维全自动建模技术。由于提取的点云数量较大,导致自动建模过程中,点云的三角构网步骤无法顺利进行,因此着重研究点云的精简算法。将包围盒算法与点云的曲率特征相结合,提出一种点云精简算法,即改进的包围盒法。实验结果表明,该方法对点云的采样精度高于原始包围盒法,点云精简率可达93.6%,点云数据精简后三维建模效率大大提高,生成的三维模型精度较高。