基于图分割与Hausdorff距离的多分辨率影像匹配

针对具有复杂场景的航拍图像提出了一种基于图分割理论与Hausdorff距离的多分辨率影像匹配方法。在高斯金字塔图像模型中,低分辨率的图像通过图分割方法,充分考虑图像中的局部和全局的信息,提取到稳定和完整的图像区域边界,并以区域边界作为待匹配的曲线。再通过计算曲线的统计特性作为图像间待匹配特征,并由信号相关的度量方法粗估计出图像间全局仿射变换参数。利用粗估计的参数在高分辨率层次上进一步通过基于Hausdorff距离的匹配方法搜索到精确的变换参数。实验结果表明,该方法在较大变形和强噪音干扰的情况下对复杂场景的图像也能有效地完成匹配。     

一种新的抗几何攻击的图像认证算法

提高图像抗几何攻击的能力是当前图像认证算法待解决的重点之一。提出了一种抗几何攻击的图像认证算法,该算法利用图像边界的Radon投影变换来实现图像几何失真的矫正,根据感知hash方法提取图像的特征点,并通过修正Hausdorff距离来实现对图像的认证。实验表明,该算法可以抵抗一定程度的JPEG压缩、叠加噪声等图像处理,也能抵抗旋转、缩放等几何变换,并且对于恶意篡改具有较好的敏感性。     

基于Hausdorff距离图象配准方法研究

图象配准是图象融合的一个重要步骤，为此提出了一种自动图象配准算法，该算法从两幅待配准的图象中分别抽取特征点，然后选用Hausdorff距离对两特征点集进行匹配，得到点集间的仿射变换，从而实现图象的自动配准，此算法以特征点而不是物体边缘计算仿射变换，大大降低了计算Hausdorff距离的运算量；同时，基于Hausdorff距离的图象匹配只需要点集之间的对应，而无须点与点的对应，因而可以使用于存在较大物体形变的情况，即完成两幅差异较大图象的配准，实验结果证明了算法的有效性。     

基于分支特征点的导航用实时图像匹配算法

为了满足景象匹配辅助导航系统需要同时获取飞行器位置和航向偏差的需要, 提出了一种基于分支特征点提取的图像匹配算法. 传统的图像匹配算法需要全局搜索匹配特征点, 耗时巨大, 而只提取分支特征点来匹配能满足导航系统实时性的要求. 在匹配算法方面, 提出了采用加权 Hausdorff 距离算法来进行匹配. 同时, 根据分支特征点的特性, 推导了相应的权值求解公式. 仿真结果表明, 本文提出的匹配算法耗时较短, 能满足导航系统实时性的要求, 且定位参数的求解也完全正确.     

基于Hausdorff距离的手势识别

随着先进人机交互技术的提出及发展，手势识别正成为其中一项关键技术，基于视觉的手势识别是当前涉及图象处理，模式识别，计算机视觉等领域的一个比较活跃的课题，由于Hausdorff距离模板匹配的方法具有计算量小，适应性强的特点，因此基于Hausdorff距离，建立了一个手势识别系统，该系统采用边缘特征像素点作为识别特征，并首次利用Hausdorff距离模板匹配的思想，在距离变换空间内，实现了中国手指字母集上的基于单目视觉的30个手指字母的手势识别，为提高系统的鲁棒性，还提出了修正的Hausdorff距离形式，测试集上的平均识别率为96．7％，实验结果表明，基于Hausdorff距离的模板匹配方法用于基于听觉的静态手势识别是可行的。     

Spatially eigen-weighted Hausdorff distances for human face recognition

Hausdorff distance is an efficient measure of the similarity of two point sets. In this paper, we propose a new spatially weighted Hausdorff distance measure for human face recognition. The weighting function used in the Hausdorff distance measure is based on an eigenface, which has a large value at locations of importance facial features and can reflect the face structure more effectively. Two modified Hausdorff distances, namely, “spatially eigen-weighted Hausdorff distance” (SEWHD) and “spatially eigen-weighted ‘doubly’ Hausdorff distance” (SEW2HD) are proposed, which incorporate the information about the location of important facial features such as eyes, mouth, and face contour so that distances at those regions will be emphasized. Experimental results based on a combination of the ORL, MIT, and Yale face databases show that SEW2HD can achieve recognition rates of 83%, 90% and 92% for the first one, the first three and the first five likely matched faces, respectively, while the corresponding recognition rates of SEWHD are 80%, 83% and 88%, respectively.     

Hybrid image matching combining Hausdorff distance with normalized gradient matching

Image matching has been a central problem in computer vision and image processing for decades. Most of the previous approaches to image matching can be categorized into the intensity-based and edge-based comparison. Hausdorff distance has been widely used for comparing point sets or edge maps since it does not require point correspondences. In this paper, we propose a new image similarity measure combining the Hausdorff distance with a normalized gradient consistency score for image matching. The normalized gradient consistency score is designed to compare the normalized image gradient fields between two images to alleviate the illumination variation problem in image matching. By combining the edge-based and intensity-based information for image matching, we are able to achieve robust image matching under different lighting conditions. We show the superior robustness property of the proposed image matching technique through experiments on face recognition under different lighting conditions.     

一种基于Hausdorff 度量的多传感器图像配准方法

描述了一种基于Hausdorff 度量的合成孔径雷达和光学图像配准方法。首先用基于低帽滤波的方法提取待配准图像的闭合轮廓。然后对较长的轮廓进行Hausdorff 度量初匹配, 并对初匹配的结果使用轮廓中心的相对距离比直方图聚束检测法进行一致性检测。最后, 在得到正确的闭合轮廓对后, 使用最小二乘法计算图像的变换参数。考虑到雷达图像的相干斑噪声以及多传感器图像成像时间造成的变形, 多传感器图像提取的轮廓会有一定的差别。而Hausdorff 度量对误差有很好的容忍性, 因此本方法可以对多传感器图像进行配准。     

Face recognition based on 3D ridge images obtained from range data

In this paper, we present an approach for 3D face recognition from frontal range data based on the ridge lines on the surface of the face. We use the principal curvature, k_max, to represent the face image as a 3D binary image called ridge image. The ridge image shows the locations of the ridge points around the important facial regions on the face (i.e., the eyes, the nose, and the mouth). We utilized the robust Hausdorff distance and the iterative closest points (ICP) for matching the ridge image of a given probe image to the ridge images of the facial images in the gallery. To evaluate the performance of our approach for 3D face recognition, we performed experiments on GavabDB face database (a small size database) and Face Recognition Grand Challenge V2.0 (a large size database). The results of the experiments show that the ridge lines have great capability for 3D face recognition. In addition, we found that as long as the size of the database is small, the performance of the ICP-based matching and the robust Hausdorff matching are comparable. But, when the size of the database increases, ICP-based matching outperforms the robust Hausdorff matching technique.