Study on an improved Hausdorff distance for multi-sensor image matching

A new modifying Hausdorff distance image matching algorithm was proposed in this paper. After the corners of two images was extracted using Harris corner detector, a kind of Hausdorff distance integrating points set coincidence numbers was presented to aim at the traditional Hausdorff distance. The accuracy of matching was improved by this modifying. Hausdorff distance coefficient matrix is calculating by corners neighborhood’s related matching. The initial matching point-pairs are obtained by the rule that the small coefficient is good matching. Finally the wrong matching point-pairs are deleted by the distance-ration invariant, the right matching point-pairs are acquired. Experimental results show that the proposed method can be easily and quickly to process the multiple sensor images.     

图像特征点提取角点量阈值自适应选取方法

针对图像特征点提取中在固定的角点量阂值时,由于拍摄物体自身纹理受光照的不均匀,可能会引起角点的提取效果不佳的现状,提出一种角点量自适应选取方法。阐述了角点量自适应选取方法的增点法和删点法两种实现形式,并分别通过对模拟和实拍图像特征点的提取,定量和定性验证了自适应角点量阈值方法相对于固定角点量阈值方法的优势。     

基于Harris角点检测器的指纹细节点提取算法

提出了一种基于Harris角点检测器的指纹细节点提取算法。先将Harris角点检测器应用于增强后的指纹图像,检测出指纹的细节点和曲率变化大的点,随后进行后处理操作。在后处理操作中,根据细节点的空间分布特征,删除虚假点。使用细节点的邻域灰度信息,判定细节点的类型。利用细节点的原始方向以及得到的类型,确定细节点的精确方向。与经典的细节点提取算法相比,不需要对指纹图像进行二值化、细化,直接在灰度指纹图像当中提取细节点,大大减少了计算时间,有效地提高了效率。使用FVC2002指纹数据库测试,结果表明,该算法可靠、快速,适合实际应用。     

Magnetic Second-Order Topological Insulator: An Experimentally Feasible 2D CrSiTe3

2D second-order topological insulators (SOTIs) have sparked significant interest, but currently, the proposed realistic 2D materials for SOTIs are limited to nonmagnetic systems. In this study, for the first time, a single layer of chalcogenide CrSiTe₃—an experimentally realized transition metal trichalcogenide is proposed with a layer structure—as a 2D ferromagnetic (FM) SOTI. Based on first-principles calculations, this study confirms that the CrSiTe₃ monolayer exhibits a nontrivial gapped bulk state in the spin-up channel and a trivial gapped bulk state in the spin-down channel. Based on the higher-order bulk–boundary correspondence, it demonstrates that the CrSiTe₃ monolayer exhibits topologically protected corner states with a quantized fractional charge ($\frac{e}{3}$) in the spin-up channel. Notably, unlike previous nonmagnetic examples, the topological corner states of the CrSiTe₃ monolayer are spin-polarized and pinned at the corners of the sample in real space. Furthermore, the CrSiTe₃ monolayer retains SOTI features when the spin–orbit coupling (SOC) is considered, as evidenced by the corner charge and corner states distribution. Finally, by applying biaxial strain and hole doping, this study transforms the magnetic insulating bulk states into spin-gapless semiconducting and half-metallic bulk states, respectively. Importantly, the topological corner states persist in the spin-up channel under these conditions.