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Corner detection by local histograms of contour chain code 总被引:4,自引:0,他引:4
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Fast and accurate snake model for object contour detection 总被引:2,自引:0,他引:2
Wen-Nung Lie Cheng-Hung Chuang 《Electronics letters》2001,37(10):624-626
A new scheme in which a snake model is used for object contour detection is proposed. By developing a no-search movement scheme, accepting the effective gradient vector flow field as the contracting force, and adjusting the weighting parameters automatically, an algorithm that is fast, less sensitive to initial contour conditions and accurate in approaching concave parts of an object boundary is obtained 相似文献
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This paper proposes a global mapping algorithm for multiple robots from an omnidirectional‐vision simultaneous localization and mapping (SLAM) approach based on an object extraction method using Lucas–Kanade optical flow motion detection and images obtained through fisheye lenses mounted on robots. The multi‐robot mapping algorithm draws a global map by using map data obtained from all of the individual robots. Global mapping takes a long time to process because it exchanges map data from individual robots while searching all areas. An omnidirectional image sensor has many advantages for object detection and mapping because it can measure all information around a robot simultaneously. The process calculations of the correction algorithm are improved over existing methods by correcting only the object's feature points. The proposed algorithm has two steps: first, a local map is created based on an omnidirectional‐vision SLAM approach for individual robots. Second, a global map is generated by merging individual maps from multiple robots. The reliability of the proposed mapping algorithm is verified through a comparison of maps based on the proposed algorithm and real maps. 相似文献
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A novel dominant point matching algorithm is designed and developed for occluded object recognition. The developed algorithm is capable of grouping all scattered dominant points on an object boundary, due to occlusion, into a single representation for recognition. A set of handtools is selected to evaluate the performance of the algorithm and the results are encouraging.<> 相似文献
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Conformal Snake algorithm for contour detection 总被引:1,自引:0,他引:1
A novel and effective modification of the original Snake algorithm is proposed. The modification can improve the capability of the algorithm to detect boundaries with sharp comers or concave parts without the need to introduce external forces. The essential idea is to apply conformal mapping to transform the image so that the object boundary in the new domain can be captured by the Snake algorithm 相似文献
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以DWG数字地图为例,研究如何快速准确获取数字地图中的居民地(房屋)注记.居民地注记属于点状要素,且一般位于居民地内部.根据这一特点,自动获取居民地注记的关键就是判断注记属于哪个多边形.对传统射线法进行改进,提出了去除顶点交点法判断点在多边形内外算法,并在某市数字地图数据入库中得到了应用,结果表明,该算法可行有效. 相似文献
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为了解决当前目标跟踪中目标轮廓提取不精确的问 题,在对传统GVF (gradient vector flow)snake活动轮廓模型改进的基础上,提 出一种基于变化检测和改进的GVF snake活动轮廓模型的视频目标轮廓提取算法。首先,通 过 基于t显著性检验的变化检测方 法消除背景边界的影响,并获取初始运动变化区域的临界四边形作为GVF snake的初始轮廓 。然后,对初始轮廓应用改进 的GVF snake模型以获得精确的轮廓边界。改进模型采用4方向各项异性扩散,并采用下降速 度较快的保真项系数以增强 GVF snake进入凹陷的能力,且保持对弱边界的收敛。本文方法克服了手动绘制初始轮廓的 缺点,对传统GVF snake方法进 行了改进,且空间准确度(SA)有很大提高。实验表明 ,本文方法成功分割出目标凹陷部分并对弱边界有较好的收敛效果,提高了轮廓提取的精确 度。 相似文献
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A new method for reconstructing a 3-dimensional object from serial cross-sectionsis presented in this paper.The method is based on the principle of sampling and considersevery point in cross-sections as a sampling point and performs the interpolating of nonlinearfunction with these sampling points.Compared with other methods,this method has manyadvantages such as higher precision and fewer requested known sampling points.The result ofreconstruction with this method is an“entity”which involves the exterior shape and interiorconstruction information of the object simultaneously. 相似文献
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为了提高激光雷达点云滤波算法的精度和自适应性,对移动曲面滤波算法进行改进。采用格网边界点构建曲面约束条件,检验格网内是否全部为建筑物点。利用区域拟合求解地形的起伏,引入机器学习中高斯混合模型(GMM)对地形起伏进行滤波分类,将移动曲面中的种子点作为聚类算法中的靶向点参与分类学习。实验数据为雷达飞行的自测区,对于自测区采用随机抽样的方式,检验判断滤波效果。同时为检验GMM算法的准确性,在三类误差检验方式的基础上,增加了Kappa系数作为检验方式。通过与谱系聚类分类算法对比,证明所提算法能取得较好的滤波效果。 相似文献
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Propagation of radiowaves over irregular terrain and in an inhomogeneous atmosphere is solved by the parabolic equation method using the split-step Fourier algorithm on a terrain-conformal mesh. A piecewise continuous coordinate system is generated by the specification of: (1) the terrain profile shape at discrete points and (2) an upper height. The resulting mesh is conformal to the terrain at the lower boundary and gradually flattens off at the maximum height. In addition to preserving the number of points on any vertical line between the terrain and the maximum height from one range step to another, the coordinate transformation used in the paper produces a correction term in the refractive index whose gradient diminishes with height. As a result, the sampling requirements over steep terrain are relaxed when compared to the Beilis-Tappert transformation. Formulation and results are given both for the horizontal and vertical polarizations 相似文献
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针对机载LiDAR建筑物点云提取过程中与树木紧邻的建筑物难以提取,已有先滤波后提取算法效率低等问题,提出一种结合区域生长与主成分分析的机载LiDAR建筑物点云提取算法。该算法首先对粗差剔除后的机载LiDAR离散点云构建TIN三角网,依据建筑物边缘点所在三角形的特征提取建筑物边缘点;然后将邻域特征优化后的建筑物边缘点作为种子点进行区域生长得到建筑物点云;最后采用主成分分析对提取结果进行检核,剔除非建筑物点云,在此基础上基于连通性对建筑物点云进行单体化分割,剔除小面积区域,得到最终的建筑物激光脚点数据。实验选取国际摄影测量与遥感协会提供的三组典型区域的LiDAR点云数据进行建筑物提取,并与传统形态学和区域生长两种建筑物点云提取算法进行比较,结果表明本文算法可以实现建筑物点云的高精度提取,且对地形及不同类型屋顶的建筑物具有良好的自适应性,验证了算法的可靠性。 相似文献
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设计并优化了线段与圆关于任意多边形边界(包括凸多边形及凹多边形边界)的裁剪算法。求出每一条边界与所要裁剪的线段和圆的交点并排序,利用交点将裁剪对象分割成线段、圆弧,通过计算线段和圆弧的中点并判断其与边界的位置关系来完成对图形的裁剪。文中给出了算法具体描述,通过对算法复杂度的分析,该算法的效率与以往的一些经典算法相比有了较大提高。 相似文献
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图的顶点着色问题是指无向图中任意两个相邻顶点都分配到不同的颜色,这个问题是著名的NP-完全问题,没有非常有效的算法.但在1994年Adleman[1]首次提出用DNA计算解决NP-完全问题,设计出一种全新的计算模式—模拟生物分子DNA的结构并借助于分子生物技术进行计算,使得NP-完全问题的求解可能得到解决.本文首先提出了基于分子生物技术的图的顶点着色问题的DNA算法,算法的关键是对图中的顶点和顶点的颜色进行恰当的编码,以便于使用常规的生物操作及生物酶完成解的产生及最终解的分离,依据分子生物学的实验方法,本文提出的算法是有效和可行的;其次指出了该算法的优点、存在的问题及将来进一步的研究方向. 相似文献
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一种基于距离调节的聚类算法 总被引:2,自引:1,他引:1
针对k-means算法不适合凹形样本空间的问题,提出了一种基于距离调节的聚类算法.算法中引入了一种调节最短路径距离作为算法的相似度函数,该函数可以使经过高密度数据区域的两点距离缩短,而经过低密度数据区域的两点距离加长,由此来缩小类间样本的相似度,同时加大类间的相似度,以及更好的聚类.实验结果证明,该算法对凹状的聚类样本空间具有很好的聚类效果. 相似文献
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针对封闭式STL三角网格模型中的孔洞提出了一种修补算法。首先根据网格中边与三角形之间的邻接关系提取孔洞边界,然后计算孔洞边界点的平滑度,根据其不同的平滑度和不同大小的夹角在孔洞中依次填补新的三角形,并验证添加顶点的进行合法性。这样逐渐收缩,直至修补完毕。实验结果证明,该算法简单、有效,孔洞修补效果好。 相似文献