A modified Fourier descriptor was presented. Information from a local space can be used more efficiently. After the boundary pixel set of an object was computed, centroid distance approach was used to compute shape si...A modified Fourier descriptor was presented. Information from a local space can be used more efficiently. After the boundary pixel set of an object was computed, centroid distance approach was used to compute shape signature in the local space. A pair of shape signature and boundary pixel gray was used as a point in a feature space. Then, Fourier transform was used for composition of point information in the feature space so that the shape features could be computed. It is proved theoretically that the shape features from modified Fourier descriptors are invariant to translation, rotation, scaling, and change of start point. It is also testified by measuring the retrieval performance of the systems that the shape features from modified Fourier descriptors are more discriminative than those from other Fourier descriptors.展开更多
基金Project(60873010)supported by the National Natural Science Foundation of ChinaProject supported by the Doctor Startup Foundation of Shenyang University of Technology,China
文摘A modified Fourier descriptor was presented. Information from a local space can be used more efficiently. After the boundary pixel set of an object was computed, centroid distance approach was used to compute shape signature in the local space. A pair of shape signature and boundary pixel gray was used as a point in a feature space. Then, Fourier transform was used for composition of point information in the feature space so that the shape features could be computed. It is proved theoretically that the shape features from modified Fourier descriptors are invariant to translation, rotation, scaling, and change of start point. It is also testified by measuring the retrieval performance of the systems that the shape features from modified Fourier descriptors are more discriminative than those from other Fourier descriptors.
文摘为了提高潜孔钻机定位的精度,提出采用双目立体视觉技术获得潜孔钻机定位过程中孔位标识的三维位置信息,用于指导潜孔钻机进行自动钻孔定位.首先利用双目摄像机获取含有孔位标识的图像对,然后采用隶属度函数为梯形函数的模糊阈值分割方法对孔位标识进行识别分割,利用图像的不变矩原理求取孔位标识的质心,并通过三角测量原理求取孔位的空间位置信息.最后,在潜孔钻机试验台上进行了基于双目立体视觉系统的自动定位试验.结果表明,所采用以灰度直方图为基础的模糊阈值分割能够实现对孔位标识有效信息的提取,且定位误差小于25 mm.