In this paper, Fourier and Wavelet transformation were adopted to analyze shape char- acteristics, with twelve simple shapes and two types of second phases from real microstructure mor- phology. According to the resul...In this paper, Fourier and Wavelet transformation were adopted to analyze shape char- acteristics, with twelve simple shapes and two types of second phases from real microstructure mor- phology. According to the results of Fast Fourier transformation （FFT）, the Fourier descriptors can be used to characterize the shape from the aspects of the first eight Normalization amplitudes, the number of the largest amplitudes to inverse reconstruction, similarity of shapes and profile roughness. And the Diepenbroek Roughness was rewritten by Normalization amplitudes of FFT results. Moreover, Sum Square of Relative Errors （SSRE） of Wavelet transformation （WT） signal sequence, including approximation signals and detail signals, was introduced to evaluate the simi- larity and relative orientation among shapes. As a complement to FFT results, the WT results can retain more detailed information of shapes including their orientations. Besides, the geometric sig- natures of the second phases were extracted by image processing and then were analyzed by means of FFT and WT.展开更多
In this paper, we propose a new shape-coding algorithm called wavelet-based shape coding (WBSC). Performing wavelet transform on the orientation of original planar curve gives the corners called corner-1 points and en...In this paper, we propose a new shape-coding algorithm called wavelet-based shape coding (WBSC). Performing wavelet transform on the orientation of original planar curve gives the corners called corner-1 points and end of arcs that belong to the original curve. Each arc is represented by a broken line and the corners called corner-2 points of the broken line are extracted. A polygonal approximation of a contour is an ordered list of corner-1 points, ends of arcs and corner-2 points which are extracted by using the above algorithm. All of the points are called polygonal vertices which will be compressed by our adaptive arithmetic encoding. Experimental results show that our method reduces code bits by about 26% compared with the context-based arithmetic encoding (CAE) of MPEG-4, and the subjective quality of the reconstructed shape is better than that of CAE at the same Dn.展开更多
基于高斯差分小波(Difference of Gaussians,DOG)向球面上拓展产生的球面DOG小波函数,提出了基于球面DOG小波框架重构骨料形状的新方法。为探讨该方法的优势,采用该方法和传统球谐重构法,对采用三维扫描仪获取机制砂的表面点云数据进行...基于高斯差分小波(Difference of Gaussians,DOG)向球面上拓展产生的球面DOG小波函数,提出了基于球面DOG小波框架重构骨料形状的新方法。为探讨该方法的优势,采用该方法和传统球谐重构法,对采用三维扫描仪获取机制砂的表面点云数据进行重构,分析了球面DOG小波框架方法的参数设置,以及准确性。结果显示,随着球面DOG小波框架qmax的增大,重构骨料的形貌逐渐接近真实形态。且当qmax达到4时,支撑集足够小的球面DOG小波可有效避免高阶次球谐级数重构多棱角骨料时由于振铃效应导致的重构精度下降问题。展开更多
基金the support received from the National Natural Science Foundation of China (No.51275414)the Aeronautical Science Foundation of China (No.2011ZE53059)
文摘In this paper, Fourier and Wavelet transformation were adopted to analyze shape char- acteristics, with twelve simple shapes and two types of second phases from real microstructure mor- phology. According to the results of Fast Fourier transformation （FFT）, the Fourier descriptors can be used to characterize the shape from the aspects of the first eight Normalization amplitudes, the number of the largest amplitudes to inverse reconstruction, similarity of shapes and profile roughness. And the Diepenbroek Roughness was rewritten by Normalization amplitudes of FFT results. Moreover, Sum Square of Relative Errors （SSRE） of Wavelet transformation （WT） signal sequence, including approximation signals and detail signals, was introduced to evaluate the simi- larity and relative orientation among shapes. As a complement to FFT results, the WT results can retain more detailed information of shapes including their orientations. Besides, the geometric sig- natures of the second phases were extracted by image processing and then were analyzed by means of FFT and WT.
文摘In this paper, we propose a new shape-coding algorithm called wavelet-based shape coding (WBSC). Performing wavelet transform on the orientation of original planar curve gives the corners called corner-1 points and end of arcs that belong to the original curve. Each arc is represented by a broken line and the corners called corner-2 points of the broken line are extracted. A polygonal approximation of a contour is an ordered list of corner-1 points, ends of arcs and corner-2 points which are extracted by using the above algorithm. All of the points are called polygonal vertices which will be compressed by our adaptive arithmetic encoding. Experimental results show that our method reduces code bits by about 26% compared with the context-based arithmetic encoding (CAE) of MPEG-4, and the subjective quality of the reconstructed shape is better than that of CAE at the same Dn.
文摘基于高斯差分小波(Difference of Gaussians,DOG)向球面上拓展产生的球面DOG小波函数,提出了基于球面DOG小波框架重构骨料形状的新方法。为探讨该方法的优势,采用该方法和传统球谐重构法,对采用三维扫描仪获取机制砂的表面点云数据进行重构,分析了球面DOG小波框架方法的参数设置,以及准确性。结果显示,随着球面DOG小波框架qmax的增大,重构骨料的形貌逐渐接近真实形态。且当qmax达到4时,支撑集足够小的球面DOG小波可有效避免高阶次球谐级数重构多棱角骨料时由于振铃效应导致的重构精度下降问题。
