Point cloud compression is critical to deploy 3D representation of the physical world such as 3D immersive telepresence,autonomous driving,and cultural heritage preservation.However,point cloud data are distributed ir...Point cloud compression is critical to deploy 3D representation of the physical world such as 3D immersive telepresence,autonomous driving,and cultural heritage preservation.However,point cloud data are distributed irregularly and discontinuously in spatial and temporal domains,where redundant unoccupied voxels and weak correlations in 3D space make achieving efficient compression a challenging problem.In this paper,we propose a spatio-temporal context-guided algorithm for lossless point cloud geometry compression.The proposed scheme starts with dividing the point cloud into sliced layers of unit thickness along the longest axis.Then,it introduces a prediction method where both intraframe and inter-frame point clouds are available,by determining correspondences between adjacent layers and estimating the shortest path using the travelling salesman algorithm.Finally,the few prediction residual is efficiently compressed with optimal context-guided and adaptive fastmode arithmetic coding techniques.Experiments prove that the proposed method can effectively achieve low bit rate lossless compression of point cloud geometric information,and is suitable for 3D point cloud compression applicable to various types of scenes.展开更多
The compressive behaviour of paper honeycombs is studied by means of an experimental analysis. Experiment results show how geometry aspects of hexagonal paper honeycombs, e.g. the height of paper honeycomb, the thickn...The compressive behaviour of paper honeycombs is studied by means of an experimental analysis. Experiment results show how geometry aspects of hexagonal paper honeycombs, e.g. the height of paper honeycomb, the thickness and length of honeycomb cell-wall, the drawing ratio of hexagonal honeycomb, affect the compressive properties of the paper honeycombs. It is in good agreement with the theory model. The constraint factor K of the critical buckling stress is mainly determined by the length of honeycomb cell-wail. It can be described as K=1.54 for B type paper honeycombs and K=3.32 for D type paper honeycombs. The plateau stress is the power exponent function of the thickness to length ratio of honeycomb cell-wall, and the experiment results show that the constant is 13.2 and the power exponent is 1.77. The research results can be used to characterize and improve efficiently the compressive properties of paper honeycombs.展开更多
Two salicylate containing mononuclear manganese complexes formulated as [Mnand characterized by elemental analysis, IR and single-crystal X-ray diffraction analyses. Crystal data for compound 1： monoclinic, space gro...Two salicylate containing mononuclear manganese complexes formulated as [Mnand characterized by elemental analysis, IR and single-crystal X-ray diffraction analyses. Crystal data for compound 1： monoclinic, space group C2/c, a=30.748（6）, b=8.1933（13）, c=21.137（4） A, β=126.772（4）°, V=4265.5（13）A^3, Z=8, Mr=471.34, Dc=1.468 g/cm^3, μ=0.667 mm^-1, F（000）=1952,the final R=0.0637, wR=0.1783 （I 〉 2σ（I）） and GOOF=1.073; and those for compound 2： monoclinic,space group C2/c, a=14.505（5）, b=11.048（4）, c=20.711 （7）（A）, β=103.603（6）°, V=3225.6 （18）A^3, Z=4, Mr=668.65, Dc=1.377 g/cm^3, μ=0.466 mm^-1, F（000）=1416, the final R=0.0373, wR=0.1125 （I 〉2σ（I））, and GOOF=1.000. The Mn atoms of both complexes are six-coordinated in an axially elongated octahedral geometry for 1 and an axially compressed octahedral geometry for 2, and their oxidation states have been determined to be trivalent by bond valence sum calculation.展开更多
Compression of mesh attributes becomes a challenging problem due to the greatneed for efficient storage and fast transmission. This paper presents a novel geometric signalcompression framework for all mesh attributes,...Compression of mesh attributes becomes a challenging problem due to the greatneed for efficient storage and fast transmission. This paper presents a novel geometric signalcompression framework for all mesh attributes, including position coordinates, normal, color,texture, etc. Within this framework, mesh attributes are regarded as geometric signals defined onmesh surfaces. A planar parameterization algorithm is first proposed to map 3D meshes to 2Dparametric meshes. Geometric signals are then transformed into 2D signals, which are sampled into 2Dregular signals using an adaptive sampling method. The JPEG2000 standard for still imagecompression is employed to effectively encode these regular signals into compact bit-streams withhigh rate/distortion ratios. Experimental results demonstrate the great application potentials ofthis framework.展开更多
文摘Point cloud compression is critical to deploy 3D representation of the physical world such as 3D immersive telepresence,autonomous driving,and cultural heritage preservation.However,point cloud data are distributed irregularly and discontinuously in spatial and temporal domains,where redundant unoccupied voxels and weak correlations in 3D space make achieving efficient compression a challenging problem.In this paper,we propose a spatio-temporal context-guided algorithm for lossless point cloud geometry compression.The proposed scheme starts with dividing the point cloud into sliced layers of unit thickness along the longest axis.Then,it introduces a prediction method where both intraframe and inter-frame point clouds are available,by determining correspondences between adjacent layers and estimating the shortest path using the travelling salesman algorithm.Finally,the few prediction residual is efficiently compressed with optimal context-guided and adaptive fastmode arithmetic coding techniques.Experiments prove that the proposed method can effectively achieve low bit rate lossless compression of point cloud geometric information,and is suitable for 3D point cloud compression applicable to various types of scenes.
基金This project is supported by Guangdong Provincial Key Laboratory Foundation of Higher Education Institutions, China.
文摘The compressive behaviour of paper honeycombs is studied by means of an experimental analysis. Experiment results show how geometry aspects of hexagonal paper honeycombs, e.g. the height of paper honeycomb, the thickness and length of honeycomb cell-wall, the drawing ratio of hexagonal honeycomb, affect the compressive properties of the paper honeycombs. It is in good agreement with the theory model. The constraint factor K of the critical buckling stress is mainly determined by the length of honeycomb cell-wail. It can be described as K=1.54 for B type paper honeycombs and K=3.32 for D type paper honeycombs. The plateau stress is the power exponent function of the thickness to length ratio of honeycomb cell-wall, and the experiment results show that the constant is 13.2 and the power exponent is 1.77. The research results can be used to characterize and improve efficiently the compressive properties of paper honeycombs.
基金This work was supported by the NNSFC (No. 20471061)the Science & Technology Innovation Foundation for the Young Scholar of Fujian Province (No. 2005J059)
文摘Two salicylate containing mononuclear manganese complexes formulated as [Mnand characterized by elemental analysis, IR and single-crystal X-ray diffraction analyses. Crystal data for compound 1： monoclinic, space group C2/c, a=30.748（6）, b=8.1933（13）, c=21.137（4） A, β=126.772（4）°, V=4265.5（13）A^3, Z=8, Mr=471.34, Dc=1.468 g/cm^3, μ=0.667 mm^-1, F（000）=1952,the final R=0.0637, wR=0.1783 （I 〉 2σ（I）） and GOOF=1.073; and those for compound 2： monoclinic,space group C2/c, a=14.505（5）, b=11.048（4）, c=20.711 （7）（A）, β=103.603（6）°, V=3225.6 （18）A^3, Z=4, Mr=668.65, Dc=1.377 g/cm^3, μ=0.466 mm^-1, F（000）=1416, the final R=0.0373, wR=0.1125 （I 〉2σ（I））, and GOOF=1.000. The Mn atoms of both complexes are six-coordinated in an axially elongated octahedral geometry for 1 and an axially compressed octahedral geometry for 2, and their oxidation states have been determined to be trivalent by bond valence sum calculation.
文摘Compression of mesh attributes becomes a challenging problem due to the greatneed for efficient storage and fast transmission. This paper presents a novel geometric signalcompression framework for all mesh attributes, including position coordinates, normal, color,texture, etc. Within this framework, mesh attributes are regarded as geometric signals defined onmesh surfaces. A planar parameterization algorithm is first proposed to map 3D meshes to 2Dparametric meshes. Geometric signals are then transformed into 2D signals, which are sampled into 2Dregular signals using an adaptive sampling method. The JPEG2000 standard for still imagecompression is employed to effectively encode these regular signals into compact bit-streams withhigh rate/distortion ratios. Experimental results demonstrate the great application potentials ofthis framework.
