Statistical shape models(SSMs)are effective for image processing and analysis and have been used in various medical fields,including face recognition and cranial bone recognition.In orthopedics,SSMs are being used in ...Statistical shape models(SSMs)are effective for image processing and analysis and have been used in various medical fields,including face recognition and cranial bone recognition.In orthopedics,SSMs are being used in numerous applications,such as automated segmentation of medical images,preoperative planning,intraoper-ative navigation combined with robotics,simulation reconstruction of defects,human biomechanics research,description of anatomical shape changes,and prosthesis design.This review highlighted the wide range of ap-plications while acknowledging the diversity of methodologies and techniques encompassed by SSMs,including Gaussian process models and nonlinear solutions.In addition,the available software packages for constructing shape models,such as Scalismo,ShapeWorks,and Deformetrica,were discussed.展开更多
Particle shape plays an important role in both the micro and macro scales responses of a granular assem- bly. This paper presents a systematic way to interpret the shape effects of granular material during quasi-stati...Particle shape plays an important role in both the micro and macro scales responses of a granular assem- bly. This paper presents a systematic way to interpret the shape effects of granular material during quasi-static shearing. A more suitable shape descriptor is suggested for the quantitative analysis of the macroscale strength indexes and contact parameters for non-convex grains, with special consid- eration given to the peak state and critical state. Through a series of numerical simulations and related post-processing analysis, particle shape is found to directly influence the strain localisation patterns, microscale fabric distributions, microscale mobilisation indexes, and probability distribution of the nor- malised contact normal force. Additionally, the accuracy of the stress-force-fabric relationship can be influenced by the average normal force and the distribution of contact vectors. Moreover, particle shape plays a more important role than do the confining pressures in determining the friction angle. Strong force chains and the dilation effect are also found to be strongly influenced by the high confinin~ oressure.展开更多
Precise facial feature extraction is essential to the high-level face recognition and expression analysis. This paper presents a novel method for the real-time geometric facial feature extraction from live video. In t...Precise facial feature extraction is essential to the high-level face recognition and expression analysis. This paper presents a novel method for the real-time geometric facial feature extraction from live video. In this paper, the input image is viewed as a weighted graph. The segmentation of the pixels corresponding to the edges of facial components of the mouth, eyes, brows, and nose is implemented by means of random walks on the weighted graph. The graph has an 8-connected lattice structure and the weight value associated with each edge reflects the likelihood that a random walker will cross that edge. The random walks simulate an anisot- ropic diffusion process that filters out the noise while preserving the facial expression pixels. The seeds for the segmentation are obtained from a color and motion detector. The segmented facial pixels are represented with linked lists in the origi- nal geometric form and grouped into different parts corresponding to facial components. For the convenience of implementing high-level vision, the geometric description of facial component pixels is further decomposed into shape and reg- istration information. Shape is defined as the geometric information that is invariant under the registration transformation, such as translation, rotation, and isotropic scale. Statistical shape analysis is carried out to capture global facial fea- tures where the Procrustes shape distance measure is adopted. A Bayesian ap- proach is used to incorporate high-level prior knowledge of face structure. Experimental results show that the proposed method is capable of real-time extraction of precise geometric facial features from live video. The feature extraction is robust against the illumination changes, scale variation, head rotations, and hand interference.展开更多
基金supported by the Yunnan Provincial Department of Science and Technology(Grant No.202401AU070121)Yunnan Orthopedics and Sports Rehabilitation Clinical Medicine Research Center(Grant No.202102AA310068)+3 种基金Yunnan Provincial Clinical Orthopaedic Trauma Medical Center(Second Cycle)Clinical Key Subject Construction Project of PLAMedical Key Subject of Joint Logistic Support Force of PLA(Grant No.145AHQ146009000X)Yunnan Key Laboratory of Digital Orthopaedics.
文摘Statistical shape models(SSMs)are effective for image processing and analysis and have been used in various medical fields,including face recognition and cranial bone recognition.In orthopedics,SSMs are being used in numerous applications,such as automated segmentation of medical images,preoperative planning,intraoper-ative navigation combined with robotics,simulation reconstruction of defects,human biomechanics research,description of anatomical shape changes,and prosthesis design.This review highlighted the wide range of ap-plications while acknowledging the diversity of methodologies and techniques encompassed by SSMs,including Gaussian process models and nonlinear solutions.In addition,the available software packages for constructing shape models,such as Scalismo,ShapeWorks,and Deformetrica,were discussed.
文摘Particle shape plays an important role in both the micro and macro scales responses of a granular assem- bly. This paper presents a systematic way to interpret the shape effects of granular material during quasi-static shearing. A more suitable shape descriptor is suggested for the quantitative analysis of the macroscale strength indexes and contact parameters for non-convex grains, with special consid- eration given to the peak state and critical state. Through a series of numerical simulations and related post-processing analysis, particle shape is found to directly influence the strain localisation patterns, microscale fabric distributions, microscale mobilisation indexes, and probability distribution of the nor- malised contact normal force. Additionally, the accuracy of the stress-force-fabric relationship can be influenced by the average normal force and the distribution of contact vectors. Moreover, particle shape plays a more important role than do the confining pressures in determining the friction angle. Strong force chains and the dilation effect are also found to be strongly influenced by the high confinin~ oressure.
基金the National Natural Science Foundation of China (Grant No. 60672071)the Ministry of Science and Technology (Grant No. 2005CCA04400)the Ministry of Education (Grant No. NCET-05-0534)
文摘Precise facial feature extraction is essential to the high-level face recognition and expression analysis. This paper presents a novel method for the real-time geometric facial feature extraction from live video. In this paper, the input image is viewed as a weighted graph. The segmentation of the pixels corresponding to the edges of facial components of the mouth, eyes, brows, and nose is implemented by means of random walks on the weighted graph. The graph has an 8-connected lattice structure and the weight value associated with each edge reflects the likelihood that a random walker will cross that edge. The random walks simulate an anisot- ropic diffusion process that filters out the noise while preserving the facial expression pixels. The seeds for the segmentation are obtained from a color and motion detector. The segmented facial pixels are represented with linked lists in the origi- nal geometric form and grouped into different parts corresponding to facial components. For the convenience of implementing high-level vision, the geometric description of facial component pixels is further decomposed into shape and reg- istration information. Shape is defined as the geometric information that is invariant under the registration transformation, such as translation, rotation, and isotropic scale. Statistical shape analysis is carried out to capture global facial fea- tures where the Procrustes shape distance measure is adopted. A Bayesian ap- proach is used to incorporate high-level prior knowledge of face structure. Experimental results show that the proposed method is capable of real-time extraction of precise geometric facial features from live video. The feature extraction is robust against the illumination changes, scale variation, head rotations, and hand interference.
