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LOCALIZATION OF OBJECT (SPINE) IN MEDICAL IMAGE USING ACTIVE SHAPE MODELS 被引量:2
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作者 徐涛 蔡宇新 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2003年第2期211-217,共7页
Active shape models (ASM), consisting of a shape model and a local gray-level appearance model, can be used to locate the objects in images. In original ASM scheme, the model of object′s gray-level variations is base... Active shape models (ASM), consisting of a shape model and a local gray-level appearance model, can be used to locate the objects in images. In original ASM scheme, the model of object′s gray-level variations is based on the assumption of one-dimensional sampling and searching method. In this work a new way to model the gray-level appearance of the objects is explored, using a two-dimensional sampling and searching technique in a rectangular area around each landmark of object shape. The ASM based on this improvement is compared with the original ASM on an identical medical image set for task of spine localization. Experiments demonstrate that the method produces significantly fast, effective, accurate results for spine localization in medical images. 展开更多
关键词 object localization active shape models (ASM) gray-level appearance model principal component analysis SPINE
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Optimal shape space and searching in the active shape model
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作者 何良华 邹采荣 +1 位作者 赵力 胡蝶 《Journal of Southeast University(English Edition)》 EI CAS 2005年第3期263-267,共5页
A novel idea,called the optimal shape subspace (OSS) is first proposed for optimizing active shape model (ASM) search.It is constructed from the principal shape subspace and the principal shape variance subspace.I... A novel idea,called the optimal shape subspace (OSS) is first proposed for optimizing active shape model (ASM) search.It is constructed from the principal shape subspace and the principal shape variance subspace.It allows the reconstructed shape to vary more than that reconstructed in the standard ASM shape space,hence it is more expressive in representing shapes in real life.Then a cost function is developed,based on a study on the search process.An optimal searching method using the feedback information provided by the evaluation cost is proposed to improve the performance of ASM alignment.Experimental results show that the proposed OSS can offer the maximum shape variation with reserving the principal information and a unique local optimal shape is acquired after optimal searching.The combination of OSS and optimal searching can improve the ASM performance greatly. 展开更多
关键词 active shape model shape subspace search subspace principal component analysis
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基于MDL Shape Model及EFD的行人轮廓2D+time表示 被引量:2
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作者 王绍宇 戚飞虎 夏小玲 《中国图象图形学报》 CSCD 北大核心 2008年第10期1898-1901,共4页
针对智能监控的行人轮廓特征提取,先利用MDL shape model得到紧致但能充分表征轮廓几何特征标志点之间的对应关系,再利用椭圆傅里叶分解把行人轮廓表示为一系列不同频率下椭圆傅里叶系数组成的向量,最后得到行人2D+time轮廓的描述向量... 针对智能监控的行人轮廓特征提取,先利用MDL shape model得到紧致但能充分表征轮廓几何特征标志点之间的对应关系,再利用椭圆傅里叶分解把行人轮廓表示为一系列不同频率下椭圆傅里叶系数组成的向量,最后得到行人2D+time轮廓的描述向量。实验结果表明,此方法不但可以在几何上直观地表示行人轮廓,而且大大降低了轮廓向量的维数。 展开更多
关键词 最小描述长度模型 椭圆傅里叶分解 主分量分析 procrustes对齐
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Shape Modeling International 2009(SMI’09)国际会议征稿启事
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《计算机研究与发展》 EI CSCD 北大核心 2008年第11期1954-1954,共1页
关键词 会议征稿 shape modeling International 2009 SMI
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Shape Modeling International 2009(SMI'09)国际会议征稿启事
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《计算机研究与发展》 EI CSCD 北大核心 2008年第9期1516-1516,共1页
关键词 会议征稿 shape modeling International 2009 SMI’09
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Shape Modeling International 2009(SMI'09)国际会议征稿启事
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《计算机辅助设计与图形学学报》 EI CSCD 北大核心 2008年第9期1116-1116,共1页
关键词 会议征稿 shape modeling International 2009 SMI’09
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Active Shape Model of Combining Pca and Ica: Application to Facial Feature Extraction
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作者 邓琳 饶妮妮 王刚 《Journal of Electronic Science and Technology of China》 2006年第2期114-117,共4页
Active Shape Model (ASM) is a powerful statistical tool to extract the facial features of a face image under frontal view. It mainly relies on Principle Component Analysis (PCA) to statistically model the variabil... Active Shape Model (ASM) is a powerful statistical tool to extract the facial features of a face image under frontal view. It mainly relies on Principle Component Analysis (PCA) to statistically model the variability in the training set of example shapes. Independent Component Analysis (ICA) has been proven to be more efficient to extract face features than PCA. In this paper, we combine the PCA and ICA by the consecutive strategy to form a novel ASM. Firstly, an initial model, which shows the global shape variability in the training set, is generated by the PCA-based ASM. And then, the final shape model, which contains more local characters, is established by the ICA-based ASM. Experimental results verify that the accuracy of facial feature extraction is statistically significantly improved by applying the ICA modes after the PCA modes. 展开更多
关键词 facial feature extraction Active shape model (ASM) Principle ComponentAnalysis (PCA) Independent Component Analysis (ICA)
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Active Shape Models Using Scale Invariant Feature Transform
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作者 史勇红 戚飞虎 +1 位作者 栾红霞 吴国荣 《Journal of Shanghai Jiaotong university(Science)》 EI 2007年第6期713-718,共6页
A new active shape models (ASMs) was presented, which is driven by scale invariant feature transform (SIFT) local descriptor instead of normalizing first order derivative profiles in the original formulation, to segme... A new active shape models (ASMs) was presented, which is driven by scale invariant feature transform (SIFT) local descriptor instead of normalizing first order derivative profiles in the original formulation, to segment lung fields from chest radiographs. The modified SIFT local descriptor, more distinctive than the general intensity and gradient features, is used to characterize the image features in the vicinity of each pixel at each resolution level during the segmentation optimization procedure. Experimental results show that the proposed method is more robust and accurate than the original ASMs in terms of an average overlap percentage and average contour distance in segmenting the lung fields from an available public database. 展开更多
关键词 active shape model (ASM) deformable segmentation CHEST RADIOGRAPH scale INVARIANT feature transform (SIFT) local DESCRIPTOR
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Shape model of multi-pass spray deposition plate
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作者 张豪 陈振华 张荻 《中国有色金属学会会刊:英文版》 EI CSCD 1999年第4期682-686,共5页
Multi- pass spray deposition shows apparent advantages in preparing large scale plates with rapid solidification. Shape model is promoted to obtain excellent shape. Three dimensional mathematical models considering mo... Multi- pass spray deposition shows apparent advantages in preparing large scale plates with rapid solidification. Shape model is promoted to obtain excellent shape. Three dimensional mathematical models considering motion of atomization cone and substrate, deposition distance and atomization parameters were used to predict deposited plate’s shape. The results can be used to optimize the process parameters. 展开更多
关键词 SPRAY DEPOSITION MATHEMATICAL models PLATE shape
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Preoperative virtual reduction method for pelvic fractures based on statistical shape models and partial surface data 被引量:1
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作者 Wei Kou Yaoyao He +3 位作者 Xiao Cheng Zhewei Wang Yuan Yang Shaolong Kuang 《Biomimetic Intelligence & Robotics》 EI 2023年第4期67-74,共8页
Virtual reduction is crucial for successful and accurate reduction of pelvic fractures.Various methods have been proposed in this regard.However,not all of them are applicable to every pelvic fracture.Among these meth... Virtual reduction is crucial for successful and accurate reduction of pelvic fractures.Various methods have been proposed in this regard.However,not all of them are applicable to every pelvic fracture.Among these methods,the efficiency and accuracy of the method based on statistical shape models in clinical applications require further improvement.This study proposes a virtual reduction method for pelvic fractures that uses statistical shape models and partial surface data of a broken pelvis.Simulated fracture and clinical case experiments were conducted to validate the accuracy and effectiveness of the proposed method.The simulated fracture experiments yielded an average error of 1.57±0.39 mm and a maximum error of 12.82±3.54 mm.The virtual reduction procedure takes approximately 40 s.Based on three clinical case experiments,the proposed method achieves an acceptable level of accuracy compared with manual reduction by a surgeon.The proposed method offers the advantages of shorter virtual reduction times and satisfactory reduction accuracy.In the future,it will be integrated into the preoperative planning system for pelvic fracture reduction,thereby improving patient outcomes. 展开更多
关键词 Preoperative planning Virtual reduction Statistical shape model Pelvic fractures
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Mesh representation matters:investigating the influence of different mesh features on perceptual and spatial fidelity of deep 3D morphable models
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作者 Robert KOSK Richard SOUTHERN +3 位作者 Lihua YOU Shaojun BIAN Willem KOKKE Greg MAGUIRE 《虚拟现实与智能硬件(中英文)》 EI 2024年第5期383-395,共13页
Background Deep 3D morphable models(deep 3DMMs)play an essential role in computer vision.They are used in facial synthesis,compression,reconstruction and animation,avatar creation,virtual try-on,facial recognition sys... Background Deep 3D morphable models(deep 3DMMs)play an essential role in computer vision.They are used in facial synthesis,compression,reconstruction and animation,avatar creation,virtual try-on,facial recognition systems and medical imaging.These applications require high spatial and perceptual quality of synthesised meshes.Despite their significance,these models have not been compared with different mesh representations and evaluated jointly with point-wise distance and perceptual metrics.Methods We compare the influence of different mesh representation features to various deep 3DMMs on spatial and perceptual fidelity of the reconstructed meshes.This paper proves the hypothesis that building deep 3DMMs from meshes represented with global representations leads to lower spatial reconstruction error measured with L_(1) and L_(2) norm metrics and underperforms on perceptual metrics.In contrast,using differential mesh representations which describe differential surface properties yields lower perceptual FMPD and DAME and higher spatial fidelity error.The influence of mesh feature normalisation and standardisation is also compared and analysed from perceptual and spatial fidelity perspectives.Results The results presented in this paper provide guidance in selecting mesh representations to build deep 3DMMs accordingly to spatial and perceptual quality objectives and propose combinations of mesh representations and deep 3DMMs which improve either perceptual or spatial fidelity of existing methods. 展开更多
关键词 shape modelling Deep 3D morphable models Representation learning Feature engineering Perceptual metrics
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Electron Shape Calculated for the Dual-Charge Dual-Mass Model
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作者 Arlen Young 《Journal of Modern Physics》 CAS 2023年第3期198-207,共10页
A model for the internal structure of the electron using classical physics equations has been previously published by the author. The model employs both positive and negative charges and positive and negative masses. ... A model for the internal structure of the electron using classical physics equations has been previously published by the author. The model employs both positive and negative charges and positive and negative masses. The internal attributes of the electron structure were calculated for both ring and spherical shapes. Further examination of the model reveals an instability for the ring shape. The spherical shape appears to be stable, but relies on tensile or compressive forces of the electron material for stability. The model is modified in this document to eliminate the dependency on material forces. Uniform stability is provided solely by balancing electrical and centrifugal forces. This stability is achieved by slightly elongating the sphere along the spin axis to create a prolate ellipsoid. The semi-major axis of the ellipsoid is the spin axis of the electron, and is calculated to be 1.20% longer than the semi-minor axis, which is the radius of the equator. Although the shape deviates slightly from a perfect sphere, the electric dipole moment is zero. In the author’s previously published document, the attributes of the internal components of the electron, such as charge and mass, were calculated and expressed as ratios to the classically measured values for the composite electron. It is interesting to note that all of these ratios are nearly the same as the inverse of the Fine Structure Constant, with differences of less than 15%. The electron model assumed that the outer surface charge was fixed and uniform. By allowing the charge to be mobile and the shape to have a particular ellipticity, it is shown that the calculated charge and mass ratios for the model can be exactly equal to the Fine Structure Constant and the Constant plus one. The electron radius predicted by the model is 15% greater than the Classical Electron Radius. 展开更多
关键词 Electron shape Classical Electron model Dual-Charge Dual-Mass model Electron Radius Negative Mass Electron Mass Inconsistency Electron Charge Inconsistency Fine Structure Constant
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Detecting winter canola(Brassica napus) phenological stages using an improved shape-model method based on time-series UAV spectral data 被引量:1
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作者 Chao Zhang Zi’ang Xie +5 位作者 Jiali Shang Jiangui Liu Taifeng Dong Min Tang Shaoyuan Feng Huanjie Cai 《The Crop Journal》 SCIE CSCD 2022年第5期1353-1362,共10页
Accurate information about phenological stages is essential for canola field management practices such as irrigation, fertilization, and harvesting. Previous studies in canola phenology monitoring focused mainly on th... Accurate information about phenological stages is essential for canola field management practices such as irrigation, fertilization, and harvesting. Previous studies in canola phenology monitoring focused mainly on the flowering stage, using its apparent structure features and colors. Additional phenological stages have been largely overlooked. The objective of this study was to improve a shape-model method(SMM) for extracting winter canola phenological stages from time-series top-of-canopy reflectance images collected by an unmanned aerial vehicle(UAV). The transformation equation of the SMM was refined to account for the multi-peak features of the temporal dynamics of three vegetation indices(VIs)(NDVI, EVI, and CI). An experiment with various seeding scenarios was conducted, including four different seeding dates and three seeding densities. Three mathematical functions: asymmetric Gaussian function(AGF), Fourier function, and double logistic function, were employed to fit timeseries vegetation indices to extract information about phenological stages. The refined SMM effectively estimated the phenological stages of canola, with a minimum root mean square error(RMSE) of 3.7 days for all phenological stages. The AGF function provided the best fitting performance, as it captured multiple peaks in the growth dynamics characteristics for all seeding date scenarios using four scaling parameters. For the three selected VIs, CIred-edgeachieved the greatest accuracy in estimating the phenological stage dates. This study demonstrates the high potential of the refined SMM for estimating winter canola phenology. 展开更多
关键词 Time-seriesⅥ Asymmetric Gaussian function Phenological stage shape model Remote sensing
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Incorporating shape constraints in generalized additive modelling of the height-diameter relationship for Norway spruce 被引量:3
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作者 Natalya Pya Matthias Schmidt 《Forest Ecosystems》 SCIE CSCD 2016年第2期112-125,共14页
Background: Measurements of tree heights and diameters are essential in forest assessment and modelling. Tree heights are used for estimating timber volume, site index and other important variables related to forest ... Background: Measurements of tree heights and diameters are essential in forest assessment and modelling. Tree heights are used for estimating timber volume, site index and other important variables related to forest growth and yield, succession and carbon budget models. However, the diameter at breast height (dbh) can be more accurately obtained and at lower cost, than total tree height. Hence, generalized height-diameter (h-d) models that predict tree height from dbh, age and other covariates are needed. For a more flexible but biologically plausible estimation of covariate effects we use shape constrained generalized additive models as an extension of existing h-d model approaches. We use causal site parameters such as index of aridity to enhance the generality and causality of the models and to enable predictions under projected changeable climatic conditions. Methods: We develop unconstrained generalized additive models (GAM) and shape constrained generalized additive models (SCAM) for investigating the possible effects of tree-specific parameters such as tree age, relative diameter at breast height, and site-specific parameters such as index of aridity and sum of daily mean temperature during vegetation period, on the h-d relationship of forests in Lower Saxony, Germany. Results: Some of the derived effects, e.g. effects of age, index of aridity and sum of daily mean temperature have significantly non-linear pattern. The need for using SCAM results from the fact that some of the model effects show partially implausible patterns especially at the boundaries of data ranges. The derived model predicts monotonically increasing levels of tree height with increasing age and temperature sum and decreasing aridity and social rank of a tree within a stand, The definition of constraints leads only to marginal or minor decline in the model statistics like AIC An observed structured spatial trend in tree height is modelled via 2-dimensional surface fitting. Conclusions: We demonstrate that the SCAM approach allows optimal regression modelling flexibility similar to the standard GAM but with the additional possibility of defining specific constraints for the model effects. The longitudinal character of the model allows for tree height imputation for the current status of forests but also for future tree height prediction. 展开更多
关键词 Height-diameter curve Norway spruce shape constrained additive models Impact of climate change Varying coefficient models
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Longitudinal height-diameter curves for Norway spruce, Scots pine and silver birch in Norway based on shape constraint additive regression models 被引量:1
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作者 Matthias Schmidt Johannes Breidenbach Rasmus Astrup 《Forest Ecosystems》 SCIE CSCD 2018年第2期109-125,共17页
Background: Generalized height-diameter curves based on a re-parameterized version of the Korf function for Norway spruce (Piceo abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and silver birch (Betula pe... Background: Generalized height-diameter curves based on a re-parameterized version of the Korf function for Norway spruce (Piceo abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth) in Norwa are presented. The Norwegian National Forest Inventory (NFI) is used as data base for estimating the model parameters. The derived models are developed to enable spatially explicit and site sensitive tree height imputatio in forest inventories as well as future tree height predictions in growth and yield scenario simulations. Methods: Generalized additive mixed models (gamm) are employed to detect and quantify potentially non-linear effects of predictor variables. In doing so the quadratic mean diameter serves as longitudinal covariate since stand ag as measured in the NFI, shows only a weak correlation with a stands developmental status in Norwegian forests. Additionally the models can be locally calibrated by predicting random effects if measured height-diameter pairs are available. Based on the model selection of non-constraint models, shape constraint additive models (scare) were fit tc incorporate expert knowledge and intrinsic relationships by enforcing certain effect patterns like monotonicity. Results: Model comparisons demonstrate that the shape constraints lead to only marginal differences in statistical characteristics but ensure reasonable model predictions. Under constant constraints the developed models predict increasing tree heights with decreasing altitude, increasing soil depth and increasing competition pressure of a tree. / two-dimensional spatially structured effect of UTM-coordinates accounts for the potential effects of large scale spatial correlated covariates, which were not at our disposal. The main result of modelling the spatially structured effect is lower tree height prediction for coastal sites and with increasing latitude. The quadratic mean diameter affects both the level and the slope of the height-diameter curve and both effects are positive. Conclusions: In this investigation it is assumed that model effects in additive modelling of height-diameter curves which are unfeasible and too wiggly from an expert point of view are a result of quantitatively or qualitatively limited data bases. However, this problem can be regarded not to be specific to our investigation but more general since growth and yield data that are balanced over the whole data range with respect to all combinations of predictor variables are exceptional cases. Hence, scare may provide methodological improvements in several applications by combining the flexibility of additive models with expert knowledge. 展开更多
关键词 Height-diameter curve Norway spruce Scots pine Silver birch Norwegian national forest inventory shape constrained additive models
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Modeling of the Shape Forming of Composite Roll 被引量:2
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作者 Chengsong CUI, Zhenyu LI, Fuyang CAO and Qingchun LI (School of Materials Science and Engineering, Harbin Institute of Technology, 150001, China) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2000年第3期337-340,共4页
A shape modeling of spray formed composite roll, which is utilized to predict the shape and dimension of roll during spray forming process, is developed in this paper. The influences of the principal spray forming par... A shape modeling of spray formed composite roll, which is utilized to predict the shape and dimension of roll during spray forming process, is developed in this paper. The influences of the principal spray forming parameters, such as the spatial distribution of melt mass flux, spray distance, rotating and translating speeds of substrate bar etc. , on the geometry and dimension of spray formed product were investigated. 展开更多
关键词 modeling of the shape Forming of Composite Roll
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Modeling the keyhole shape and dimension in plasma arc welding 被引量:3
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作者 霍玉双 武传松 《China Welding》 EI CAS 2009年第2期17-20,共4页
It is of great significance to model the keyhole shape and dimensions to optimize the plasma arc welding process parameters. In this study, through employing a combined volumetric heat source mode, the weld pool in ke... It is of great significance to model the keyhole shape and dimensions to optimize the plasma arc welding process parameters. In this study, through employing a combined volumetric heat source mode, the weld pool in keyhole plasma arc welding is determined firstly, and then the dynamic force-balance condition on the interface between the plasma jet and the molten metal is dealt with in describing the keyhole formation inside the weld pool. The effects of welding current on the shape and size of keyhole are numerically analyzed. The sharp transformation from a partial keyhole to a full-penetration keyhole is quantitatively demonstrated. 展开更多
关键词 keyhole shape plasma arc welding modelING
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Improved shape hardening function for bounding surface model for cohesive soils 被引量:1
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作者 Andrés Nieto-Leal Victor N.Kaliakin 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2014年第4期328-337,共10页
A shape hardening function is developed that improves the predictive capabilities of the generalized bounding surface model for cohesive soils, especially when applied to overconsolidated specimens. This improvement i... A shape hardening function is developed that improves the predictive capabilities of the generalized bounding surface model for cohesive soils, especially when applied to overconsolidated specimens. This improvement is realized without any changes to the simple elliptical shape of the bounding surface, and actually reduces the number of parameters associated with the model by one. 展开更多
关键词 Constitutive model Bounding surface plasticity shape hardening function Clay
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DEFICIENT INFORMATION MODELING OF MECHANICAL PRODUCTS FOR CONCEPTUAL SHAPE DESIGN 被引量:3
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作者 Liu Jihong Shu Huilin CAD Center,Huazhong University of Science and Technology,Wuhan 430074,China 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2002年第1期1-5,26,共6页
In allusion to the deficient feature of product information in conceptualdesign, a framework of deficient information modeling for conceptual shape design is put forward,which includes qualitative shape modeling (a qu... In allusion to the deficient feature of product information in conceptualdesign, a framework of deficient information modeling for conceptual shape design is put forward,which includes qualitative shape modeling (a qualitative solid model), uncertain shape modeling (anuncertain relation model) and imprecise shape modeling (an imprecise region model). In theframework, the qualitative solid model is the core, which represents qualitatively (using symbols)the conceptual shapes of mechanical products. The uncertain relation model regarding domainrelations as objects and the imprecise region model regarding domains as objects are used to dealwith the uncertain and imprecise issues respectively, which arise from qualitative shape modeling orexist in product information itself. 展开更多
关键词 Conceptual shape design Qualitative solid model Spatial cognition
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Modeling Real Objects for Kansei-based Shape Retrieval 被引量:2
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作者 Yukihiro Koda Ichi Kanaya Kosuke Sato 《International Journal of Automation and computing》 EI 2007年第1期14-17,共4页
A large number of 3D models are created on computers and available for networks. Some content-based retrieval technologies are indispensable to find out particular data from such anonymous datasets. Though several sha... A large number of 3D models are created on computers and available for networks. Some content-based retrieval technologies are indispensable to find out particular data from such anonymous datasets. Though several shape retrieval technologies have been developed, little attention has been given to the points on human's sense and impression (as known as Kansei) in the conventional techniques, In this paper, the authors propose a novel method of shape retrieval based on shape impression of human's Kansei. The key to the method is the Gaussian curvature distribution from 3D models as features for shape retrieval. Then it classifies the 3D models by extracted feature and measures similarity among models in storage. 展开更多
关键词 shape retrieval Kansei engineering modeling of real object.
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