Fracture surface contour study is one of the important requirements for characterization and evaluation of the microstructure of rocks.Based on the improved cube covering method and the 3D contour digital reconstructi...Fracture surface contour study is one of the important requirements for characterization and evaluation of the microstructure of rocks.Based on the improved cube covering method and the 3D contour digital reconstruction model,this study proposes a quantitative microstructure characterization method combining the roughness evaluation index and the 3D fractal dimension to study the change rule of the fracture surface morphology after blasting.This method was applied and validated in the study of the fracture microstructure of the rock after blasting.The results show that the fracture morphology characteristics of the 3D contour digital reconstruction model have good correlation with the changes of the blasting action.The undulation rate of the three-dimensional surface profile of the rock is more prone to dramatic rise and dramatic fall morphology.In terms of tilting trend,the tilting direction also shows gradual disorder,with the tilting angle increasing correspondingly.All the roughness evaluation indexes of the rock fissure surface after blasting show a linear and gradually increasing trend as the distance to the bursting center increases;the difference between the two-dimensional roughness evaluation indexes and the three-dimensional ones of the same micro-area rock samples also becomes increasingly larger,among which the three-dimensional fissure roughness coefficient JRC and the surface roughness ratio Rs display better correlation.Compared with the linear fitting formula of the power function relationship,the three-dimensional fractal dimension of the postblast fissure surface is fitted with the values of JRC and Rs,which renders higher correlation coefficients,and the degree of linear fitting of JRC to the three-dimensional fractal dimension is higher.The fractal characteristics of the blast-affected region form a unity with the three-dimensional roughness evaluation of the fissure surface.展开更多
Noise contours are used to describe the extent of airport noise pollution and to plan land use around airports. The L WECPN(weighted equivalent continuous perceive noise level) recommended by ICAO(International Civ...Noise contours are used to describe the extent of airport noise pollution and to plan land use around airports. The L WECPN(weighted equivalent continuous perceive noise level) recommended by ICAO(International Civil Aviation Organization) is adopted as airport noise rating parameter in this paper. With the help of various mathematical models in the software Surfer, noise contours can be drawn automatically by the completed program in Visual C++ Code. Corrections for thrust, velocity, atmospheric temperature, humidity and lateral ground attenuation are also considered in the new method, which can improve the efficiency of drawing contours. An example of its use for drawing noise contours of an airport in Zhejiang Province of China is proposed and the predictions and the measurements show agreements well.展开更多
Four distinct litho-tectonic belts (zones) in the Yinshan area, North China, were identified by pressure-temperature contours and litho-tectonic features, such as the Sanggan granulite belt, Jining metasedimentary bel...Four distinct litho-tectonic belts (zones) in the Yinshan area, North China, were identified by pressure-temperature contours and litho-tectonic features, such as the Sanggan granulite belt, Jining metasedimentary belt, Wulashan-Daqingshan front tectonic zone and Se' eratengshan belt. This area witnessed two important thermo-tectonic events. The older one is c. 2.5 Ga while the younger one c. 1.9 Ga. The Se' ertengshan Neoarchaean terrane features a clockwise PT path with the decompression ranging from > 1500 MPa to 800–1000 MPa in the Se' ertengshan belt, which implies an island arc setting. The Sanggan belt is a Mesoarchaean microcontinent reworked by Neoarchaean magma underplating, which shows an counterclockwise PT path. During the Palaeoproterozoic period, two Archaean continent (arc) collided. The Archaean basement of the Sanggan and Wulashan-Daqingshan belts overthrust northwards, the PTt paths of basement show a decompression from 1000–1200 MPa to 500–700 MPa. The PT paths of the Jining and Erdaowa Groups show different PTt paths: the former shows counterclockwise while the latter clockwise, which indicates that the Jining and Erdaowa groups formed in different thermo-tectonic settings.展开更多
A new method for constructing contours from complicated terrain elevation grids containing invalid data is put forward. By using this method, the topological consistency of contours in groups can be maintained effecti...A new method for constructing contours from complicated terrain elevation grids containing invalid data is put forward. By using this method, the topological consistency of contours in groups can be maintained effectively and the contours can be drawn smoothly based on boundaries pre-searching and local correction. An experimental example is given to demonstrate that the contours constructed by this method are of good quality.展开更多
MGAC (Motion Geometric Active Contours), a new variational framework of geometric active contours to track multiple nonrigid moving objects in the clutter background in image sequences is presented. This framework, in...MGAC (Motion Geometric Active Contours), a new variational framework of geometric active contours to track multiple nonrigid moving objects in the clutter background in image sequences is presented. This framework, incorporating with the motion edge information, consists of motion detection and tracking stages. At the motion detection stage, the motion edge map provides an approximate edge map of the moving objects. Then, a tracking stage, merely using the static edge information, is considered to improve the motion detection result. Force field regularization method is used to extend the capture range of the edge attraction force field in both stages. Experiments demonstrate that the proposed framework is valid for tracking multiple nonrigid objects in the clutter background.展开更多
Rising sea levels due to global warming and climate change impact may prove a disaster for small islands. Accurate DEM （digital elevation model） can help to understand SLR （sea level rise） impact, coastal zones fl...Rising sea levels due to global warming and climate change impact may prove a disaster for small islands. Accurate DEM （digital elevation model） can help to understand SLR （sea level rise） impact, coastal zones flooding risks assessment and hydrological attributes modeling and extraction. Currently, DEMs are available from several different sources using active and passive remote sensing systems. This research compares absolute surface heights accuracies retrieved from three independent DEMs datasets. The Shuttle Radar Topographic Mission （SRTM-V4.1） and the Advanced Space borne Thermal Emission and Reflection Radiometer （ASTER-V2.1） with 30-m pixel size, and a DEM-5 of 5-m spatial resolution generated from high topographic contour lines map at scale of 1：5,000 using simple Kriging interpolation method. Moreover, topographic attributes （slope and aspect） have been retrieved and compared. For the elevations validation purposes, a dataset of 400 GCPs uniformly distributed over the study site were used. These were measured using a DGPS assuring ± 1 and ± 2 cm accuracies, respectively, for planimerry and altimetry. The obtained results show that globally the landscape scale plays an important role in the selection of the DEM pixel size, which must reflect the real topographic attributes. Indeed, the derived DEM-5 from high topographic contours map （1：5,000） using simple Kriging exhibit the best accuracy of ±0.65 m which is less than the tolerance or the total error （±0.78 m） calculated based on errors sources propagation. Then, the results show an accuracy of ± 3.00 m for SRTM-V4.1 which is less than the absolute vertical height accuracy （±5.6 m） advocated by NASA for African continent and Middle-East regions. As well, the achieved ASTER accuracy was ± 8.40 m compared to the estimated error （±17.01 m） by USGS and JAXA. Obviously, high spatial resolution and accurate DEM-5 is a crucial requirement to simulate and evaluate costal zones inundation under different SLR and storm flow scenarios for small islands. Decidedly, the elevation of small islands with topographic features not higher than 134 m can be estimated using SRTM-V4.1 with relatively acceptable accuracy. Whereas, this DEM is not significantly consistent for accurate SLR scenarios simulations. Without doubt, ASTER-V2.1 DEM was an excellent alternative compared to SRTM with 90-m pixel size, but actually with SRTM-V4.1 full resolution （30-m） ASTER-V2.1 will likely see its limited uses in geosciences applications. Indeed, ASTER is not providing accurate information to simulate the impact of SLR scenarios on small islands.展开更多
In this paper, we propose a fast centerline extraction method to be used for gradient and direction vector flow of active contours. The gradient and direction vector flow is a recently reported active contour model ca...In this paper, we propose a fast centerline extraction method to be used for gradient and direction vector flow of active contours. The gradient and direction vector flow is a recently reported active contour model capable of significantly improving the image segmentation performance especially for complex object shape, by seamlessly integrating gradient vector flow and prior directional information. Since the prior directional information is provided by manual line drawing, it can be inconvenient for inexperienced users who might have difficulty in finding the best place to draw the directional lines to achieve the best segmentation performance. This paper describes a method to overcome this problem by automatically extracting centerlines to guide the users for providing the right directional information. Experimental results on synthetic and real images demonstrate the feasibility of the proposed method.展开更多
This paper explores brain CT slices segmentation technique and some related problems, including contours segmentation algorithms, edge detector, algorithm evaluation and experimental results. This article describes a ...This paper explores brain CT slices segmentation technique and some related problems, including contours segmentation algorithms, edge detector, algorithm evaluation and experimental results. This article describes a method for contour-based segmentation of anatomical structures in 3D medical data sets. With this method, the user manually traces one or more 2D contours of an anatomical structure of interest on parallel planes arbitrarily cutting the data set. The experimental results showes the segmentation based on 3D brain volume and 2D CT slices. The main creative contributions in this paper are: (1) contours segmentation algorithm; (2) edge detector; (3) algorithm evaluation.展开更多
Three dimensional digitization of human head is desired in many applications. In this paper, an information fusion based scheme is presented to obtain 3-D information of human head. Structured light technology is empl...Three dimensional digitization of human head is desired in many applications. In this paper, an information fusion based scheme is presented to obtain 3-D information of human head. Structured light technology is employed to measure depth. For the special reflection areas,in which the structured light stripe can not be detected directly, the shape of the structured light stripe can be calculated from the corresponding contour. By fusing the information of structured light and the contours, the problem of reflectance influence is solved, and the whole shape of head,including hair area, can be obtained. Some good results are obtained.展开更多
A storage-efficient reconstruction framework for cartographic planar contours is developed.With a smaller number of control points,we aim to calculate the area and perimeter as well as to reconstruct a smooth curve.Th...A storage-efficient reconstruction framework for cartographic planar contours is developed.With a smaller number of control points,we aim to calculate the area and perimeter as well as to reconstruct a smooth curve.The input data forms an oriented contour,each control point of which consists of three values:the Cartesian coordinates(x,y)and tangent angleθ.Two types of interpolation methods are developed,one of which is based on an arc spline while the other one is on a cubic Hermite spline.The arc spline-based method reconstructs a G1 continuous curve,with which the exact area and perimeter can be calculated.The benefit of using the Hermite spline-based method is that it can achieve G2 continuity on most control points and can obtain the exact area,whereas the resulting perimeter is approximate.In a numerical experiment for analytically defined curves,more accurate computation of the area and perimeter was achieved with a smaller number of control points.In another experiment using a digital elevation model data,the reconstructed contours were smoother than those by a conventional method.展开更多
Gradient vector flow （GVF） is an effective external force for active contours, but its iso- tropic nature handicaps its performance. The recently proposed gradient vector flow in the normal direction （NGVF） is ani...Gradient vector flow （GVF） is an effective external force for active contours, but its iso- tropic nature handicaps its performance. The recently proposed gradient vector flow in the normal direction （NGVF） is anisotropic since it only keeps the diffusion along the normal direction of the isophotes; however, it has difficulties forcing a snake into long, thin boundary indentations. In this paper, a novel external force for active contours called normally generalized gradient vector flow （NGGVF） is proposed, which generalizes the NGVF formulation to include two spatially varying weighting functions. Consequently, the proposed NGGVF snake is anisotropic and would improve ac- tive contour convergence into long, thin boundary indentations while maintaining other desirable properties of the NGVF snake, such as enlarged capture range, initialization insensitivity and good convergence at concavities. The advantages on synthetic and real images are demonstrated.展开更多
Extracting building contours from aerial images is a fundamental task in remote sensing.Current building extraction methods cannot accurately extract building contour information and have errors in extracting small-sc...Extracting building contours from aerial images is a fundamental task in remote sensing.Current building extraction methods cannot accurately extract building contour information and have errors in extracting small-scale buildings.This paper introduces a novel dense feature iterative(DFI)fusion network,denoted as DFINet,for extracting building contours.The network uses a DFI decoder to fuse semantic information at different scales and learns the building contour knowledge,producing the last features through iterative fusion.The dense feature fusion(DFF)module combines features at multiple scales.We employ the contour reconstruction(CR)module to access the final predictions.Extensive experiments validate the effectiveness of the DFINet on two different remote sensing datasets,INRIA aerial image dataset and Wuhan University(WHU)building dataset.On the INRIA aerial image dataset,our method achieves the highest intersection over union(IoU),overall accuracy(OA)and F 1 scores compared to other state-of-the-art methods.展开更多
Contour is an important pattern descriptor in image processing and particularly in region description, registration and length estimation. In many applications where contour is used, a good segmentation and an efficie...Contour is an important pattern descriptor in image processing and particularly in region description, registration and length estimation. In many applications where contour is used, a good segmentation and an efficient smoothing method are needed. In X-ray images, such as mammograms, where object edge is not clearly discernible, estimating the object’s contour may yield substantial shift along the boundary due to noise or segmentation drawbacks. An appropriate smoothing is therefore required to reduce these effects. In this paper, an approach based on local adaptive threshold segmentation to extract contour and a new smoothing approach founded on Fourier descriptors are introduced. The experimental results of extraction obtained from a set of mammograms and compared with the breast regions delineated by radiologists yielded a percent overlap area of 98.7% ± 0.9% with false positive and negative rates of 0.36 ± 0.74 and 0.93 ± 0.44 respectively. The proposed method was tested on a set of images and improved the accuracy, leading to an average error of less than one pixel.展开更多
Moving object segmentation is one of the most challenging issues in computer vision. In this paper, we propose a new algorithm for static camera foreground segmentation. It combines Gaussian mixture model （GMM） and ...Moving object segmentation is one of the most challenging issues in computer vision. In this paper, we propose a new algorithm for static camera foreground segmentation. It combines Gaussian mixture model （GMM） and active contours method, and produces much better results than conventional background subtraction methods. It formulates foreground segmentation as an energy minimization problem and minimizes the energy function using curve evolution method. Our algorithm integrates the GMM background model, shadow elimination term and curve evolution edge stopping term into energy function. It achieves more accurate segmentation than existing methods of the same type. Promising results on real images demonstrate the potential of the presented method.展开更多
The strategy of modeling the control mechanism for generating F0 contour of speech signal is studied in this paper. Based on some dynamic characteristics of vocal cord strain, the complex laryngeal mechanism relative ...The strategy of modeling the control mechanism for generating F0 contour of speech signal is studied in this paper. Based on some dynamic characteristics of vocal cord strain, the complex laryngeal mechanism relative to local F0 regulation is simplified to be a feasible physical model. Furthermore, a model function is deduced as the control mechanism for the generation process of local rise-fall patterns, and two kinds of basic feature patterns result with so called rise-fall commands defined by model parameters. on the logarithmic scale of F0 versus time the local characteristics of an F0 contour are approximated by the sum of these patterns generated by appropriate commands. The experimenial results in analyzing and synthesizing the F0 contours of spoken Chinese utterances indicate that the observed F0 contours can be always approximated well by the model, and a good correlation exists between some model parameters and the transition duration of local F0 rising or falling. The model lays a foundation for Chinese F0 contour synthesis by rule.展开更多
By utilizing the classical turning point of the electron movement, we have defined and computed the mo-lecular intrinsic characteristic contour (MICC) via the com-bination of the ab initio quantum chemistry computatio...By utilizing the classical turning point of the electron movement, we have defined and computed the mo-lecular intrinsic characteristic contour (MICC) via the com-bination of the ab initio quantum chemistry computational method with the ionization potential measured by photo-electron spectroscopy experiment. In this paper, we calcu-lated the MICCs of several small organic molecules contain-ing oxygen atom for the first time. The three-dimensional pictures have been drawn, by performing a large number of calculations. The analysis on some characterized cross-sec-tions of the MICC can provide atomic spatial changing information in the process of forming a molecule.展开更多
The molecular intrinsic characteristic contour (MICC) is defined based on the clas-sical turning point of electron movement in a molecule. Three typical organic molecules, i.e. methane, methanol and formic acid, were ...The molecular intrinsic characteristic contour (MICC) is defined based on the clas-sical turning point of electron movement in a molecule. Three typical organic molecules, i.e. methane, methanol and formic acid, were employed as examples for detailed introduction of our method. Investigations on the cross-sections of MICC provide important information about atomic size changing in the process of forming molecules. The electron density distributions on the MICCs of these molecules were calculated and shown for the first time. Results showed that the electron density distribution on the MICC correlates closely with molecular chemical properties, and it provides a new insight into molecular boundary.展开更多
The H and O isotope compositions of 41 whole rocks and 24 separated minerals of theNianzishan miarolitic alkaline granite and 3 local meteoric water samples have been meas-ured. The results indicate that the meteoric-...The H and O isotope compositions of 41 whole rocks and 24 separated minerals of theNianzishan miarolitic alkaline granite and 3 local meteoric water samples have been meas-ured. The results indicate that the meteoric-hydrothermal convective system might have beendeveloped in this stock. The distributions of δ^(18)O values of whole-rock samples formed anapproximateIy δ^(18)O contours with the characteristic of kighest values in the midst and de-creasing toward the outer zones. The water/rock ratio (W/R) contours were also calculated.This phenomenon might have common significance for stocks or plutons.展开更多
基金National Key Research and Development Program of China,Grant/Award Number:2021YFC2902103National Natural Science Foundation of China,Grant/Award Number:51934001Fundamental Research Funds for the Central Universities,Grant/Award Number:2023JCCXLJ02。
文摘Fracture surface contour study is one of the important requirements for characterization and evaluation of the microstructure of rocks.Based on the improved cube covering method and the 3D contour digital reconstruction model,this study proposes a quantitative microstructure characterization method combining the roughness evaluation index and the 3D fractal dimension to study the change rule of the fracture surface morphology after blasting.This method was applied and validated in the study of the fracture microstructure of the rock after blasting.The results show that the fracture morphology characteristics of the 3D contour digital reconstruction model have good correlation with the changes of the blasting action.The undulation rate of the three-dimensional surface profile of the rock is more prone to dramatic rise and dramatic fall morphology.In terms of tilting trend,the tilting direction also shows gradual disorder,with the tilting angle increasing correspondingly.All the roughness evaluation indexes of the rock fissure surface after blasting show a linear and gradually increasing trend as the distance to the bursting center increases;the difference between the two-dimensional roughness evaluation indexes and the three-dimensional ones of the same micro-area rock samples also becomes increasingly larger,among which the three-dimensional fissure roughness coefficient JRC and the surface roughness ratio Rs display better correlation.Compared with the linear fitting formula of the power function relationship,the three-dimensional fractal dimension of the postblast fissure surface is fitted with the values of JRC and Rs,which renders higher correlation coefficients,and the degree of linear fitting of JRC to the three-dimensional fractal dimension is higher.The fractal characteristics of the blast-affected region form a unity with the three-dimensional roughness evaluation of the fissure surface.
文摘Noise contours are used to describe the extent of airport noise pollution and to plan land use around airports. The L WECPN(weighted equivalent continuous perceive noise level) recommended by ICAO(International Civil Aviation Organization) is adopted as airport noise rating parameter in this paper. With the help of various mathematical models in the software Surfer, noise contours can be drawn automatically by the completed program in Visual C++ Code. Corrections for thrust, velocity, atmospheric temperature, humidity and lateral ground attenuation are also considered in the new method, which can improve the efficiency of drawing contours. An example of its use for drawing noise contours of an airport in Zhejiang Province of China is proposed and the predictions and the measurements show agreements well.
文摘Four distinct litho-tectonic belts (zones) in the Yinshan area, North China, were identified by pressure-temperature contours and litho-tectonic features, such as the Sanggan granulite belt, Jining metasedimentary belt, Wulashan-Daqingshan front tectonic zone and Se' eratengshan belt. This area witnessed two important thermo-tectonic events. The older one is c. 2.5 Ga while the younger one c. 1.9 Ga. The Se' ertengshan Neoarchaean terrane features a clockwise PT path with the decompression ranging from > 1500 MPa to 800–1000 MPa in the Se' ertengshan belt, which implies an island arc setting. The Sanggan belt is a Mesoarchaean microcontinent reworked by Neoarchaean magma underplating, which shows an counterclockwise PT path. During the Palaeoproterozoic period, two Archaean continent (arc) collided. The Archaean basement of the Sanggan and Wulashan-Daqingshan belts overthrust northwards, the PTt paths of basement show a decompression from 1000–1200 MPa to 500–700 MPa. The PT paths of the Jining and Erdaowa Groups show different PTt paths: the former shows counterclockwise while the latter clockwise, which indicates that the Jining and Erdaowa groups formed in different thermo-tectonic settings.
文摘A new method for constructing contours from complicated terrain elevation grids containing invalid data is put forward. By using this method, the topological consistency of contours in groups can be maintained effectively and the contours can be drawn smoothly based on boundaries pre-searching and local correction. An experimental example is given to demonstrate that the contours constructed by this method are of good quality.
文摘MGAC (Motion Geometric Active Contours), a new variational framework of geometric active contours to track multiple nonrigid moving objects in the clutter background in image sequences is presented. This framework, incorporating with the motion edge information, consists of motion detection and tracking stages. At the motion detection stage, the motion edge map provides an approximate edge map of the moving objects. Then, a tracking stage, merely using the static edge information, is considered to improve the motion detection result. Force field regularization method is used to extend the capture range of the edge attraction force field in both stages. Experiments demonstrate that the proposed framework is valid for tracking multiple nonrigid objects in the clutter background.
文摘Rising sea levels due to global warming and climate change impact may prove a disaster for small islands. Accurate DEM （digital elevation model） can help to understand SLR （sea level rise） impact, coastal zones flooding risks assessment and hydrological attributes modeling and extraction. Currently, DEMs are available from several different sources using active and passive remote sensing systems. This research compares absolute surface heights accuracies retrieved from three independent DEMs datasets. The Shuttle Radar Topographic Mission （SRTM-V4.1） and the Advanced Space borne Thermal Emission and Reflection Radiometer （ASTER-V2.1） with 30-m pixel size, and a DEM-5 of 5-m spatial resolution generated from high topographic contour lines map at scale of 1：5,000 using simple Kriging interpolation method. Moreover, topographic attributes （slope and aspect） have been retrieved and compared. For the elevations validation purposes, a dataset of 400 GCPs uniformly distributed over the study site were used. These were measured using a DGPS assuring ± 1 and ± 2 cm accuracies, respectively, for planimerry and altimetry. The obtained results show that globally the landscape scale plays an important role in the selection of the DEM pixel size, which must reflect the real topographic attributes. Indeed, the derived DEM-5 from high topographic contours map （1：5,000） using simple Kriging exhibit the best accuracy of ±0.65 m which is less than the tolerance or the total error （±0.78 m） calculated based on errors sources propagation. Then, the results show an accuracy of ± 3.00 m for SRTM-V4.1 which is less than the absolute vertical height accuracy （±5.6 m） advocated by NASA for African continent and Middle-East regions. As well, the achieved ASTER accuracy was ± 8.40 m compared to the estimated error （±17.01 m） by USGS and JAXA. Obviously, high spatial resolution and accurate DEM-5 is a crucial requirement to simulate and evaluate costal zones inundation under different SLR and storm flow scenarios for small islands. Decidedly, the elevation of small islands with topographic features not higher than 134 m can be estimated using SRTM-V4.1 with relatively acceptable accuracy. Whereas, this DEM is not significantly consistent for accurate SLR scenarios simulations. Without doubt, ASTER-V2.1 DEM was an excellent alternative compared to SRTM with 90-m pixel size, but actually with SRTM-V4.1 full resolution （30-m） ASTER-V2.1 will likely see its limited uses in geosciences applications. Indeed, ASTER is not providing accurate information to simulate the impact of SLR scenarios on small islands.
文摘In this paper, we propose a fast centerline extraction method to be used for gradient and direction vector flow of active contours. The gradient and direction vector flow is a recently reported active contour model capable of significantly improving the image segmentation performance especially for complex object shape, by seamlessly integrating gradient vector flow and prior directional information. Since the prior directional information is provided by manual line drawing, it can be inconvenient for inexperienced users who might have difficulty in finding the best place to draw the directional lines to achieve the best segmentation performance. This paper describes a method to overcome this problem by automatically extracting centerlines to guide the users for providing the right directional information. Experimental results on synthetic and real images demonstrate the feasibility of the proposed method.
文摘This paper explores brain CT slices segmentation technique and some related problems, including contours segmentation algorithms, edge detector, algorithm evaluation and experimental results. This article describes a method for contour-based segmentation of anatomical structures in 3D medical data sets. With this method, the user manually traces one or more 2D contours of an anatomical structure of interest on parallel planes arbitrarily cutting the data set. The experimental results showes the segmentation based on 3D brain volume and 2D CT slices. The main creative contributions in this paper are: (1) contours segmentation algorithm; (2) edge detector; (3) algorithm evaluation.
基金Supported by the National Natural Science Foundation of China(69775022) and 863 Programme of China(863-306-ZT04-06-3)
文摘Three dimensional digitization of human head is desired in many applications. In this paper, an information fusion based scheme is presented to obtain 3-D information of human head. Structured light technology is employed to measure depth. For the special reflection areas,in which the structured light stripe can not be detected directly, the shape of the structured light stripe can be calculated from the corresponding contour. By fusing the information of structured light and the contours, the problem of reflectance influence is solved, and the whole shape of head,including hair area, can be obtained. Some good results are obtained.
文摘A storage-efficient reconstruction framework for cartographic planar contours is developed.With a smaller number of control points,we aim to calculate the area and perimeter as well as to reconstruct a smooth curve.The input data forms an oriented contour,each control point of which consists of three values:the Cartesian coordinates(x,y)and tangent angleθ.Two types of interpolation methods are developed,one of which is based on an arc spline while the other one is on a cubic Hermite spline.The arc spline-based method reconstructs a G1 continuous curve,with which the exact area and perimeter can be calculated.The benefit of using the Hermite spline-based method is that it can achieve G2 continuity on most control points and can obtain the exact area,whereas the resulting perimeter is approximate.In a numerical experiment for analytically defined curves,more accurate computation of the area and perimeter was achieved with a smaller number of control points.In another experiment using a digital elevation model data,the reconstructed contours were smoother than those by a conventional method.
基金Supported by the National Natural Science Foundation of China(60805004)the State Key Lab of Space Medicine Fundamen-tals and Application(SMFA09A16)
文摘Gradient vector flow （GVF） is an effective external force for active contours, but its iso- tropic nature handicaps its performance. The recently proposed gradient vector flow in the normal direction （NGVF） is anisotropic since it only keeps the diffusion along the normal direction of the isophotes; however, it has difficulties forcing a snake into long, thin boundary indentations. In this paper, a novel external force for active contours called normally generalized gradient vector flow （NGGVF） is proposed, which generalizes the NGVF formulation to include two spatially varying weighting functions. Consequently, the proposed NGGVF snake is anisotropic and would improve ac- tive contour convergence into long, thin boundary indentations while maintaining other desirable properties of the NGVF snake, such as enlarged capture range, initialization insensitivity and good convergence at concavities. The advantages on synthetic and real images are demonstrated.
基金National Natural Science Foundation of China(No.61903078)Fundamental Research Funds for the Central Universities,China(No.2232021A-10)+1 种基金Shanghai Sailing Program,China(No.22YF1401300)Natural Science Foundation of Shanghai,China(No.20ZR1400400)。
文摘Extracting building contours from aerial images is a fundamental task in remote sensing.Current building extraction methods cannot accurately extract building contour information and have errors in extracting small-scale buildings.This paper introduces a novel dense feature iterative(DFI)fusion network,denoted as DFINet,for extracting building contours.The network uses a DFI decoder to fuse semantic information at different scales and learns the building contour knowledge,producing the last features through iterative fusion.The dense feature fusion(DFF)module combines features at multiple scales.We employ the contour reconstruction(CR)module to access the final predictions.Extensive experiments validate the effectiveness of the DFINet on two different remote sensing datasets,INRIA aerial image dataset and Wuhan University(WHU)building dataset.On the INRIA aerial image dataset,our method achieves the highest intersection over union(IoU),overall accuracy(OA)and F 1 scores compared to other state-of-the-art methods.
文摘Contour is an important pattern descriptor in image processing and particularly in region description, registration and length estimation. In many applications where contour is used, a good segmentation and an efficient smoothing method are needed. In X-ray images, such as mammograms, where object edge is not clearly discernible, estimating the object’s contour may yield substantial shift along the boundary due to noise or segmentation drawbacks. An appropriate smoothing is therefore required to reduce these effects. In this paper, an approach based on local adaptive threshold segmentation to extract contour and a new smoothing approach founded on Fourier descriptors are introduced. The experimental results of extraction obtained from a set of mammograms and compared with the breast regions delineated by radiologists yielded a percent overlap area of 98.7% ± 0.9% with false positive and negative rates of 0.36 ± 0.74 and 0.93 ± 0.44 respectively. The proposed method was tested on a set of images and improved the accuracy, leading to an average error of less than one pixel.
基金Supported by National Basic Research Program of China (Grant No.2006CB303105)the Chinese Ministry of Education Innovation Team Fund Project (Grant No.IRT0707)+3 种基金the National Natural Science Foundation of China (Grant Nos.60673109 and 60801053)Beijing Excellent Doctoral Thesis Program (Grant No. YB20081000401)Beijing Municipal Natural Science Foundation (Grant No.4082025)Doctoral Foundation of China (Grant No.20070004037)
文摘Moving object segmentation is one of the most challenging issues in computer vision. In this paper, we propose a new algorithm for static camera foreground segmentation. It combines Gaussian mixture model （GMM） and active contours method, and produces much better results than conventional background subtraction methods. It formulates foreground segmentation as an energy minimization problem and minimizes the energy function using curve evolution method. Our algorithm integrates the GMM background model, shadow elimination term and curve evolution edge stopping term into energy function. It achieves more accurate segmentation than existing methods of the same type. Promising results on real images demonstrate the potential of the presented method.
文摘The strategy of modeling the control mechanism for generating F0 contour of speech signal is studied in this paper. Based on some dynamic characteristics of vocal cord strain, the complex laryngeal mechanism relative to local F0 regulation is simplified to be a feasible physical model. Furthermore, a model function is deduced as the control mechanism for the generation process of local rise-fall patterns, and two kinds of basic feature patterns result with so called rise-fall commands defined by model parameters. on the logarithmic scale of F0 versus time the local characteristics of an F0 contour are approximated by the sum of these patterns generated by appropriate commands. The experimenial results in analyzing and synthesizing the F0 contours of spoken Chinese utterances indicate that the observed F0 contours can be always approximated well by the model, and a good correlation exists between some model parameters and the transition duration of local F0 rising or falling. The model lays a foundation for Chinese F0 contour synthesis by rule.
文摘By utilizing the classical turning point of the electron movement, we have defined and computed the mo-lecular intrinsic characteristic contour (MICC) via the com-bination of the ab initio quantum chemistry computational method with the ionization potential measured by photo-electron spectroscopy experiment. In this paper, we calcu-lated the MICCs of several small organic molecules contain-ing oxygen atom for the first time. The three-dimensional pictures have been drawn, by performing a large number of calculations. The analysis on some characterized cross-sec-tions of the MICC can provide atomic spatial changing information in the process of forming a molecule.
基金the National Natural Science Foundation of China(Grant No.20073018).
文摘The molecular intrinsic characteristic contour (MICC) is defined based on the clas-sical turning point of electron movement in a molecule. Three typical organic molecules, i.e. methane, methanol and formic acid, were employed as examples for detailed introduction of our method. Investigations on the cross-sections of MICC provide important information about atomic size changing in the process of forming molecules. The electron density distributions on the MICCs of these molecules were calculated and shown for the first time. Results showed that the electron density distribution on the MICC correlates closely with molecular chemical properties, and it provides a new insight into molecular boundary.
基金Project supported by the National Natural Science Foundation of China.
文摘The H and O isotope compositions of 41 whole rocks and 24 separated minerals of theNianzishan miarolitic alkaline granite and 3 local meteoric water samples have been meas-ured. The results indicate that the meteoric-hydrothermal convective system might have beendeveloped in this stock. The distributions of δ^(18)O values of whole-rock samples formed anapproximateIy δ^(18)O contours with the characteristic of kighest values in the midst and de-creasing toward the outer zones. The water/rock ratio (W/R) contours were also calculated.This phenomenon might have common significance for stocks or plutons.
