A permanent collapsing gully,locally called Benggang,formed on slopes with deep granite red soil and is a type of unique gully erosion widely prevalent in southern China.Three different soil configurations(SC),ie,red-...A permanent collapsing gully,locally called Benggang,formed on slopes with deep granite red soil and is a type of unique gully erosion widely prevalent in southern China.Three different soil configurations(SC),ie,red-transition-sandy(SC I,the transition is the soil layer between the red soil and the sandy soil layer),transition-sandy(SC II)or sandy(SC III)are usually present in the soil profile of the Benggang slope.However,little attention has been paid to impacts of SCs on the triggering of Benggang erosion.In this study,we aimed to explore the relationships between soil water content(SWC)and triggering of Benggang erosion under different SC conditions.The soil properties of different soil layers were measured and the SWC at depths of 20,40,60,and 80 cm were monitored at 5-min intervals along a typical Benggang(SC I)during 2016-2018.The SWC of Benggang slopes with different SCs were simulated by VADOSE/W model.Results showed that the red soil layer had a higher water retention capacity and shear strength than the sandy soil layer.Even if the SWC is higher(e.g.,0.42 cm^(3)/cm^(3))at red soil layer or transition layer,the corresponding shear strength is greater than that of sandy soil layer with a lower SWC(e.g.,032 cm^(3)/cm^(3)).Relationships between shear strength and SWC of different soil layers indicate that Benggang erosion is triggered by an increase in the SWC in the deep sandy layer.Results also showed that differences exist in the SWC distribution among the different SCs.The SWC is higher in topsoil than in deeper soil in SC I and SC II,while in SC III,the opposite trend is observed.These results revealed that the presence of the red soil or transition layer can reduce the infiltration of rainwater into the deep sandy layer,thus can reduce the possibility of collapse.Our results show that the SC affects the stability of the headwall,and results provide great significances to guide the mitigation of Benggang erosion.展开更多
This paper presents Symm Sketch—a system for creating symmetric 3D free-form shapes from 2D sketches. The reconstruction task usually separates a 3D symmetric shape into two types of shape components, that is, the se...This paper presents Symm Sketch—a system for creating symmetric 3D free-form shapes from 2D sketches. The reconstruction task usually separates a 3D symmetric shape into two types of shape components, that is, the self-symmetric shape component and the mutual-symmetric shape components. Each type can be created in an intuitive manner. Using a uniform symmetry plane, the user first draws 2D sketch lines for each shape component on a sketching plane. The z-depth information of the hand-drawn input sketches can be calculated using their property of mirror symmetry to generate 3D construction curves. In order to provide more freedom for controlling the local geometric features of the reconstructed free-form shapes(e.g., non-circular crosssections), our modeling system creates each shape component from four construction curves. Using one pair of symmetric curves and one pair of general curves, an improved cross-sectional surface blending scheme is applied to generate a parametric surface for each component. The final symmetric free-form shape is progressively created, and is represented by 3D triangular mesh. Experimental results illustrate that our system can generate complex symmetric free-form shapes effectively and conveniently.展开更多
Typically,relief generation from an input 3D scene is limited to either bas-relief or high-relief modeling.This paper presents a novel unified scheme for synthesizing reliefs guided by the geometric texture richness o...Typically,relief generation from an input 3D scene is limited to either bas-relief or high-relief modeling.This paper presents a novel unified scheme for synthesizing reliefs guided by the geometric texture richness of 3D scenes;it can generate both basand high-reliefs.The type of relief and compression coefficient can be specified according to the user’s artistic needs.We use an energy minimization function to obtain the surface reliefs,which contains a geometry preservation term and an edge constraint term.An edge relief measure determined by geometric texture richness and edge z-depth is utilized to achieve a balance between these two terms.During relief generation,the geometry preservation term keeps local surface detail in the original scenes,while the edge constraint term maintains regions of the original models with rich geometric texture.Elsewhere,in highreliefs,the edge constraint term also preserves depth discontinuities in the higher parts of the original scenes.The energy function can be discretized to obtain a sparse linear system.The reliefs are obtained by solving it by an iterative process.Finally,we apply non-linear compression to the relief to meet the user’s artistic needs.Experimental results show the method’s effectiveness for generating both bas-and high-reliefs for complex 3D scenes in a unified manner.展开更多
基金Financial support for this research was provided by the National Natural Science Foundation of China(No.41571258,42007055 and 41630858).
文摘A permanent collapsing gully,locally called Benggang,formed on slopes with deep granite red soil and is a type of unique gully erosion widely prevalent in southern China.Three different soil configurations(SC),ie,red-transition-sandy(SC I,the transition is the soil layer between the red soil and the sandy soil layer),transition-sandy(SC II)or sandy(SC III)are usually present in the soil profile of the Benggang slope.However,little attention has been paid to impacts of SCs on the triggering of Benggang erosion.In this study,we aimed to explore the relationships between soil water content(SWC)and triggering of Benggang erosion under different SC conditions.The soil properties of different soil layers were measured and the SWC at depths of 20,40,60,and 80 cm were monitored at 5-min intervals along a typical Benggang(SC I)during 2016-2018.The SWC of Benggang slopes with different SCs were simulated by VADOSE/W model.Results showed that the red soil layer had a higher water retention capacity and shear strength than the sandy soil layer.Even if the SWC is higher(e.g.,0.42 cm^(3)/cm^(3))at red soil layer or transition layer,the corresponding shear strength is greater than that of sandy soil layer with a lower SWC(e.g.,032 cm^(3)/cm^(3)).Relationships between shear strength and SWC of different soil layers indicate that Benggang erosion is triggered by an increase in the SWC in the deep sandy layer.Results also showed that differences exist in the SWC distribution among the different SCs.The SWC is higher in topsoil than in deeper soil in SC I and SC II,while in SC III,the opposite trend is observed.These results revealed that the presence of the red soil or transition layer can reduce the infiltration of rainwater into the deep sandy layer,thus can reduce the possibility of collapse.Our results show that the SC affects the stability of the headwall,and results provide great significances to guide the mitigation of Benggang erosion.
基金supported by the National Natural Science Foundation of China under Grant Nos. 61272309 and 61303138
文摘This paper presents Symm Sketch—a system for creating symmetric 3D free-form shapes from 2D sketches. The reconstruction task usually separates a 3D symmetric shape into two types of shape components, that is, the self-symmetric shape component and the mutual-symmetric shape components. Each type can be created in an intuitive manner. Using a uniform symmetry plane, the user first draws 2D sketch lines for each shape component on a sketching plane. The z-depth information of the hand-drawn input sketches can be calculated using their property of mirror symmetry to generate 3D construction curves. In order to provide more freedom for controlling the local geometric features of the reconstructed free-form shapes(e.g., non-circular crosssections), our modeling system creates each shape component from four construction curves. Using one pair of symmetric curves and one pair of general curves, an improved cross-sectional surface blending scheme is applied to generate a parametric surface for each component. The final symmetric free-form shape is progressively created, and is represented by 3D triangular mesh. Experimental results illustrate that our system can generate complex symmetric free-form shapes effectively and conveniently.
基金supported by the National Natural Science Foundation of China under Grant No.61272309
文摘Typically,relief generation from an input 3D scene is limited to either bas-relief or high-relief modeling.This paper presents a novel unified scheme for synthesizing reliefs guided by the geometric texture richness of 3D scenes;it can generate both basand high-reliefs.The type of relief and compression coefficient can be specified according to the user’s artistic needs.We use an energy minimization function to obtain the surface reliefs,which contains a geometry preservation term and an edge constraint term.An edge relief measure determined by geometric texture richness and edge z-depth is utilized to achieve a balance between these two terms.During relief generation,the geometry preservation term keeps local surface detail in the original scenes,while the edge constraint term maintains regions of the original models with rich geometric texture.Elsewhere,in highreliefs,the edge constraint term also preserves depth discontinuities in the higher parts of the original scenes.The energy function can be discretized to obtain a sparse linear system.The reliefs are obtained by solving it by an iterative process.Finally,we apply non-linear compression to the relief to meet the user’s artistic needs.Experimental results show the method’s effectiveness for generating both bas-and high-reliefs for complex 3D scenes in a unified manner.
