We evaluate different Neural Radiance Field(NeRF)techniques for the 3D reconstruction of plants in varied environments,from indoor settings to outdoor fields.Traditional methods usually fail to capture the complex geo...We evaluate different Neural Radiance Field(NeRF)techniques for the 3D reconstruction of plants in varied environments,from indoor settings to outdoor fields.Traditional methods usually fail to capture the complex geometric details of plants,which is crucial for phenotyping and breeding studies.We evaluate the reconstruction fidelity of NeRFs in 3 scenarios with increasing complexity and compare the results with the point cloud obtained using light detection and ranging as ground truth.In the most realistic field scenario,the NeRF models achieve a 74.6%F1 score after 30 min of training on the graphics processing unit,highlighting the efficacy of NeRFs for 3D reconstruction in challenging environments.Additionally,we propose an early stopping technique for NeRF training that almost halves the training time while achieving only a reduction of 7.4%in the average F1 score.This optimization process substantially enhances the speed and efficiency of 3D reconstruction using NeRFs.Our findings demonstrate the potential of NeRFs in detailed and realistic 3D plant reconstruction and suggest practical approaches for enhancing the speed and efficiency of NeRFs in the 3D reconstruction process.展开更多
Structure-from-Motion(SfM)techniques have been widely used for 3D geometry reconstruction from multi-view images.Nevertheless,the efficiency and quality of the reconstructed geometry depends on multiple factors,i.e.,t...Structure-from-Motion(SfM)techniques have been widely used for 3D geometry reconstruction from multi-view images.Nevertheless,the efficiency and quality of the reconstructed geometry depends on multiple factors,i.e.,the base-height ratio,intersection angle,overlap,and ground control points,etc.,which are rarely quantified in real-world applications.To answer this question,in this paper,we take a data-driven approach by analyzing hundreds of terrestrial stereo image configurations through a typical SfM algorithm.Two main meta-parameters with respect to base-height ratio and intersection angle are analyzed.Following the results,we propose a Skeletal Camera Network(SCN)and embed it into the SfM to lead to a novel SfM scheme called SCN-SfM,which limits tie-point matching to the remaining connected image pairs in SCN.The proposed method was applied in three terrestrial datasets.Experimental results have demonstrated the effectiveness of the proposed SCN-SfM to achieve 3D geometry with higher accuracy and fast time efficiency compared to the typical SfM method,whereas the completeness of the geometry is comparable.展开更多
One can compute the final deformation of a known geometry under specific boundary conditions using the constitutive laws of mechanics that describe their stress strain behavior.In such cases the initial geometry is kn...One can compute the final deformation of a known geometry under specific boundary conditions using the constitutive laws of mechanics that describe their stress strain behavior.In such cases the initial geometry is known,and all operators mapping the deformation are defined on the reference domain.However,there are situations in which the final configuration of a deformation might be known but not the initial.The inverse formulation allows one to determine the initial geometry of a domain,given its final deformation state,the material behavior law and a set of boundary conditions.In the present work we propose a method to reconstruct the mesoscale geometry of a textile based on its mechanical response during compaction.To do so,stress boundary conditions are acquired by means of a pressuresensitive film.By adopting an appropriate material law,the thickness and width information of the yarns are deduced from the pressure field experienced by the compacted textile.Unlike 3 D scanning techniques such as-CT,the proposed method can be applied on any domain size,allowing long-range variability to be captured.To the best of the authors’knowledge,there are no previous works that use a pressure-sensitive film on a large domain to capture the input data for a shape reconstruction.This example application serves as a demonstration of a methodology which could be applied to other classes of materials.展开更多
In this paper,we propose a method of fixing the leading behaviors of three dimensional geometries from the dual CFT_(2)entanglement entropies.We employ only the holographic principle and do not use any assumption abou...In this paper,we propose a method of fixing the leading behaviors of three dimensional geometries from the dual CFT_(2)entanglement entropies.We employ only the holographic principle and do not use any assumption about the AdS/CFT correspondence and bulk geometry.Our strategy involves using both UV and IR-like CFT_(2)entanglement entropies to fix the bulk geodesics.With a simple trick,the metric can be extracted from the geodesics.As examples,we fix the leading behaviors of the pure AdS3 metric from the entanglement entropies of free CFT_(2)and,more importantly,the BTZ black hole from the entanglement entropies of finite temperature CFT_(2).Consequently,CFT_(2)with finite size or topological defects can be determined through simple transformations.Following the same steps,in principle,the leading behaviors of all three dimensional(topologically distinct)holographic classical geometries from the dual CFT_(2)entanglement entropies can be fixed.展开更多
Virtual globes are technologies for visual navigation through a threedimensional,multi-resolution model of the entire planet.Data representations used in virtual globes,however,lack geometric flexibility at high-resol...Virtual globes are technologies for visual navigation through a threedimensional,multi-resolution model of the entire planet.Data representations used in virtual globes,however,lack geometric flexibility at high-resolution levels of the planet-wide terrain surface.This is a problem especially if boundaries between individual geospatial features and the terrain are important.A novel integration of individual polygonal boundaries with a specific multi-resolution representation of the planet-wide terrain is developed in this article.In the preparation stage,the integration relies on an original simplification algorithm applied to the polygonal boundaries between geospatial features and the terrain.Its output is a multiple level-of-detail(LOD)geometry,which can be combined with a known multi-LOD representation of the terrain that uses run-time triangulation.This data representation is suitable for storage in existing database systems,avoids any data redundancy across LODs,and is even independent of the subdivision schema that partitions the planet’s surface for the sake of dealing with LODs.At runtime,a novel reconstruction algorithm stitches geometric parts from different LODs together in a manner that augments the multi-LOD representation of the terrain.Within a certain proximity range from a given position,the method reconstructs a scene that preserves topological relations between the boundaries of geospatial features with the terrain.The method also guarantees that certain nearest proximity to the given position consists of the best geometries that correspond to the original datasets.Such properties of the method close up the gap between a mere exploratory visualization of static,pre-generated models and the models supporting geospatial analysis,which is deemed crucial for applications in Geographic Information Systems,Building Information Modelling and other software industries.A prototype implementation and experiment results that prove this method are also presented.展开更多
Newtonian, Quemada and Casson blood viscosity models are implemented in order to simulate the rheological behavior of blood under pulsating flow conditions in a patient specific iliac bifurcation. The influence of the...Newtonian, Quemada and Casson blood viscosity models are implemented in order to simulate the rheological behavior of blood under pulsating flow conditions in a patient specific iliac bifurcation. The influence of the applied blood constitutive equations is monitored via the wall shear stress （WSS） distribution, magnitude and oscillations, non-Newtonian importance factors, and viscosity values according to the shear rate. The distribution of WSS on the vascular wall follows a pattern which is independent of the theological model chosen. On the other hand, the WSS magnitude and oscillations are directly related to the blood constitutive equations applied and the shear rate. It is concluded that the Newtonian approximation is satisfactory only in high shear and flow rates. Moreover, the Newtonian model seems to overestimate the possibility for the formation of atherosclerotic lesions or aneurysms at sites of the vascular wall where the WSS are oscillating.展开更多
基金supported in part by the Plant Science Institute at IowaState University,the National Science Foundation under grant number OAC:1750865the National Institute of Food and Agriculture(USDA-NIFA)as part of the AI Institute for Resilient Agriculture(AIIRA),grant number 2021-67021-35329.
文摘We evaluate different Neural Radiance Field(NeRF)techniques for the 3D reconstruction of plants in varied environments,from indoor settings to outdoor fields.Traditional methods usually fail to capture the complex geometric details of plants,which is crucial for phenotyping and breeding studies.We evaluate the reconstruction fidelity of NeRFs in 3 scenarios with increasing complexity and compare the results with the point cloud obtained using light detection and ranging as ground truth.In the most realistic field scenario,the NeRF models achieve a 74.6%F1 score after 30 min of training on the graphics processing unit,highlighting the efficacy of NeRFs for 3D reconstruction in challenging environments.Additionally,we propose an early stopping technique for NeRF training that almost halves the training time while achieving only a reduction of 7.4%in the average F1 score.This optimization process substantially enhances the speed and efficiency of 3D reconstruction using NeRFs.Our findings demonstrate the potential of NeRFs in detailed and realistic 3D plant reconstruction and suggest practical approaches for enhancing the speed and efficiency of NeRFs in the 3D reconstruction process.
基金National Natural Science Foundation of China(No.41701534)Open Fund of State Key Laboratory of Coal Resources and Safe Mining(No.SKLCRSM19KFA01)+1 种基金Ecological and Smart Mine Joint Foundation of Hebei Province(No.E2020402086)State Key Laboratory ofGeohazard Prevention and Geoenvironment Protection(No.SKLGP2019K015)
文摘Structure-from-Motion(SfM)techniques have been widely used for 3D geometry reconstruction from multi-view images.Nevertheless,the efficiency and quality of the reconstructed geometry depends on multiple factors,i.e.,the base-height ratio,intersection angle,overlap,and ground control points,etc.,which are rarely quantified in real-world applications.To answer this question,in this paper,we take a data-driven approach by analyzing hundreds of terrestrial stereo image configurations through a typical SfM algorithm.Two main meta-parameters with respect to base-height ratio and intersection angle are analyzed.Following the results,we propose a Skeletal Camera Network(SCN)and embed it into the SfM to lead to a novel SfM scheme called SCN-SfM,which limits tie-point matching to the remaining connected image pairs in SCN.The proposed method was applied in three terrestrial datasets.Experimental results have demonstrated the effectiveness of the proposed SCN-SfM to achieve 3D geometry with higher accuracy and fast time efficiency compared to the typical SfM method,whereas the completeness of the geometry is comparable.
基金partially funded by Conseil Regional Pays de la Loire(grant number TEU29)。
文摘One can compute the final deformation of a known geometry under specific boundary conditions using the constitutive laws of mechanics that describe their stress strain behavior.In such cases the initial geometry is known,and all operators mapping the deformation are defined on the reference domain.However,there are situations in which the final configuration of a deformation might be known but not the initial.The inverse formulation allows one to determine the initial geometry of a domain,given its final deformation state,the material behavior law and a set of boundary conditions.In the present work we propose a method to reconstruct the mesoscale geometry of a textile based on its mechanical response during compaction.To do so,stress boundary conditions are acquired by means of a pressuresensitive film.By adopting an appropriate material law,the thickness and width information of the yarns are deduced from the pressure field experienced by the compacted textile.Unlike 3 D scanning techniques such as-CT,the proposed method can be applied on any domain size,allowing long-range variability to be captured.To the best of the authors’knowledge,there are no previous works that use a pressure-sensitive film on a large domain to capture the input data for a shape reconstruction.This example application serves as a demonstration of a methodology which could be applied to other classes of materials.
基金Supported in part by the the National Nature Science Foundation of China(12105191,12275183,12275184)。
文摘In this paper,we propose a method of fixing the leading behaviors of three dimensional geometries from the dual CFT_(2)entanglement entropies.We employ only the holographic principle and do not use any assumption about the AdS/CFT correspondence and bulk geometry.Our strategy involves using both UV and IR-like CFT_(2)entanglement entropies to fix the bulk geodesics.With a simple trick,the metric can be extracted from the geodesics.As examples,we fix the leading behaviors of the pure AdS3 metric from the entanglement entropies of free CFT_(2)and,more importantly,the BTZ black hole from the entanglement entropies of finite temperature CFT_(2).Consequently,CFT_(2)with finite size or topological defects can be determined through simple transformations.Following the same steps,in principle,the leading behaviors of all three dimensional(topologically distinct)holographic classical geometries from the dual CFT_(2)entanglement entropies can be fixed.
基金This work has been supported by Charles University Research Centre program UNCE/HUM/018.
文摘Virtual globes are technologies for visual navigation through a threedimensional,multi-resolution model of the entire planet.Data representations used in virtual globes,however,lack geometric flexibility at high-resolution levels of the planet-wide terrain surface.This is a problem especially if boundaries between individual geospatial features and the terrain are important.A novel integration of individual polygonal boundaries with a specific multi-resolution representation of the planet-wide terrain is developed in this article.In the preparation stage,the integration relies on an original simplification algorithm applied to the polygonal boundaries between geospatial features and the terrain.Its output is a multiple level-of-detail(LOD)geometry,which can be combined with a known multi-LOD representation of the terrain that uses run-time triangulation.This data representation is suitable for storage in existing database systems,avoids any data redundancy across LODs,and is even independent of the subdivision schema that partitions the planet’s surface for the sake of dealing with LODs.At runtime,a novel reconstruction algorithm stitches geometric parts from different LODs together in a manner that augments the multi-LOD representation of the terrain.Within a certain proximity range from a given position,the method reconstructs a scene that preserves topological relations between the boundaries of geospatial features with the terrain.The method also guarantees that certain nearest proximity to the given position consists of the best geometries that correspond to the original datasets.Such properties of the method close up the gap between a mere exploratory visualization of static,pre-generated models and the models supporting geospatial analysis,which is deemed crucial for applications in Geographic Information Systems,Building Information Modelling and other software industries.A prototype implementation and experiment results that prove this method are also presented.
基金supported by the National Strategic Reference Framework(NSRF)2007-2013 project DEKA:“Integrated prognostic system for risk assessment in stent implantations for Abdominal Aortic Aneurysm repair”(Grant No.09SYN-12-1153)
文摘Newtonian, Quemada and Casson blood viscosity models are implemented in order to simulate the rheological behavior of blood under pulsating flow conditions in a patient specific iliac bifurcation. The influence of the applied blood constitutive equations is monitored via the wall shear stress （WSS） distribution, magnitude and oscillations, non-Newtonian importance factors, and viscosity values according to the shear rate. The distribution of WSS on the vascular wall follows a pattern which is independent of the theological model chosen. On the other hand, the WSS magnitude and oscillations are directly related to the blood constitutive equations applied and the shear rate. It is concluded that the Newtonian approximation is satisfactory only in high shear and flow rates. Moreover, the Newtonian model seems to overestimate the possibility for the formation of atherosclerotic lesions or aneurysms at sites of the vascular wall where the WSS are oscillating.
