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A 3D geological model and cutting algorithm based on a vertically projected triangulated network

COMPUTERS & GEOSCIENCES 2020年 143卷 104562-104562页

作者： Zhou, Cuiying Du, Zichun Ouyang, Jinwu Zhang, Zhilong Liu, Zhen Sun Yat Sen Univ Guangzhou Peoples R China Guangdong Engn Res Ctr Major Infrastruct Safety Guangzhou Peoples R China

Displaying 3D geological models and performing corresponding analyses in web browsers are trends in "smart city" development, but these tasks are often limited by the web browser and network transmission;therefore, large quantities of data cannot be quickly displayed or analysed, thereby constraining 3D geological models implemented in web browsers. The data redundancy and computational complexity of 3D geological models must be urgently optimized. Because of the data structure, it is difficult to further optimize the data redundancy and computational complexity of the current commonly used triangular prism (TP) model. If the model is sufficiently large, it can be difficult to display and analyse information in a web browser. Therefore, a new data structure and algorithm are necessary to optimize the data and number of calculations in 3D geological models. Thus, this paper uses a two-dimensional projection to simplify the data and proposes a new data structure for a 3D geological model based on a vertically projected triangulated network (VPTN) to describe the TP model. Based on the vertical sides of a TP, the horizontal coordinates and topology of the 3D model can be recorded by a 2D vertically projected triangulated network. According to the new data structure, this paper proposes a corresponding cutting algorithm that takes advantage of a VPTN to increase the computational speed. The VPTN model and TP model of a city in eastern China are built. The comparison of the modelling and cutting results of the two models is carried out, and the results show that the VPTN model can completely record the spatial coordinate information and topological information of the 3D geological model, reduce the memory space occupied by the model and decrease the number of calculations. The research results meet the needs of rapidly displaying 3D geological models and performing related analyses with a large data volume in web browsers. Moreover, these findings provide a reference for

关键词： Vertically projected triangulated network 3D geological model cutting algorithm Topological relation Redundancy optimization

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An All-in-One Geometric algorithm for cutting, Tearing, and Drilling Deformable Models

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ADVANCES IN APPLIED CLIFFORD ALGEBRAS 2021年第3期31卷 1-24页

作者： Kamarianakis, Manos Papagiannakis, George Univ Crete Iraklion Greece ORamaVR Co Geneva Switzerland

Conformal geometric algebra (CGA) is a framework that allows the representation of objects, such as points, planes and spheres, and deformations, such as translations, rotations and dilations as uniform vectors, called multivectors. In this work, we demonstrate the merits of multivector usage with a novel, integrated rigged character simulation framework based on CGA. In such a framework, and for the first time, one may perform real-time cuts and tears as well as drill holes on a rigged 3D model. These operations can be performed before and/or after model animation, while maintaining deformation topology. Moreover, our framework permits generation of intermediate keyframes on-the-fly based on user input, apart from the frames provided in the model data. We are motivated to use CGA as it is the lowest-dimension extension of dual-quaternion algebra that amends the shortcomings of the majority of existing animation and deformation techniques. Specifically, we no longer need to maintain objects of multiple algebras and constantly transmute between them, such as matrices, quaternions and dual-quaternions, and we can effortlessly apply dilations. Using such an all-in-one geometric framework allows for better maintenance and optimization and enables easier interpolation and application of all native deformations. Furthermore, we present these three novel algorithms in a single CGA representation which enables cutting, tearing and drilling of the input rigged model, where the output model can be further re-deformed in interactive frame rates. These close to real-time cut,tear and drill algorithms can enable a new suite of applications, especially under the scope of a medical VR simulation.

关键词： Conformal geometric algebra (CGA) Skinning Interpolation cutting algorithm Tearing algorithm Drilling algorithm Keyframe generation

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Deform, Cut and Tear a Skinned Model Using Conformal Geometric Algebra 37th

Deform, Cut and Tear a Skinned Model Using Conformal Geometr...

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37th Computer Graphics International (CGI) Conference

作者： Kamarianakis, Manos Papagiannakis, George Univ Crete Iraklion Greece ORamaVR Iraklion Greece

ISBN: (纸本)9783030618636;9783030618643

In this work, we present a novel, integrated rigged character simulation framework in Conformal Geometric Algebra (CGA) that supports, for the first time, real-time cuts and tears, before and/or after the animation, while maintaining deformation topology. The purpose of using CGA is to lift several restrictions posed by current state-of-the-art character animation & deformation methods. Previous implementations originally required weighted matrices to perform deformations, whereas, in the current state-of-the-art, dual-quaternions handle both rotations and translations, but cannot handle dilations. CGA is a suitable extension of dual-quaternion algebra that amends these two major previous shortcomings: the need to constantly transmute between matrices and dual-quaternions as well as the inability to properly dilate a model during animation. Our CGA algorithm also provides easy interpolation and application of all deformations in each intermediate steps, all within the same geometric framework. Furthermore we also present two novel algorithms that enable cutting and tearing of the input rigged, animated model, while the output model can be further re-deformed. These interactive, real-time cut and tear operations can enable a new suite of applications, especially under the scope of a medical surgical simulation.

关键词： Conformal Geometric Algebra (CGA) Skinning Interpolation cutting algorithm Tearing algorithm Keyframe generation

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Research on Prepreg Tape cutting Platform with Two Cutters

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第3期36卷 442-448页

作者： WEN Liwei HUANG Xiaochuan QIN Lihua WANG Xianfeng LI Yong College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics

The concept of cutting platform is proposed and realized based on the latest two step automated tape laying (Two step ATL)technology,which separates prepreg cutting process from tape laying to improve productivity for large parts with small *** step ATL is more efficient than conventional layup because ply patches are pre cut in a separate *** concept of the prepreg tape cutting experimental platform with two cutters is ***,based on the automatic tape laying trajectory planning software,a two cutter cutting algorithm is *** experiments are reported to validate both the concept of cutting platform and cutting algorithm.

关键词： two-step automated tape laying(Two-step ATL) cutting platform with two cutters cutting algorithm cutter distribution

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Implementation Method of cutting Simulation Based on Transient Display and Delay Adjustment Strategy

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WIRELESS PERSONAL COMMUNICATIONS 2018年第1期103卷 25-40页

作者： Wang, Monan Mao, Zhiyong Harbin Univ Sci & Technol Mech & Power Engn Coll 52 Xuefu Rd Harbin 150080 Heilongjiang Peoples R China

In the light of the problems that exist in the current cutting algorithms: first, the number of tetrahedron elements increases as the cutting goes on, which leads to the decrease of the algorithm efficiency. Second, the topology structure is constantly updated during the cutting process, which leads to the stutter phenomenon in cutting display. In this paper, a cutting simulation implementation method based on transient display and delay adjustment strategy is proposed. Firstly, the feature points in the original path are screened by the feature criterion function, and the feature path is established. Then, by using the concept of minimum sum of square defined in this paper, the optimal path of the separation is found with the help of feature path points, and the pseudo effect of cutting is directly displayed by designing the transient display module. The delay adjustment is carried out in the cutting gap, and the topology separation in the delay adjustment is implemented by the node offset spread algorithm and the duplicate removal process with timeliness. Finally, the advantages and feasibility of the cutting algorithm proposed in this paper are verified by practical tests. The test results show that the transient display algorithm proposed in this paper takes about 20ms. With the number of triangular patches increasing, the growth rate of transient display time remains low. The cutting simulation is implemented by using transient display and delay adjustment strategy, which greatly improves the simulation efficiency.

关键词： cutting algorithm Program design Transient display Delay adjustment Path separation

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Method for generating pore networks in porous particles of arbitrary shape, and its application to catalytic hydrogenation of benzene

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CHEMICAL ENGINEERING JOURNAL 2017年 329卷 56-65页

作者： Ye, Guanghua Sun, Yuanyuan Zhou, Xinggui Zhu, Kake Zhou, Jinghong Coppens, Marc-Olivier East China Univ Sci & Technol State Key Lab Chem Engn Shanghai 200237 Peoples R China UCL Dept Chem Engn London WC1E 7JE England

A method is established to generate pore networks within domains of arbitrary shape, as long as the domain can be mathematically described by a set of inequalities. In this method, a stochastic network algorithm is adopted to construct pore network skeletons, which are then cut into the desired shapes using a new pore network cutting algorithm. The latter can be embedded into other methods to transplant its 'pore network cutting' function. Using this method, pore networks with four archetypical two-dimensional shapes (namely, cross-sections of one-holed rings, trilobes, four-holed rings, and wheels) and four three-dimensional shapes (namely, spheres, cylinders, trilobes, and hollow cylinders) are constructed as examples. Then, some of these pore networks are applied to simulate diffusion and reaction in Pd/c-alumina catalyst particles for hydrogenation of benzene to cyclohexane. It is shown that the randomness of the pore network and the external particle shape significantly affect the performance of catalysts, because of their impact on effective diffusivity and diffusion length, respectively, indicating that this structural information must be accounted for to achieve a model with high accuracy. The versatile method proposed in this article is ideal to study the effect of particle shape and pore network structure on the performance of porous materials for catalysis and other applications. (C) 2017 Elsevier B.V. All rights reserved.

关键词： Porous materials Pore network Particle shape cutting algorithm Hydrogenation of benzene Catalysis

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Graphic and haptic simulation system for virtual laparoscopic rectum surgery

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INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY 2011年第3期7卷 304-317页

作者： Pan, Jun J. Chang, Jian Yang, Xiaosong Zhang, Jian J. Qureshi, Tahseen Howell, Robert Hickish, Tamas Bournemouth Univ Media Sch Natl Ctr Comp Animat Poole BH12 5BB Dorset England Poole Hosp Poole Dorset England Christchurch Hosp Bournemouth Dorset England Royal Bournemouth Hosp Bournemouth Dorset England

Background Medical simulators with vision and haptic feedback techniques offer a cost-effective and efficient alternative to the traditional medical trainings. They have been used to train doctors in many specialties of medicine, allowing tasks to be practised in a safe and repetitive manner. This paper describes a virtual-reality (VR) system which will help to influence surgeons' learning curves in the technically challenging field of laparoscopic surgery of the rectum. Methods Data from MRI of the rectum and real operation videos are used to construct the virtual models. A haptic force filter based on radial basis functions is designed to offer realistic and smooth force feedback. To handle collision detection efficiently, a hybrid model is presented to compute the deformation of intestines. Finally, a real-time cutting technique based on mesh is employed to represent the incision operation. Results Despite numerous research efforts, fast and realistic solutions of soft tissues with large deformation, such as intestines, prove extremely challenging. This paper introduces our latest contribution to this endeavour. With this system, the user can haptically operate with the virtual rectum and simultaneously watch the soft tissue deformation. Conclusions Our system has been tested by colorectal surgeons who believe that the simulated tactile and visual feedbacks are realistic. It could replace the traditional training process and effectively transfer surgical skills to novices. Copyright (C) 2011 John Wiley & Sons, Ltd.

关键词： cutting algorithm haptic force filter laparoscopic rectum surgery virtual reality

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Preliminary Study on Virtual cutting Technology Based on Tactile Feedback

Preliminary Study on Virtual Cutting Technology Based on Tac...

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2011 IEEE 12th International Conference on Computer-Aided Industrial Design & Conceptual Design

作者： ZHOU Yan School of Mechatronic Engineering Harbin institute of technology Harbin,China HU Dengming School of Mechatronic Engineering Harbin institute of technology Harbin,China TANG Ruoyue School of Mechatronic Engineering Harbin institute of technology Harbin,China

This paper studies the virtual cutting technology, based on the study of existing virtual cutting model and related cutting algorithm,using PHANTOM Omni tactile feedback device.A research program of virtual cutting technology is proposed on the base of tactile feedback, providing a theoretical basis for the study of making virtual model in the process of product design.

关键词： tactile feedback virtual cutting models cutting algorithm

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An Optimal Mapping algorithm Based on Balanced Load cutting for DVE Systems

An Optimal Mapping Algorithm Based on Balanced Load Cutting ...

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3rd International Symposium on Intelligent Information Technology Application

作者： Zhang, Wei Xi, Min Zhou, Hangjun Peng, Yuxing Li, Sikun Natl Univ Def Technol Sch Comp Sci Natl Lab Parallel & Distributed Proc Changsha 410073 Hunan Peoples R China Xi An Jiao Tong Univ Dept Comp Sci Xian 710049 Peoples R China

ISBN: (纸本)9780769538594

In Distributed Virtual Environment (DVE) systems, a distributed server infrastructure is often used to reduce the latency between servers and clients. Under this infrastructure, mapping clients to proper servers is one of the key issues for improving the interactivity and overall performance. Most traditional methods of mapping the clients to servers only consider the load balancing problem. However, there are two other important aspects that should be involved: the physical world integrity and the virtual world integrity. In this work, we propose a novel mapping algorithm which takes care of all three aspects at the same time. The algorithm converts the mapping problem into cutting stage and matching stage to get optimal result with polynomial complexity. The experimental results show that our algorithm improves the overall performance of DVE systems significantly.

关键词： DVE systems mapping algorithm cutting algorithm

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Graphic and haptic modelling of the oesophagus for VR-based medical simulation

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INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY 2009年第3期5卷 257-266页

作者： Choi, Changmok Kim, Jungsik Han, Hyonyung Ahn, Bummo Kim, Jung Korea Adv Inst Sci & Technol Dept Mech Engn Room 5201Mech Engn Bldg Taejon 305701 South Korea

Background Medical simulators with vision and haptic feedback have been applied to many medical procedures in recent years, due to their safe and repetitive nature for training. Among the many technical components of the simulators, realistic and interactive organ modelling stands out as a key issue for judging the fidelity of the simulation. This paper describes the modelling of an oesophagus for a real-time laparoscopic surgical simulator. Methods For realistic simulation, organ deformation and tissue cutting in the oesophagus are implemented with geometric organ models segmented from the Visible Human Dataset. The tissue mechanical parameters were obtained from in vivo animal experiments and integrated with graphic and haptic devices into the laparoscopic surgical simulation system inside an abdominal mannequin. Results This platform can be used to demonstrate deformation and incision of the oesophagus by surgical instruments, where the user can haptically interact with the virtual soft tissues and simultaneously see the corresponding organ deformation on the visual display. Conclusions Current laparoscopic surgical training has been transformed from the traditional apprenticeship model to simulation-based methods. The outcome of the model could replace conventional training systems and could be useful in effectively transferring surgical skills to novice surgeons. Copyright (C) 2009 John Wiley & Sons, Ltd.

关键词： medical simulation physically-based organ model cutting algorithm

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