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建筑模拟(英文) 2023年第8期16卷 1481-1498页

作者： Jeetika Malik Handi Chandra Putra Kaiyu Sun Tianzhen Hong Building Technology and Urban System Division Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA

Occupant behavior(OB)is one of the significant sources of uncertainty in building performance simulation.While OB modeling has received increased attention in the past decade,research on the degree of granularity or level of detail(LoD)required for representing occupants is still in the nascent stages.This paper analyzes the modeling and applicability of three LoDs to represent occupants in building performance assessment.A medium-sized prototype office building located in Chicago,Illinois is used as the simulation case study.Ten occupant-centric attributes are adopted to develop the LoDs for OB representation.We first demonstrate the different modeling approaches required for simulating the three fidelity levels.Later,we illustrate the suitability of the developed LoDs in supporting six building performance use cases across different lifecycle stages.This study intends to provide guidance for the building simulation community on appropriate OB representation to support various use cases.

关键词： occupant behavior agent-based modeling building performance simulation level of detail fit-for-purpose office buildings

Volumetric Virtual Environments

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Journal of Computer Science & Technology 2000年第1期15卷 37-46页

作者： HE Taosong(Software Production Research Department, Bell LaboratoriesLucent Technologies, Naperville, IL 60566, USA)E-mail: taosong@*** Software Production Research Department Bell Laboratories Lucent Technologies Naperville USA

Driven by fast development of both virtual reality and volume visualization, we discuss some critical techniques towards building a volumetric VRsystem, specifically the modeling, rendering, and manipulations of a volumetric scene.Techniques such as voxel-based object simplification, accelerated volume rendering,fast stereo volume rendering, and volumetric 'collision detection' are introduced andimproved, with the idea of demonstrating the possibilities and potential benefits ofincorporating volumetric models into VR systems.

关键词： volume visualization volume rendering virtual reality volumegraphics object simplification level of detail wavelets theory volumetric collisiondetection

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A New Mesh Simplification Algorithm Based on Triangle Collapses

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Journal of Computer Science & Technology 2001年第1期16卷 57-63页

作者：潘志庚周昆石教英 State Key Laboratory of CAD & CG Zhejiang University Hangzhou 310027 P.R. ChinaDepartment of Computing Hong Kong Polytechnic University Hong Kong P.R. China State Key Laboratory of CAD & CG Zhejiang University Hangzhou 310027 P.R. China

In this paper a new mesh simplification algorithm based on triangle collapses is presented. The algorithm can provide efficient error management and simplify the original mesh greatly. Progressive meshes may be constructed with triangle collapsing operation. To make continuous transition between level of detail (LOD) models possible, a method for interpolating is also presented. Examples illustrate the efficiency of the algorithm.

关键词： mesh simplification triangle mesh level of detail progressive mesh

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Modeling in Multi-Resolution and Its Applications

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Journal of Computer Science & Technology 2006年第2期21卷 272-278页

作者： Sungchan Kim Kunwoo Lee Taesik Hong Moonki Jung School of Mechanical and Aerospace Engineering Seoul National University San 56-1 Sillim-Dong Gwanak-Gu Seoul 151-752 Korea

It is becoming common for many designers to work together on very complex assemblies in a collaborative environment. To work efficiently in this environment, the capabilities to simplify the portions of an assembly and to reset it to the original resolution should be added to the current CAD systems. Thus operators realizing multi-resolution on B-rep were proposed in previous work. This paper illustrates a prototype multi-resolution system to integrate the proposed operators and its applications. The multi-resolution system can be used in similarity comparisons to reduce the calculation load and to get the full comparison result in the overall shape. Then the features recognized with this system can be used in more detailed comparisons. This system also can be used conceptually to solve security problems in collaborative design.

关键词： collaborative design level of detail multi-resolution similarity comparison

Three-dimensional trees for virtual globes

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International Journal of Digital Earth 2014年第10期7卷 789-810页

作者： Cristina Rebollo Inmaculada Remolar Jesus Gumbau Miguel Chover Institute of New Imaging Technologies Universitat Jaume ICastellonSpain

One of the problems in virtual globes technologies is the real-time representation of vegetal species.In forest or garden representations,the low detailed plants produce a lack of realism.Efficient techniques are required to achieve accurate interactive visualisation due to the great number of polygons the vegetal species have.This article presents a multi-resolution model based on a geometric representation of vegetal species that allows the application to perform the progressive transmission of the model,that is,the transmission of a simple representation followed by successive refinements of it.It has a hardware-oriented design in order to obtain interactive frame rates.The geometric data of the objects are stored in the graphics processing unit and,moreover,the change from one approximation to another is obtained by performing mathematical calcula-tions in this graphics hardware.The multi-resolution model presented here enables instancing:as many vegetal species as desired can be rendered with different levels of detail,while all of them are accessing the same geometric data.This model has been used to build a real-time representation of a not imaginary scenario.

关键词： virtual globes real-time rendering vegetal species level of detail graphics hardware progressive transmission

A multi-source data fusion modeling method for debris flow prevention engineering

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Journal of Mountain Science 2021年第4期18卷 1049-1061页

作者： XU Qing-yang YE Jian LYU Yi-jie Faculty of Geoscience and Environmental Engineering Southwest Jiao tong UniversityChengdu 611756China

The Digital Elevation Model(DEM)data of debris flow prevention engineering are the boundary of a debris flow prevention simulation,which provides accurate and reliable DEM data and is a key consideration in debris flow prevention simulations.Thus,this paper proposes a multi-source data fusion method.First,we constructed 3D models of debris flow prevention using virtual reality technology according to the relevant specifications.The 3D spatial data generated by 3D modeling were converted into DEM data for debris flow prevention engineering.Then,the accuracy and applicability of the DEM data were verified by the error analysis testing and fusion testing of the debris flow prevention simulation.Finally,we propose the levels of detail algorithm based on the quadtree structure to realize the visualization of a large-scale disaster prevention scene.The test results reveal that the data fusion method controlled the error rate of the DEM data of the debris flow prevention engineering within an allowable range and generated 3D volume data(obj format)to compensate for the deficiency of the DEM data whereby the 3D internal entity space is not expressed.Additionally,the levels of detailed method can dispatch the data of a large-scale debris flow hazard scene in real time to ensure a realistic 3D visualization.In summary,the proposed methods can be applied to the planning of debris flow prevention engineering and to the simulation of the debris flow prevention process.

关键词： Debris flow prevention level of detail Debris flow simulation Multi platform fusion Multi source data fusion

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An interactive rendering system using hierarchical data structure for earth-scale clouds

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Science China(Information Sciences) 2010年第5期53卷 920-931页

作者： DOBASHI Yoshinori YAMAMOTO Tsuyoshi NISHITA Tomoyuki Graduate School of Information Science and Technology Hokkaido University Graduate School of Frontier Science The University of Tokyo

This paper presents an interactive system for realistic visualization of earth-scale clouds. Realistic images can be generated at interactive frame rates while the viewpoint and the sunlight directions can be changed interactively. The realistic display of earth-scale clouds requires us to render large volume data representing the density distribution of the clouds. However, this is generally time-consuming and it is difficult to achieve the interactive performance, especially when the sunlight direction can be changed. To address this, our system precomputes the integrated intensities and opacities of clouds for various viewing and sunlight directions. This idea is combined with a novel hierarchical data structure for further acceleration. The photorealism of the final image is improved by taking into account the atmospheric effects and shadows of clouds on the earth. We demonstrate the usefulness of our system by an application to a space flight simulation.

关键词： computer graphics efficient rendering large-scale clouds level of detail light scattering

Research on Block Storage and Analysis Model for Belt and Road Initiative Ecological Carrying Capacity Evaluation System

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国际计算机前沿大会会议论文集 2020年第2期 354-368页

作者： Lihu Pan Yunkai Li Yu Dong Huimin Yan School of Computer Science and Technology Taiyuan University of Science and TechnologyTaiyuan 030024China Institute of Geographic Science and Natural Resource Research Chinese Academy of ScienceBeijing 100101China Jilin Provincial Department of Natural Resources Changchun 130000China

Assessment and analysis of ecological carrying capacity are significant issues in regional sustainable development.Large-scale ecological carrying capacity research consume a lot of time and labor costs.In this paper,considering redundant storage,on-demand computing,and multi-scale representation,a block storage and analysis model(BSAM)is proposed to make computation faster.Taking“The Belt and Road Initiative”as an example,the ecological carrying capacity evaluation system(ECCES)was developed.The results show that the problems of low calculation efficiency and high time cost were effectively solved with improved data storage,analysis,and expression approaches used by the ECCES.And the calculation speed is improved with the BSAM.Moreover,in the BSAM,the complexity of the original data is under a more significant impact on computing speed.In contrast,the complexity of an algorithm has a smaller influence on computing speed.Furthermore,the early warning push function and automated report function can generate the ecological carrying capacity states or changes automatically,which can improve the real-time,usability,and convenience of the ecological carrying capacity assessment.

关键词： Sustainable development Multi-scale expression Tile storage Ecological carrying state level of detail

Real-time rendering algorithm based on a hybrid rendering scheme

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Progress in Natural Science:Materials International 2000年第2期 63-68+83页

作者：郑文庭鲍虎军彭群生孙汉秋 310027 China Hangzhou State Key Laboratory of CAD&CG The Chinese University of HongKong Zhejiang University

A real-time rendering algorithm based on a hybrid rendering scheme is presented. The key frames of the virtual scene are generated with a geometry-based approach, then a non-linear transformation to all visible points of each frame near the current viewpoint is performed to reveal their coplanar characteristics and a hierarchical polygon approximation of the local scene is set up. Any intermediate image between the two key frames could be obtained by re-projecting these polygons onto the view plane related to the current viewpoint. The gaps that might appear on the intermediate image are filled through bi-directional backward image warping. Experimental results show that our approach is insensitive to the complexity of the scene and has a satisfactory performance.

关键词： virtual reality image-based rendering level of detail texture mapping.

Hierarchical surface fragments

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Progress in Natural Science:Materials International 2002年第9期 63-71页

作者： HUA Wei , BAO Hujun and PENG Qunsheng(State Key Laboratory of CAD & CG, Zhejiang University, Hangzhou 310027, China) State Key Laboratory of CAD & CG Zhejiang University Hangzhou 310027 China

A new compact level-of-detail representation, called hierarchical surface fragments, for geometric objects with highly complex shape is presented. The representation comprises a set of irregular unstructured sampled surface fragments, whose boundary is a circle viewed along its normal. An efficient algorithm to construct the representation is described. In depiction of the framework for visualization, a screen tile technique for acceleration of rendering is proposed. Since an approximate z-buffer algorithm is adopted to fast determine visibility of each rendering primitive, a new buffer, z-delta-buffer, is designed to facilitate solving the problems raised by the approximation and to improve the image fidelity. Finally, a solution is provided to integrate our rendering approach for hierarchical surface fragments with traditional polygon-based methods.

关键词： rendering systems level of detail antialiasing image-based rendering.