LEVEL OF DETAIL AND MULTI-RESOLUTION MODELING FOR VIRTUAL PROTOTYPING

2001 ◽  
Vol 01 (02) ◽  
pp. 329-343 ◽  
Author(s):  
ZHIGENG PAN ◽  
MINGMIN ZHANG ◽  
KUN ZHOU ◽  
CHIYI CHENG ◽  
JIAOYING SHI
Keyword(s):  
Virtual Reality ◽  
Large Scale ◽  
Virtual Prototyping ◽  
Level Of Detail ◽  
Data Sets ◽  
Virtual Design ◽  
Resolution Model ◽  
Cad Models ◽  
Speed Up ◽  
Representation Scheme

Reconciling scene realism with interactivity has emerged as one of the most important areas in making virtual reality feasible for large-scale CAD data sets consisting of several millions of primitives. Level of detail (LoD) and multi-resolution modeling techniques in virtual reality can be used to speed up the process of virtual design and virtual prototyping. In this paper, we present an automatic LoD generation and rendering algorithm, which is suitable for CAD models and propose a new multi-resolution representation scheme called MRM (multi-resolution model), which can support efficient extraction of fixed resolution and variable resolution for multiple objects in the same scene. MRM scheme supports unified selective simplifications and selective refinements over the mesh. Furthermore, LoD and multi-resolution models may be used to support real-time geometric transmission in collaborative virtual design and prototyping.

Level of Detail and Multi-Resolution Modeling Techniques for Virtual Design and Prototyping

1999 ◽  
Author(s):  
Zhigeng Pan ◽  
Kun Zhou ◽  
Chiyi Cheng ◽  
Mingmin Zhang
Keyword(s):  
Virtual Reality ◽  
Large Scale ◽  
Level Of Detail ◽  
Data Sets ◽  
Virtual Design ◽  
Variable Resolution ◽  
Modeling Techniques ◽  
Resolution Model ◽  
Cad Models ◽  
Representation Scheme

Abstract Reconciling scene realism with interactivity has emerged as one of the most important areas in making virtual reality feasible for large-scale CAD data sets consisting of several millions of primitives. Level of detail (LoD) and multi-resolution modeling techniques in virtual reality can be used to speedup the process of virtual design and virtual prototyping. In this paper we present an automatic LoD generation and rendering algorithm which is suitable for CAD models and propose a new multi-resolution representation scheme called MRM (multi-resolution model), which can support efficient extraction of fixed resolution and variable resolution for multiple objects in the same scene. MRM scheme supports unified selective simplifications and selective refinements over the mesh. Furthermore, LoD and multi-resolution models may be used to support real-time geometric transmission in collaborative virtual design and prototyping.

scholarly journals Multi-Resolution Modeling for Virtual Design

2000 ◽  
Vol 4 (4) ◽  
pp. 110-120 ◽  
Author(s):  
Chiyi Cheng ◽  
Mingmin Zhang ◽  
Zhigeng Pan
Keyword(s):  
Virtual Reality ◽  
Virtual Prototyping ◽  
Virtual Design ◽  
Multiple Objects ◽  
Variable Resolution ◽  
Modeling Techniques ◽  
Efficient Extraction ◽  
Key Features ◽  
Modeling Data ◽  
Representation Scheme

The benefits of multi-resolution modeling techniques in virtual reality are vast, but one essential component of this model is how it can be used to speedup the process of virtual design and virtual prototyping. In this paper we propose a new multi-resolution representation scheme called MRM, which can support efficient extraction of both fixed and variable resolution modeling data for handling multiple objects in the same scene. One important feature of the MRM scheme is that it supports unified selective simplifications and selective refinements over the mesh representation of the object. In addition, multi-resolution models may be used to support real-time geometric transmission of data in collaborative virtual design and prototyping applications. These key features in MRM, may be applied to a variety of VR applications.

Model Abstraction Techniques for Virtual Prototyping

1996 ◽  
Author(s):  
Jyun-Ming Chen ◽  
Chih-Chang Hsieh
Keyword(s):  
Virtual Reality ◽  
Virtual Prototyping ◽  
Level Of Detail ◽  
Design Stage ◽  
Model Simplification ◽  
Virtual Reality Technology ◽  
Model Abstraction ◽  
Level Of Details ◽  
Cad Cam ◽  
Simplification Techniques

Abstract The incorporation of VR (virtual reality) technology in the CAD/CAM community shows a promising future. Virtual prototyping uses VR techniques to simulate various functionalities of a candidate design. Downstream aspects of the product can be examined early at the design stage, saving the time and money required for repetitive design iterations. Real-time rendering is essential for interactive VR applications. This is especially challenging when dealing with complex geometric databases. Various methods have been proposed in the literature to tackle this problem. Level-of-details is a methodology that incorporates multiple representations of a model in the viewing environment. It reduces the rendering load by presenting the model in the most appropriate level of detail. However, these simplified representations often require laborious redesign efforts. In this paper, several model simplification techniques are reviewed. An automatic simplification procedure for CSG models is also devised. This method incorporates both the geometric simplification and the dimensional reduction schemes. Implemented on a non-manifold topological kernel, the system has been shown to produce promising results.

The Principle and Process of Digital Fabrication of Biomedical Objects

2018 ◽  
pp. 505-520
Author(s):  
S. H. Choi ◽  
H. H. Cheung ◽  
W. K. Zhu
Keyword(s):  
Virtual Reality ◽  
Biomedical Engineering ◽  
Virtual Prototyping ◽  
Digital Fabrication ◽  
Manufacturing Processes ◽  
Body Parts ◽  
Human Organs ◽  
Cad Models ◽  
Traditional Manufacturing ◽  
Bone Structures

Biomedical objects are used as prostheses to repair damaged bone structures and missing body parts, as well as to study complex human organs and plan surgical procedures. They are, however, not economical to make by traditional manufacturing processes. Researchers have therefore explored the multi-material layered manufacturing (MMLM) technology to fabricate biomedical objects from CAD models. Yet, current MMLM systems remain experimental with limited practicality; they are slow, expensive, and can only handle small, simple objects. To address these limitations, this chapter presents the multi-material virtual prototyping (MMVP) technology for digital fabrication of complex biomedical objects cost-effectively. MMVP integrates MMLM with virtual reality to fabricate biomedical objects for stereoscopic visualisation and analyses to serve biomedical engineering purposes. This chapter describes the principle of MMVP and the processes of digital fabrication of biomedical objects. Case studies are presented to demonstrate these processes and their applications in biomedical engineering.

Virtual Prototyping Analysis on Gear Assembly of the Power Train for a Large-Scale Combine Harvester

2013 ◽  
Vol 441 ◽  
pp. 635-640
Author(s):  
Zhong Xiang Zhu ◽  
Zhen Li ◽  
Bin Xie ◽  
En Rong Mao
Keyword(s):  
Large Scale ◽  
Virtual Prototyping ◽  
Operating Speed ◽  
Power Train ◽  
Cad Models ◽  
Combine Harvester ◽  
Simulation Results ◽  
Precise Simulation ◽  
Vital Factor

Stabilization of the operating speed is a vital factor that affects a combine harvester's productivity. In this paper, the pretreatment of CAD models is set for precise simulation. Using CAE tools, the research concentrates on the static and kinematic characters of the gear assembly in the power train. Ultimately, the comparisons of the simulation results with the theoretical ones are conducted. The results indicate that the designed gear assembly can remain the operating speed stable and reliable under the assumed condition.

scholarly journals SwiftOrtho: A fast, memory-efficient, multiple genome orthology classifier

GigaScience ◽  
2019 ◽  
Vol 8 (10) ◽  
Author(s):  
Xiao Hu ◽  
Iddo Friedberg
Keyword(s):  
Protein Function ◽  
Large Scale ◽  
Homology Search ◽  
Comparative Genomic ◽  
Data Sets ◽  
Analysis Tool ◽  
Memory Usage ◽  
Spaced Seeds ◽  
Speed Up ◽  
Genome Analyses

Abstract Background Gene homology type classification is required for many types of genome analyses, including comparative genomics, phylogenetics, and protein function annotation. Consequently, a large variety of tools have been developed to perform homology classification across genomes of different species. However, when applied to large genomic data sets, these tools require high memory and CPU usage, typically available only in computational clusters. Findings Here we present a new graph-based orthology analysis tool, SwiftOrtho, which is optimized for speed and memory usage when applied to large-scale data. SwiftOrtho uses long k-mers to speed up homology search, while using a reduced amino acid alphabet and spaced seeds to compensate for the loss of sensitivity due to long k-mers. In addition, it uses an affinity propagation algorithm to reduce the memory usage when clustering large-scale orthology relationships into orthologous groups. In our tests, SwiftOrtho was the only tool that completed orthology analysis of proteins from 1,760 bacterial genomes on a computer with only 4 GB RAM. Using various standard orthology data sets, we also show that SwiftOrtho has a high accuracy. Conclusions SwiftOrtho enables the accurate comparative genomic analyses of thousands of genomes using low-memory computers. SwiftOrtho is available at https://github.com/Rinoahu/SwiftOrtho

Limits of the WTQ method for calculating momentum flux

2020 ◽  
Author(s):  
Peter Preusse ◽  
Markus Geldenhuys ◽  
Manfred Ern
Keyword(s):  
Gravity Wave ◽  
Momentum Flux ◽  
Large Scale ◽  
Vertical Gradient ◽  
Data Sets ◽  
Flux Vector ◽  
Intrinsic Frequency ◽  
Single Wave ◽  
Resolution Model ◽  
High Resolution Model

<p>The acceleration of the large scale circulation by gravity wave is commonly described via the vertical gradient of the vertical flux of horizontal pseudomomentum, or in short of the momentum flux. The momentum flux vector is given by</p><p> (F<sub>px</sub>,F<sub>py</sub>) = (1-f<sup>2</sup>/ω<sup>2</sup>) ( <u'w'>,<v'w'>)</p><p>where < > describes the spatial or temporal mean of at least one wavelength or period of the gravity wave. If one is going actually to calculate momentum flux from an observation or high-resolution model, several difficulties arise. First, one has to know the intrinsic frequency ω of the wave, second one tacitly assumes that only a single wave is causing the wind perturbations u', v' and w', and third one needs to find an appropriate averaging interval. One possibility to solve this is to perform spectral analysis. An alternative was introduced by Geller et al. (2013) which, based on the polarization relations, infers ω directly from the perturbation wind temperature quadratics and is hence referred to as WTQ. In a brief study we will investigate the implication of the single wave assumption for the momentum flux calculated from data sets calculating multiple waves.</p>

scholarly journals Galaxy spin direction distribution in HST and SDSS show similar large-scale asymmetry

2020 ◽  
Vol 37 ◽  
Author(s):  
Lior Shamir
Keyword(s):  
Large Scale ◽  
Spiral Galaxies ◽  
Hubble Space Telescope ◽  
Gravitational Interaction ◽  
Large Data ◽  
Sloan Digital Sky Survey ◽  
Data Sets ◽  
Dipole Axis ◽  
Data Set ◽  
The Asymmetry

Abstract Several recent observations using large data sets of galaxies showed non-random distribution of the spin directions of spiral galaxies, even when the galaxies are too far from each other to have gravitational interaction. Here, a data set of $\sim8.7\cdot10^3$ spiral galaxies imaged by Hubble Space Telescope (HST) is used to test and profile a possible asymmetry between galaxy spin directions. The asymmetry between galaxies with opposite spin directions is compared to the asymmetry of galaxies from the Sloan Digital Sky Survey. The two data sets contain different galaxies at different redshift ranges, and each data set was annotated using a different annotation method. The results show that both data sets show a similar asymmetry in the COSMOS field, which is covered by both telescopes. Fitting the asymmetry of the galaxies to cosine dependence shows a dipole axis with probabilities of $\sim2.8\sigma$ and $\sim7.38\sigma$ in HST and SDSS, respectively. The most likely dipole axis identified in the HST galaxies is at $(\alpha=78^{\rm o},\delta=47^{\rm o})$ and is well within the $1\sigma$ error range compared to the location of the most likely dipole axis in the SDSS galaxies with $z>0.15$ , identified at $(\alpha=71^{\rm o},\delta=61^{\rm o})$ .

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