Algorithms for Mesh Simplification

Práce se zabývá použitím OpenSceneGraphu, nástroji pro LOD a algoritmy pro zjednodušování modelů. Výsledkem je prototyp hry a aplikace pro demonstraci algoritmů.The topic of the thesis is using of OpenSceneGraph, tools for LOD and algorithms for mesh simplification. The result is a game prototype and a program for demonstrating algorithms.

An Accelerating 3D Image Reconstruction System Based on the Level-of-Detail Algorithm

This paper proposes a research of An Accelerating 3D Image Reconstruction System Based on the Level-of-Detail Algorithm and combines 3D graphic application interfaces, such as DirectX3D and OpenCV to reconstruct the 3D imaging system for Magnetic Resonance Imaging (MRI), and adds Level of Detail (LOD) algorithm to the system. The system uses the volume rendering method to perform 3D reconstruction for brain imaging. The process, which is based on the level of detail algorithm that converts and formulates functions from differing levels of detail and scope, significantly reduces the complexity of required processing and computation, under the premises of maintaining drawing quality. To validate the system's efficiency enhancement on brain imaging reconstruction, this study operates the system on various computer platforms, and uses multiple sets of data to perform rendering and 3D object imaging reconstruction, the results of which are then verified and compared

Mesh simplification with hierarchical shape analysis and iterative edge contraction

2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

A new method for simplification and compression of 3D meshes

We focus on the lossy compression of manifold triangle meshes. Our SwingWrapper approach partitions the surface of an original mesh M into simply-connected regions, called triangloids. We compute a new mesh M\u27. Each triangle of M\u27 is a close approximation of a pseudo-triangle of M. By construction, the connectivity of M\u27 is fairly regular and can be compressed to less than a bit per triangle using EdgeBreaker or one of the other recently developed schemes. The locations of the vertices of M\u27 are compactly encoded with our new prediction scheme, which uses a single correction parameter per vertex. For example, a variety of popular models retiled with our approach yield 10 times fewer triangles without exceeding an error of 1% of the radius of the bounding ball. Vertices of M\u27 are encoded with an average of 6 bits, which results in a total storage of 0.4 bits per triangle of the original mesh. The proposed solution may also be used to encode crude meshes for adaptive transmission and for controlling subdivision surfaces

Polygonal Models Decimation

Při reprezentaci objektů pomocí polygonálních modelů často vznikají modely obsahující velmi vysoké množství polygonů. Pokud chceme pracovat s takovým modelem v reálném čase, tak je nutné ho zjednodušit.Proces zjednodušování modelu se nazývá decimace. Je známých několik decimačních metod pro zjednodušení modelů. Podle charakteristiky modelu a požadovaných vlastností zjednodušenného modelu chceme vybrat vhodnou metodu, proto je nutné znát vlastnosti jednotlivých metod a také jejich omezení.When representing objects with polygonal models, we must often use models consisting of large number of polygons. If we want to work in real time with such model the model must be simplificated. The process of simplification is called decimation. We know several decimation techniques for simplification of models. According to characteristics of model and target features of simplified model, we want to choose suitable method. So we need to know characteristics of particular methods and also their limits.

3D Mesh Simplification. A survey of algorithms and CAD model simplification tests

Simplification of highly detailed CAD models is an important step when CAD models are visualized or by other means utilized in augmented reality applications. Without simplification, CAD models may cause severe processing and storage is- sues especially in mobile devices. In addition, simplified models may have other advantages like better visual clarity or improved reliability when used for visual pose tracking. The geometry of CAD models is invariably presented in form of a 3D mesh. In this paper, we survey mesh simplification algorithms in general and focus especially to algorithms that can be used to simplify CAD models. We test some commonly known algorithms with real world CAD data and characterize some new CAD related simplification algorithms that have not been surveyed in previous mesh simplification reviews.Siirretty Doriast

A Constrained Resampling Strategy for Mesh Improvement

In many geometry processing applications, it is required to improve an initial mesh in terms of multiple quality objectives. Despite the availability of several mesh generation algorithms with provable guarantees, such generated meshes may only satisfy a subset of the objectives. The conflicting nature of such objectives makes it challenging to establish similar guarantees for each combination, e.g., angle bounds and vertex count. In this paper, we describe a versatile strategy for mesh improvement by interpreting quality objectives as spatial constraints on resampling and develop a toolbox of local operators to improve the mesh while preserving desirable properties. Our strategy judiciously combines smoothing and transformation techniques allowing increased flexibility to practically achieve multiple objectives simultaneously.  We apply our strategy to both planar and surface meshes demonstrating how to simplify Delaunay meshes while preserving element quality, eliminate all obtuse angles in a complex mesh, and maximize the shortest edge length in a Voronoi tessellation far better than the state-of-the-art

Perceived quality assessment in object-space for animated 3D models

Ankara : The Department of Computer Engineering and the Graduate School of Engineering and Science of Bilkent University, 2012.Thesis (Master's) -- Bilkent University, 2012.Includes bibliographical refences.Computational models and methods to handle 3D graphics objects continue to emerge with the wide-range use of 3D models and rapid development of computer graphics technology. Many 3D model modification methods exist to improve computation and transfer time of 3D models in real-time computer graphics applications. Providing user with the least visually-deformed model is essential for 3D modification tasks. In this thesis, we propose a method to estimate the visually perceived differences on animated 3D models. The model makes use of Human Visual System models to mimic visual perception. It can also be used to generate a 3D sensitivity map for a model to act as a guide during the application of modifications. Our approach gives a perceived quality measure using 3D geometric representation by incorporating two factors of Human Visual System (HVS) that contribute to perception of differences. First, spatial processing of human vision model enables us to predict deformations on the surface. Secondly, temporal effects of animation velocity are predicted. Psychophysical experiment data is used for both of these HVS models. We used subjective experiments to verify the validity of our proposed method.Yakut, Işıl DoğaM.S