Wyniki wyszukiwania - BazTech

1

Mesh construction based on differential surface property

Miyazaki R., Harada K.

Machine Graphics and Vision

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2006

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Vol. 15, No. 2

197-210

EN

In this paper, we propose a novel method for extraction of a feature from range data to create of a simplified triangular mesh. The feature extracted by our method is based on the surface property. In the past, vertices on a highly curved surface were extracted from range data, and the extracted vertices were triangulated to construct a simplified triangular mesh. However, the vertices extracted with such a method were not enough to create a simplified triangular mesh in some cases. For example, when the shape shows less change in one direction, like a parabolic shape, too many vertices are extracted by the traditional method. We introduce a surface property defined by a combination of the mean curvature and the gaussian curvature. Vertices are classified into three categories according to the surface property. Then, the structures consisting of vertices and edges are extracted suitably for constructing a simplified triangular mesh. Following that, we can create the desirable trianguiation through constrained Delaunay trianguiation using the extracted structures.

2

Metoda opisu brył przestrzennych z użyciem regułowej reprezentacji wiedzy

Turek M.

Automatyka / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2006

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T. 10, z. 3

571-578

PL

Artykuł prezentuje metodę przetwarzania obiektów z przestrzeni trójwymiarowej z wykorzystaniem, jako formy pośredniej struktur analogicznych do wiedzy bazującej na regułach. Zakodowanie niezbędnych do analizy brył informacji w takim formacie umożliwi redukcję ilości danych podlegających dalszej obróbce. Zaproponowana zostanie transformata, która będzie w stanie przeprowadzić zadaną bryłę (siatkę 3D) w opisywany zbiór reguł. Generalnie rzecz ujmując projektowana notacja ma na celu wychwycenie specjalnie wyselekcjonowanych punktów kluczowych każdej bryły oraz relacji między tymi punktami. Umożliwi to uproszczoną i szybką analizę brył w niektórych kierunkach, takich jak gabaryty bryły, czy selekcja komponentów, na które można ją naturalnie podzielić. Wynik analizy zawierał będzie informacje, mogące służyć do rozpoznawania bryły, obudowywania jej inną siatką (np. obrazującą tkaninę), czy szybkiej redukcji fragmentów bryły istotnej przykładowo przy renderowaniu w sporej odległości od obserwatora (z utratą detali).

EN

The article will discuss how to alternatively represent reduced information about 3D polygon meshes. It will propose a transformation able to convert provided 3D mesh into especially designed knowledge format. That format could be described as similar to a rule-based data. Each knowledge base will concentrate knowledge rules - with terms and conclusion specified. Each term will correspond to a point inside 3D mesh - considered by the transformation as important one. As the knowledge base is established a further part of analysis could be made. That part will just use achieved knowledge base as the only data source - providing information about mesh object dimensions, fragmentation or mesh simplification (alternate to mesh polygon reduction technique). The knowledge base can be easily stored, processed quickly, merged or manually edited - mostly because it is much smaller and perspicuous than a corresponding 3D mesh object.

3

Triangle mesh compression and simplification

Wu X., Li D.

Machine Graphics and Vision

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2002

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Vol. 11, No. 4

475-488

EN

Triangular meshes are widely used in computer graphics fields, such as GIS, CAD and VR. Very complex models, with hundreds of thousands of faces, are easily produced by curremt CAD tools, automatic acquisition devices, or by fitting isosurfaces out of volume datasets. Many geometric datasets require a larg amount of disk space. One of the solutions is to compress those large geometric data sets with geometric compression algorithms. On the other hand, a highly complex data representation is not always necessery. For example, a full size model is not required for generation of each frame of an interactive visualization. This has led to substantial research on the surface mesh compression or mesh simplification. We present a method to deal with both issues. It breaks down the triangle meshes into a set of triangle strips and vertex chains. Following that, inter-triangle-strip simplification and intra-triangle-strip simplification are used to simplify the meshes. The method can not only compress the mesh geometry datasets for hard disk storage, but also simplify the meshes for the purposes of rendering and displaying. The results show the validity and efficiency of our method.

4

Simplification of 3D head mesh acquired from laser scanner

Ye J.

Machine Graphics and Vision

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2002

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Vol. 11, No. 4

489-498

EN

Complex triangle meshes arise extensively in computer graphics. Such meshes greatly exceed the processing power of modern computer hardware and need to be simplified. The purpose of this paper is to simplify a 3D color human head mesh acquired from a 3D laser scanner. It is more important to keep the boundaries and quality of the sense organs which are the region of interest, while it is reasonable to simplify other features of the head aggressively, such as hair, face and neck. Based on these heuristics, we present a novel vertex merging mesh simplification algorithm based on region segmentation. The algorith can be divided into two stages: segmentation and simplification. First, the 3D color head mesh is segmented into different head parts with respect to both geometry and attributes, then vertices are classified into region-inner vertices and region-boundary vertices. Second, interative vertex merging is applied using region-weighted error metric in order to implement controllable simplifications. Results of several experiments are shown, demonstrating the potential of our method for a 3D color head mesh. Also, our method is resistant to noise in practical applications.