Masaki Aono

Watermarking three-dimensional polygonal models through geometric and topological modifications

This paper discusses techniques for embedding data into three-dimensional (3-D) polygonal models of geometry. Given objects consisting of points, lines, (connected) polygons, or curved surfaces, the algorithms described in produce polygonal models with data embedded into either their vertex coordinates, their vertex topology (connectivity), or both. Such data embedding can be used, for example, for copyright notification, copyright protection, theft deterrence, and inventory of 3-D polygonal models. A description of the background and requirements is followed by a discussion of where, and by what fundamental methods, data can be embedded into 3-D polygonal models. The paper then presents several data embedding algorithms, with examples, based on these fundamental methods. By means of these algorithms and examples, we show that the embedding of data into 3-D polygonal models is a practicable technique.

Botanical Tree Image Generation

It may be true, as the poet said, that ¿...only God can make a tree,¿ but through geometric modeling a computer graphics system can produce a remarkable likeness.

Watermaking three-dimensional polygonal models

The advantages of digital media such as the Internet and CD-ROMs lie in the fact that their contents are easy to duplicate, edit, and distribute. These advantages, however, are double-edged swords, because they also facilitate unauthorized use of such contents. Data embedding, which places information into the contents themselves, is an approach to address this issue. Embedded information can be used, for example, for copyright protection, theft deterrence, and inventory. This paper discusses our work on embedding data into three-dimensional (3D) polygonal models of geometry. Given objects consisting of points, lines, polygons, or curved surfaces, the data embedding algorithms described in this paper produce polygonal models with data embedded. Data are placed into 3D polygonal models by modifying either their vertex coordinates, their vertex topology (connectivity), or both. A brief review of related work and a description of the requirements of data embedding is followed by a discussion of where, and by what fundamental methods, data can be embedded into 3D polygonal models. The paper then presents data-embedding algorithms, with examples, based on these fundamental methods. Additional

Data embedding algorithms for geometrical and non-geometrical targets in three-dimensional polygonal models

Three-dimensional (3D) graphics is about to become a full-fledged multimedia data type, prompted by the increasing popularity of virtual reality modeling language (VRML) [15]and imminent standardization of MPEG-4 [16]. This paper presents several algorithms for embedding data in triangular meshes, arguably the most important component in both VRML and MPEG-4 in defining arbitrary shapes. A topology-modifying algorithm described in this paper embeds bit string in connectivity of triangles, while another algorithm cuts out patterns from a mesh. Yet another algorithm modifies texture coordinate, a non-geometrical quantity, for embedding. Watermarks embedded in 3D graphics contents could be used as a tool in managing intellectual property and other issues associated with these contents.

A wrinkle propagation model for cloth

This paper focuses on a physically based non-rigid object model for the behavior of cloth, and its simulation with given forces and boundary conditions. The fundamental model is based on the equilibrium equation in the field of elasticity theory and on D’Alembert’s principle. The model is enhanced by taking account of the damping factor, the anisotropic factor, and the modified constitutive equations between strain and stress, specifically viscoelastic factors for both static and dynamic forces. These enhancements greatly increase the flexibility of the model, and result in a capability for expressing very natural “wrinkles” in cloth. Since this model inherently includes differentials with respect to time, animation is easily attained.

Fitting a woven-cloth model to a curved surface: mapping algorithms

Abstract The problem of fitting a 2D broadcloth composite ply (modelled as a piece of deformable woven cloth) onto a 3D curved surface (modelled with a NURBS surface) is considered. ‘Fitting’ means that a ply is deformed and applied to a surface so that it is everywhere in contact with the surface. A fitting method is presented that incorporates a flexible method for specifying initial conditions, and allows for the simulation of a wide range of fitting configurations.

SHREC'12 track: generic 3D shape retrieval

Generic 3D shape retrieval is a fundamental research area in the field of content-based 3D model retrieval. The aim of this track is to measure and compare the performance of generic 3D shape retrieval methods implemented by different participants over the world. The track is based on a new generic 3D shape benchmark, which contains 1200 triangle meshes that are equally classified into 60 categories. In this track, 16 runs have been submitted by 5 groups and their retrieval accuracies were evaluated using 7 commonly used performance metrics.

Extracting spatial knowledge from the web

The content of the World-Wide Web is pervaded by information of a geographical or spatial nature, particularly location information such as addresses, postal codes, and telephone numbers. We present a system for extracting spatial knowledge from collections of Web pages gathered by Web-crawling programs. For each page determined to contain location information, we apply geocoding techniques to compute geographic coordinates, such as latitude-longitude pairs. Next, we augment the location information with keyword descriptors extracted from Web page contents. We then apply spatial data mining techniques on the augmented location information to derive spatial knowledge.

Embedding Data in 3D Models

The recent popularity of digital media such as CD-ROM and the Internet has prompted exploration of techniques for embedding data, either visibly or invisibly, into text, image, and audio objects. Applications of such data embedding include copyright identification, theft deterrence, and inventory.

Multi-Fourier spectra descriptor and augmentation with spectral clustering for 3D shape retrieval

We propose a new method of similarity search for 3D shape models, given an arbitrary 3D shape as a query. The method features the high search performance enabled in part by our unique feature vector called Multi-Fourier Spectra Descriptor (MFSD), and in part by augmenting the feature vector with spectral clustering. The MFSD is composed of four independent Fourier spectra with periphery enhancement. It allows us to faithfully capture the inherent characteristics of an arbitrary 3D shape object regardless of the dimension, orientation, and original location of the object when it is first defined. Given a 3D shape database, the augmentation with spectral clustering is done first by computing the p-minimum spanning tree of the whole data set, where p is a number usually much less than m, the size of the whole 3D shape data set. We then define the affinity matrix, which is a square matrix of size m by m, where each element of the matrix denotes the distance between two shape objects. The distance is computed in advance by traversing the p-minimum spanning tree. The eigenvalue decomposition is then applied to the affinity matrix to reduce dimensionality of the matrix, followed by grouping into k clusters. The cluster information is kept for augmenting the search performance when a query is given. With a series of benchmark data sets, we will demonstrate that our approach outperforms previously known methods for 3D shape retrieval.