EG2000

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https://diglib.eg.org/handle/10.2312/218

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The 3D Model Acquisition Pipeline
(Eurographics Association, 2000) Bernardini, Fausto; Rushmeier, Holly
Three-dimensional image acquisition systems are rapidly becoming more affordable, especially systems based on commodity electronic cameras. At the same time, personal computers with graphics hardware capable of displaying complex 3D models are also becoming inexpensive enough to be available to a large population. As a result, there is potentially an opportunity to consider new virtual reality applications as diverse as cultural heritage and retail sales that will allow people to view realistic 3D objects on home computers. Although there are many physical techniques for acquiring 3D data – including laser scanners, structured light and time-of-flight – there is a basic pipeline of operations for taking the acquired data and producing a usable numerical model. We look at the fundamental problems of range image registration, line-of-sight errors, mesh integration, surface detail and color, and texture mapping. In the area of registration we consider both the problems of finding an initial global alignment using manual and automatic means, and refining this alignment with variations of the Iterative Closest Point methods. To account for scanner light-of-sight errors we compare averaging and conformance approaches. In the area of mesh integration, that is finding a single mesh joining the data from all scans, we compare various methods for computing interpolating and approximating surfaces. We then look at various ways in which surface properties such as color (more properly, spectral reflectance) can be extracted from acquired imagery. Finally, we examine techniques for a producing a final model representation that can be efficiently rendered using graphics hardware.
An Accurate Illumination Model for Objects Coated with Multilayer Films
(Eurographics Association, 2000) Hirayama, H.; Kaneda, K.; Yamashita, H.; Monden, Y.
This paper proposes an accurate illumination model for rendering objects coated with multilayer films. Optical phenomenaof multilayer films are caused by reflection, refraction, interference, and absorption of light inside each layer of multiple films, and these physical phenomena are complicatedly related with each other. The proposed method calculates composite reflectance and transmittance of multilayer films, taking into account all the physical phenomena described above, and visualizes the optical phenomena caused by the multilayer films accurately. The illumination model proposed in the paper can handle both smooth surface and locally smooth rough surfaces. Several examples of objects coated with various kinds of films demonstrate the usefulness of the proposed method.
Adding a scalar value to 2D vector field visualization: the BLIC (Bumped LIC)
(Eurographics Association, 2000) Sanna, A.; Montrucchio, B.
Visualization of vector data produced from application areas such as computational fluid dynamics (CFD), environmental sciences, and material engineering is a challenging task. Texture-based methods reveal to be effective, versatile, and suitable for a large spectrum of applications since they allow to obtain high resolution output textures where direction, orientation, and magnitude of the flow can be displayed. In this paper we present a new method called BLIC (Bumped LIC), which allows both to characterize and visualize interesting structures in the flow and to map an additional scalar value in the output texture by bumps and depressions, leaving colors for further information mapping. Some examples show how the proposed method can enhance the quality of output textures with respect to the classical texture-based approaches.
ALOHA : Adaptive Level Of Detail for Human Animation Towards a new framework
(Eurographics Association, 2000) Giang, Thanh; Mooney, Robert; Peters, Christopher; Sullivan, Carol O.
The task of animating and rendering virtual humans in real-time is challenging. One must first establish a sense of realism through appearance, and then maintain this realism through correct and plausible motion, while continually satisfying the real-time constraint imposed. One technique that aids in achieving such a task is to take advantage of the viewer’s perception to compute less accurate models when loss of accuracy is unlikely to be noticed. Traditionally, these ‘level of detail’ techniques have been used primarily for geometric modelling. However, more recently, they have also been applied to animation. This paper seeks to amalgamate animation and geometric level of detail research in order to produce an integrated framework on which to build a totally scalable system for virtual human animation.
Automatic Fitting of Digitised Contours at Multiple Scales through Curvature Scale Space
(Eurographics Association, 2000) Mokhtarian, Farzin; Ung, Yoke Khim
The Curvature Scale Space (CSS) technique has been used in conjunction with Hermite curves for automatic fitting of digitised contours at multiple scales. CSS is a powerful contour shape descriptor which is expected to be in the MPEG-7 standard. A parametric representation of the input contour is convolved with Gaussian functions in order to obtain multi-scale descriptions of the contour. Curvature can be computed directly at each point of the smoothed contours. As a result, a set of curvature zero-crossing points can be recovered from each smoothed contour. Hermite curves were used since each Hermite curve is defined by two endpoints and the tangent vectors at those points. No points external to the input contour are required for Hermite curves. Hermite endpoints are defined as consecutive curvature zero-crossing points extracted at multiple scales using the CSS method. Hermite tangent vectors can also be determined using the CSS technique. The only data stored are the endpoints and the tangent vectors needed by the Hermite curves in order to arrive at an approximate reconstruction of the original contour. Approximation Error and Compression Ratio are computed at each scale. The graph of compression ratio as a function of approximation error is smoothed to remove noise and small fluctuations. The bending point of that function is then defined as the largest maximum of its second derivative. The bending point can be considered as the boundary between the mostly vertical and the mostly horizontal segments of the graph. It can be used for automatic selection of an optimal scale.
Collaboration in VEs − fact or fiction?
(Eurographics Association, 2000) Hubbold, Roger J.
The growth of the Internet, and company intranets, fuelled by the promise of sophisticated on−line services, has raised expectations of rich collaborative virtual environments, in which humans can indulge in cooperative problem solving. Pioneering demonstrations, such as the work of NASA on rehearsing maintenance tasks for the Hubble telescope, and recent moves into on−line multi−user gaming, have given us a glimpse of what may be possible in a restricted context. And yet, for most users the reality is somewhat different. Interaction in virtual environments is hard enough with only a single user. Add to this the problems of multiple users, collaborating over a network, and we still seem some way from having a really useful, or even usable, tool. The problems span technology (faster, lower latency networks will help, but will not, by themselves solve the problem), software architectures (just how do we ensure a coherent view of a shared environment for multiple users?), to psychology and human factors (we need experiments to quantify how well things work). Above all, how do we come up with solutions which not only work but are accessible to, and usable by, ordinary programmers and end−users? In this talk I will explore some of these problems and describe our own attempts at addressing them.
Combining finite element deformation with cutting for surgery simulations
(Eurographics Association, 2000) Nienhuys, Han-Wen; van der Stappen, A. Frank
Interactive surgery simulations have conflicting requirements of speed and accuracy. In this paper we show how to combine a relatively accurate deformation model—the Finite Element (FE) method—and interactive cutting without requiring expensive matrix updates or precomputation. Our approach uses an iterative algorithm for an interactive linear FE deformation simulation. The iterative process requires no global precomputation, so runtime changes of the mesh, i.e. cuts, can be simulated efficiently. Cuts are performed along faces of the mesh; this prevents growth of the mesh. We present a provably correct method for changing the mesh topology, and a satisfactory heuristic for determining along which faces to perform cuts. The incision surface will be jagged; this problem is a subject of current research.
Component Based Human Animation Architecture
(Eurographics Association, 2000) Jing, Huang; Fi, Chin Kah; Prakash, Edmond C.
This paper describes a method to predict the free reach movement of different components of the human body. Since the human body is composed of the following components: arms, legs, torso, head & neck, and each of these components has similar features, the same geometric inverse kinematics algorithm can be used in different parts of the body to realize free reach movement task. The main advantage of the proposed method is that it avoids matrix inverse calculation, which is very time consuming. And by using this method, the task can be mostly simplified.
Dealing with Shape Complexity for Internet Access and Graphic Applications
(Eurographics Association, 2000) Rossignac, Jarek
Standard representations of 3D models are so verbose that only very simple models can be accessed over common communication links for immediate viewing. This situation is not likely to improve, since the need for more accurate 3D models and their deployment throughout a broader spectrum of industrial, scientific, and consumer application areas will outpace the improvements in transmission bandwidth to the office, home, or mobile worker or private user. Recently developed multi-resolution modeling technologies play an important role in addressing this bandwidth bottleneck, especially when combined with other approaches, such as intelligent culling, pre-fetching, and image-based rendering. This tutorial will discuss the details of compression, simplification, and progressive transmission techniques and of their interrelations.
Discrete Analysis for Antialiased Lines
(Eurographics Association, 2000) Boyer, V.; Bourdin, J. J.
This paper presents a new fast and smooth antialiasing technique. Drawing straight line is the graphic tool’s main primitive. Previous antialiasing techniques improve smoothness but slow down computation.
Efficient Evaluation of the Field Functions of Soft Objects Using Interval Tree
(Eurographics Association, 2000) Min, Kyung-Ha; Lee, In-Kwon; Park, Chan-Mo
We present an algorithm to evaluate the field function of a soft object efficiently. Instead of using a global field function that is defined by the sum of all local field functions, we consider only the set of local field functions that affects a point at which we want to evaluate the field function. To find the affecting local field functions efficiently, we exploit a data structure called interval tree based on the bounding volume of the component corresponding to the primitives (skeletons) of a soft object. The bounding volume of each component is generated with respect to the radius of a local field function of the component, threshold value, and the relations between the components and other neighboring components. The proposed scheme of field function evaluation can be used in many applications for soft objects such as modeling and rendering, especially in interactive modeling process.
A Facial Repertoire for Animation
(Eurographics Association, 2000) ten Hagen, Paul J. W.
Character design and facial animation of characters is among the most tedious parts of creation of animations. In contrast to body animations, performer data have not been successfully used for faces. The CharToon system provides a facility to create a powerful repertoire of reusable components at several levels for the construction of faces and face animations. The knowledge embedded in the system allows for reuse of facial architectures, motion methods and animation definitions for newly constructed or adapted faces. These methods cover among other things, expressions, speech animations and changing view points. This paper describes the organization of the repertoire, how it can be built and extended, and gives examples of its usage. The repertoire offers a perspective of how a higher level system of animation behaviors can be created on top. The presentation will show many animated examples of the contents and working of the repertoire.
Framework Technologies and Methods for Large Data Visualization
(Eurographics Association, 2000) Hewitt, W. T.; Curington,Ian
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Geometric Modeling Based on Polygonal Meshesv
(Eurographics Association, 2000) Kobbelt, Leif P.; Bischoff, Stephan; Botsch, Mario; Kähler, Kolja; Rössl, Christian; Schneider, Robert; Vorsatz, Jens
While traditional computer aided design (CAD) is mainly based on piecewise polynomial surface representations, the recent advances in the efficient handling of polygonal meshes have made available a set of powerful techniques which enable sophisticated modeling operations on freeform shapes. In this tutorial we are going to give a detailed introduction into the various techniques that have been proposed over the last years. Those techniques address important issues such as surface generation from discrete samples (e.g. laser scans) or from control meshes (ab initio design); complexity control by adjusting the level of detail of a given 3D-model to the current application or to the available hardware resources; advanced mesh optimization techniques that are based on the numerical simulation of physical material (e.g. membranes or thin plates) and finally the generation and modification of hierarchical representations which enable sophisticated multiresolution modeling functionality.
Geometric Signal Processing on Polygonal Meshes
(Eurographics Association, 2000) Taubin, G.
Very large polygonal models, which are used in more and more graphics applications today, are routinely generated by a variety of methods such as surface reconstruction algorithms from 3D scanned data, isosurface construction algorithms from volumetric data, and photogrametric methods from aerial photography. In this report we provide an overview of several closely related methods developed during the last few yers, to smooth, denoise, edit, compress, transmit, and animate very large polygonal models.
An Image Processing Approach to Detection of Ridges and Ravines on Polygonal Surfaces
(Eurographics Association, 2000) Belyaev, Alexander; Ohtake, Yutaka
Surface creases, ridges and ravines, provide us with important information about the shapes of 3D objects and can be intuitively defined as curves on a surface along which the surface bends sharply. Exploring similarity between edges of 2D grey-scale images and curvature extrema of 3D shapes and generalizing a basic edge detection approach to triangular meshes, we develop a method for detection of ridges and ravines on a smooth surface approximated by a triangular mesh. We also sketch three potential applications of our approach: mesh fairness evaluation, improving mesh decimation techniques, and simulating artistic pen-and-ink drawings of 3D objects.
Imaging Geometry for Concentric Mosaics
(Eurographics Association, 2000) Watson, G. C.; Vaughan, N.; Wright, M. W.
Image-based models of environments can be captured with the use of a rotating video camera. In this paper we consider the nature of the display to develop a simple quantitative measure of the quality of ray sampling which we use to compare different imaging geometries for concentric mosaics. We propose a novel arrangement for the rotating camera, which we show to produce a better sampling of rays for viewing on displays where the display surface is fixed in space and the view position is varied. We show how this improved capture geometry can be employed in a head tracked display to produce a display that resembles a virtual window through which a captured environment can be viewed.
Interactive 3D Rendering and Visualization in Networked Environments
(Eurographics Association, 2000) Martin, Ioana M.; Klosowski, James T.; Horn, William P.
Efficient delivery of 3D graphics over networks is becoming increasingly important for a number of applications, ranging from industrial design and manufacturing to entertainment. As companiesmake the transition from a conventional business model to an e-business model, the number of users that require access to 3D model databases is forecast to grow dramatically over the next few years.While some usersmay access these databases using highperformance graphics hardware over high-speed connections, others are likely to access the data with devices having limited hardware graphics support over slower connections such as busy intranets, dial-in networks, or wireless connections. In this context, there is a requirement for efficiency. This translates into ensuring that access to centralized data is provided through a unified interface cognizant of the environment conditions and capable of transparently adjusting the access mechanism in order to provide the clients with optimal access service. In this course, attendees will learn to leverage existing methods for data transfer and interactive graphics to create the next generation of 3D networked graphics software tools.
Interactive Display of Global Illumination Solutions for Non-Diffuse Environments
(Eurographics Association, 2000) Heidrich, Wolfgang
In recent years there has been a lot of work on interactively displaying global illumination solutions for nondiffuse environments. This is an extremely active field of research, in which a lot of different approaches have been proposed recently. In this State-of-The-Art-Report, we will discuss and compare these. This will hopefully lay the ground for systematically addressing the open questions in the future.
Interactive Modelling of Convolution Surfaces with an Extendable User Interface
(Eurographics Association, 2000) Goto, Yuichiro; Pasko, Alexander
Convolution surfaces enable the user to model complex free-form shapes. Due to analytical solutions for some kernel functions and skeletal elements, it is possible to model convolution surfaces interactively. An extendable user interface allows the user to design models using different types of convolution surfaces. New primitives can be easily bound to the modeller using the proposed binding technique. Models generated in HyperFun language can be exchanged between modelling tools on several platforms.

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