EG2006

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https://diglib.eg.org/handle/10.2312/253

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Using VTK as a Tool for Teaching and Applying Computer Graphics
(The Eurographics Association, 2006) Dias, Paulo; Madeira, Joaquim; Santos, Beatriz Sousa; Judy Brown and Werner Hansmann
During the first semester of 2005/2006 we used the Visualization Toolkit (VTK) as a tool for teaching and applying Computer Graphics, both for Computer Engineering students who chose to attend the 3D Modeling and Visualization course, and for M.Sc. students specializing in Computer Graphics. In both cases, students had not only to use VTK in about half of their lab classes, in order to accomplish some tasks and gain some knowledge on VTK s features and functionalities, but they were also required to develop a visualization application based on VTK. We describe first the motivation for using VTK in these two different scenarios, as well as the main course topics where we used the toolkit. Afterwards, we present some of the most successful projects developed by our students. Finally, we state some conclusions.
Evaluation Test for 3D Computer Graphics Content Production Capability based on Simulation Methodology
(The Eurographics Association, 2006) Miyai, Ayumi; Nakamura, Tagiru; Mikami, Koji; Kawashima, Motonobu; Yamaguchi, Yasushi; Judy Brown and Werner Hansmann
Through 15 years experience with the Certification Test of Computer Graphics by the Computer Graphic Arts Society, we have felt importance of a new style of test, namely simulation test (ST). The goal of ST is to evaluate the examinees knowledge and skills using simulation methodology. We conducted an experimental test session of ST in November 2005. In this experimental session, we also conducted a Paper and Pencil Test (PPT) for comparison. An assignment is shown to 75 testees by a storyboard. The testees read the storyboard, then, create answer work using ST software which we developed for this session. The testees would select and deploy characters, props, lights, and cameras, all of which has prepared to set parameters for the position, degree, focal length and etc. according to the timeline. The evaluation was conducted to check whether the testees' answer work is matched to the correct answer work. We analyzed results of both ST and PPT. We especially focused on the score difference and progress difference due to the level of proficiency of our testees operating ST software, and the correlation between their learning experiences and score, and on correlation between ST and PPT scores. From the results, we confirmed that the correlation between the scores of both ST and PPT was observed among all the testees, and that the scores of ST show the possibility of evaluating accumulation of skills of the testees to be able to brush up creativity for moving image content production with 3D computer graphics.
Exploring Flow Fields with GPU-Based Stream Tracers in Virtual Environments
(The Eurographics Association, 2006) Schirski, Marc; Bischof, Christian; Kuhlen, Torsten; Dieter Fellner and Charles Hansen
In this paper we present an immersive visualization approach for the intuitive exploration of flow fields, which operates entirely within the graphics subsystem. We augment particle data with a brief history of their recent positions, thus effectively computing and displaying animated tracers facilitating the understanding of the underlying flow field. Image quality is enhanced by employing a billboard-based rendering method for the particle trajectories simulating lit tubular geometry. This leads to significantly reduced depth perception problems and depth order ambiguities. Interactivity is maintained even for large amounts of tracers by shifting the computational load to the GPU. We alleviate 3D seed point specification problems by offering interaction mechanisms with full 6 degrees-of-freedom within an immersive virtual environment.
Developing Mobile 3D Applications with OpenGL ES and M3G
(The Eurographics Association, 2006) Pulli, K.; Vaarala, J.; Miettinen, V.; Aarnio, T.; Callow, M.; Nadia Magnenat-Thalmann and Katja Bühler
Mobile phones offer exciting new opportunities for graphics application developers. However, they also have significant limitations compared to traditional desktop graphics environments, including absence of dedicated graphics hardware, limited memory (both RAM and ROM), limited communications bandwidth, and lack of floating point hardware. Existing graphics APIs ignore these limitations and thus are infeasible to implement in embedded devices. This course presents two new 3D graphics APIs that address the special needs and constraints of mobile/embedded platforms: OpenGL ES and M3G. OpenGL ES is a light-weight version of the well-known workstation standard, offering a subset of OpenGL 1.5 capability plus support for fixed point arithmetic. M3G, Mobile 3D Graphics API for Java MIDP (Mobile Information Device Profile), also known as JSR-184, provides scene graph and animation support, binary file format, and immediate mode rendering that bypasses scene graphs. These APIs provide powerful graphics capabilities in a form that fits well on today s devices, and will support hardware acceleration in the future. The course begins with a discussion of the target environments and their limitations, and general techniques for coping with platform/environment constraints (such as fixed point arithmetic). This is followed by detailed presentations of the APIs. For each API, we describe the included functionality and compare it to related workstation standards, explaining what was left out and why. We also discuss practical aspects of working with the APIs on the target platforms, and present strategies for porting existing applications and creating new ones.
Simulating Drilling on Tetrahedral Meshes
(The Eurographics Association, 2006) Turini, G.; Ganovelli, F.; Montani, C.; Dieter Fellner and Charles Hansen
Bone drilling is a fundamental task in several surgical procedures, including mastoidectomy, cochlear implantation, orbital surgery. It consists in eroding the part of the bone in contact with the tip of the surgical tool when a sufficient pressure is exerted. Since the bone is an almost rigid material, the bone drilling simulations usually employ voxel-based representations of the bone, so that it is easy to show material removal by playing with material density in the voxels. Unfortunately, there are cases in which drilling is only a part of the task, and parts of the same object are also cut away or, worse, the bone is slightly deformable and therefore voxel-based representations do not work well. We propose a novel method to simulate drilling on objects represented explicitly by means of a tetrahedral mesh. The key idea of our method is to create an alternative representation of the tetrahedron when it is partially eroded. Such representation consists of a set of smaller tetrahedra obtained by a hierarchical decomposition of the original one, and combined to represent the current status of the erosion.
Magical Mirrors
(The Eurographics Association, 2006) Michelis, D.; Send, H.; Resatsch, F.; Schildhauer, T.; Dieter Fellner and Charles Hansen
This article describes the multi-media art installation MAGICAL MIRRORS with which the tradition of the mirror, as a medium of visual simulation, is carried over into the world of digital mediums. As theoretical framework, the basic principle of remediation as described by Bolter and Grusin is utilized. According to this theory new media technologies always represent the advancements of prior media that are either enhanced in order to upgrade the features or replaced entirely. MAGICAL MIRRORS follows in the tradition of the magical mirror found in palaces or amusement parks. Like their predecessors they awaken the curiosity of the viewer and invite him or her on a trip into virtual worlds.
A Breadth-First Approach for Teaching Computer Graphics
(The Eurographics Association, 2006) Domik, Gitta; Goetz, Frank; Judy Brown and Werner Hansmann
Two themes of computer graphics, namely computer-generated color and computer-generated visualization, are introduced in a teaching/learning tool using a breadth-first approach. The breadth-first approach provides a holistic view of the topics to teach, aids in interdisciplinary teaching and is equally motivating to male and female students. The breadth-first approach has now been used for several years and we can also report on evaluations of the teaching/learning tool.
Compter Graphics Education: Where and How Do We Develop Spatial Ability?
(The Eurographics Association, 2006) Mohler, James L.; Judy Brown and Werner Hansmann
This contribution provides an overview to the expansive research and literature concerning spatial ability. Its aim is to provide the reader with relevant historical and applied background and to make a call for computer graphics educators to focus on developing the spatial ability of computer graphics majors and non-majors. Spatial ability has broad applicability and provides a necessary area for computer graphics educators to contribute to the student development. Practical activities for the development of spatial ability are also provided.
Connectivity-Aware Sectional Visualization of 3D DTI Volumes using Perceptual Flat-Torus Coloring and Edge Rendering
(The Eurographics Association, 2006) Demiralp, Çagatay; Zhang, Song; Tate, David F.; Correia, Stephen; Laidlaw, David H.; Dieter Fellner and Charles Hansen
We present two new methods for visualizing cross-sections of 3D diffusion tensor magnetic resonance imaging (DTI) volumes. For each of the methods we show examples of visualizations of the corpus callosum in the midsagittal plane of several normal volunteers. In both methods, we start from points sampled on a regular grid on the cross-section and, from each point, generate integral curves in both directions following the principal eigenvector of the underlying diffusion tensor field.We compute an anatomically motivated pairwise distance measure between each pair of integral curves and assemble the measures to create a distance matrix. We next find a set of points in a plane that best preserves the calculated distances that are small each point in this plane represents one of the original integral curves. Our first visualization method wraps this planar representation onto a flat-torus and then projects that torus into a visible portion of a perceptually uniform color space (L*a*b*). The colors for the paths are used to color the corresponding grid points on the original cross-section. The resulting image shows larger changes in color where neighboring integral curves differ more. Our second visualization method lays out the grid points on the cross section and connects the neighboring points with edges that are rendered according to the distances between curves generated from these points. Both methods provide a way to visually segment 2D cross sections of DTI data. Also, a particular contribution of the coloring technique used in our first visualization method is to give a continuous 2D color mapping that provides approximate perceptual uniformity and can be repeated an arbitrary number of times in both directions to increase sensitivity.
Modern Parallel Coordinates
(The Eurographics Association, 2006) Inselberg, Alfred; Nadia Magnenat-Thalmann and Katja Bühler
The desire to augment our 3-dimensional perception and the need to understand multivariate problems spawned several multidimensional visualization methodologies. Understanding the underlying geometry of a multivariate problem provides insight into what is possible and what is not. After a short overview, Parallel Coordinates are introduced and developed rigorously showing, using new didactic software, how multidimensional lines, hyperplanes, flats, curves and smooth hypersurfaces can be visualized unambiguously. The development is interlaced with applications including Visual Data Mining (EDA) on real datasets (i.e. Feature extraction, GIS, Financial, Process Control, and others with hundreds of variables). There follow collision avoidance algorithms for air trafic control and detection of coplanarity and near-coplanarity with numerous applications. A geometric automatic classifier is applied to challenging clustering and classification problems. It provides the classification rule explicity and visually. Nonlinear VISUAL models in terms of hypersurfaces are constructed from data and used interactively for Decision Support discovering Feasibilites, Interelations, Sensitivities, enabling Constraint and Trade-Off Analysis. Our goal is to concentrate the relational information within a dataset into clear patterns eliminating the polygonal lines altogether. In view of recent results this prospect is becoming attainable as illustrated with a difficult problem central to many applications(Computer Vision, Geometric Modeling, Statistics).
Real Time Interactive Massive Model Visualization
(The Eurographics Association, 2006) Kasik, D.; Manocha, D.; Stephens, A.; Bruderlin, B.; Slusallek, P.; Gobbetti, E.; Correa, W.; Quilez, I.; Nadia Magnenat-Thalmann and Katja Bühler
Real-time interaction with complex models has always challenged interactive computer graphics. Such models can easily contain gigabytes of data. This tutorial covers state-of- the-art techniques that remove current memory and performance constraints. This allows a fundamental change in visualization systems: users can interact with huge models in real time.
Preface and Table of Contents
(The Eurographics Association, 2006) -; Dieter Fellner and Charles Hansen
Preface and Table of Contents
Articulated Video Sprites
(The Eurographics Association, 2006) Vanaken, C.; Gerrits, M.; Bekaert, P.; Dieter Fellner and Charles Hansen
In this paper, we present an extension to video sprites for articulated characters. Central to our technique is a matching cost which works on high-level 2D skeletal representations of the characters, instead of their visual appearance. Through a combination of different heuristics, we are able to animate a character according to a new sequence of target skeletons. This way we achieve an accurate matching and a hitherto unseen level of control over the video sprite.
Preface and Table of Contents
(The Eurographics Association, 2006) Magnenat-Thalmann, Nadia; Nadia Magnenat-Thalmann and Katja Bühler
Preface and Table of Contents
SpringLens Distributed Nonlinear Magnifications
(The Eurographics Association, 2006) Germer, T.; Götzelmann, T.; Spindler, M.; Strothotte, Th.; Dieter Fellner and Charles Hansen
We present a flexible, distributed and effective technique to model custom distortions of images. The main idea is to use a mass-spring model to create a flexible surface and to create distortions by changing the rest-lengths. A physical simulation works out the displacements of this particle grid. We provide intuitive tools to interactively design such nonlinear magnifications. In addition, our system enables data-driven distortions which allows us to use it for automatic nonlinear magnifications. We demonstrate this with an application for labeling of 3D scenes.
Teaching OpenGL Shaders: Hands-on, Interactive, and Immediate Feedback
(The Eurographics Association, 2006) Bailey, Mike; Judy Brown and Werner Hansmann
This paper describes the teaching of OpenGL shaders with hands-on a program called glman. Hands-on education is at its best when the students experimental feedback loop is very fast. glman allows students to create a shader scene description file which not only creates the 3D scene, but creates an interactive user interface to adjust parameters. Our experience in an experimental class taught in Spring 2006 is that glman is flexible enough to demonstrate and experiment with many shader concepts, and creates a fast learning curve for the students.
Evaluation of Different Diffuse Surface Reflection Models for Global Illumination
(The Eurographics Association, 2006) Diepstraten, Joachim; Borgo, Rita; Dieter Fellner and Charles Hansen
One common goal nearly all global illumination algorithms aim for is solving the light transport problem. The most visual noticeable one in the general case is the diffuse-diffuse light transport between surfaces. Most global illumination algorithms are very good at solving it. In many global illumination solutions the Lambertian diffuse surface reflection model is assumed. However, over the years several other diffuse models have been introduced mostly outside of the computer graphics community that according to their authors mimic real surface behaviour more accurately. In this paper we evaluate some of the better known models and place them into the context of solving global illumination problems.
Computational Photography
(The Eurographics Association, 2006) Raskar, Ramesh; Tumblin, Jack; Mohan, Ankit; Agrawal, Amit; Li, Yuanzen; Brian Wyvill and Alexander Wilkie
Computational photography combines plentiful computing, digital sensors, modern optics, actuators, probes and smart lights to escape the limitations of traditional film cameras and enables novel imaging applications. Unbounded dynamic range, variable focus, resolution, and depth of field, hints about shape, reflectance, and lighting, and new interactive forms of photos that are partly snapshots and partly videos are just some of the new applications found in Computational Photography. The computational techniques encompass methods from modification of imaging parameters during capture to sophisticated reconstructions from indirect measurements. We provide a practical guide to topics in image capture and manipulation methods for generating compelling pictures for computer graphics and for extracting scene properties for computer vision, with several examples. Many ideas in computational photography are still relatively new to digital artists and programmers and there is no upto- date reference text. A larger problem is that a multi-disciplinary field that combines ideas from computational methods and modern digital photography involves a steep learning curve. For example, photographers are not always familiar with advanced algorithms now emerging to capture high dynamic range images, but image processing researchers face difficulty in understanding the capture and noise issues in digital cameras. These topics, however, can be easily learned without extensive background. The goal of this STAR is to present both aspects in a compact form. The new capture methods include sophisticated sensors, electromechanical actuators and on-board processing. Examples include adaptation to sensed scene depth and illumination, taking multiple pictures by varying camera parameters or actively modifying the flash illumination parameters. A class of modern reconstruction methods is also emerging. The methods can achieve a photomontage by optimally fusing information from multiple images, improve signal to noise ratio and extract scene features such as depth edges. The STAR briefly reviews fundamental topics in digital imaging and then provides a practical guide to underlying techniques beyond image processing such as gradient domain operations, graph cuts, bilateral filters and optimizations. The participants learn about topics in image capture and manipulation methods for generating compelling pictures for computer graphics and for extracting scene properties for computer vision, with several examples. We hope to provide enough fundamentals to satisfy the technical specialist without intimidating the curious graphics researcher interested in recent advances in photography. The intended audience is photographers, digital artists, image processing programmers and vision researchers using or building applications for digital cameras or images. They will learn about camera fundamentals and powerful computational tools, along with many real world examples.
Rapid Modeling of Complex Building Façades
(The Eurographics Association, 2006) Finkenzeller, D.; Schmitt, A.; Dieter Fellner and Charles Hansen
Architectural settings occur in many virtual environments. Modeling such highly detailed structures manually is a time-consuming and tedious task. Therefore we propose a system for the rapid modeling of building façades. The designer just has to provide some coarse information, the building outline, its type and style and the computer takes care of creating the exact geometry. Adjacent architectural structures are adapted automatically, e. g. walls are adapted to exactly fit quoins made of different stone blocks. Also highly detailed façade elements like window frames made of single bricks, cornices, etc. are generated. Even at this point the designer can still interfere and change the building outline, the style, as well as window or door frame styles. Such a tool will relieve the designer of the burden of tedious, recurring and over all time-consuming modeling tasks.
Real-time Inhabited Virtual Worlds and Interaction - interactive virtual worlds module
(The Eurographics Association, 2006) Magnenat-Thalmann, Nadia; Papagiannakis, George; Egges, Arjan; Lyard, Etienne; Nadia Magnenat-Thalmann and Katja Bühler
Virtual Worlds [MK94] and their concept of cyber-real space interplay invoke such interactive digital narratives that promote new patterns of understanding. However, the "narrative" and "interactive" part, which refers to a set of events happening during a certain period of time and providing aesthetic, dramaturgical and emotional elements, objects and attitudes ([NM00], [TYK01]) is still an early topic of research. Mixing such aesthetic ambiences with interactive virtual character augmentations [CMM*03] and adding dramatic tension has developed very recently these narrative patterns into an exciting new edutainment medium [LHM03]. With the interplay of a modern real-time framework for integrated interactive virtual character simulation, we can enhance the experience with full virtual character simulations.

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