GRAPP 2016 Abstracts


Area 1 - Geometry and Modeling

Full Papers
Paper Nr: 9
Title:

Efficient Culling Techniques for Interactive Deformable NURBS Surfaces on GPU

Authors:

Raquel Concheiro, Margarita Amor, Emilio J. Padrón and Michael Doggett

Abstract: NURBS (Non-uniform rational B-splines) surfaces are the standard freeform representation in Computer-Aided Design (CAD) applications. Rendering NURBS surfaces accurately while they are interactively manipulated and deformed is a challenging task. In order to achieve it, the elimination from pipeline in early stages of back-facing surfaces or surface pieces is a key advantage. Furthermore, an effective interactive manipulation implies that all the culling computations should be performed for each frame, facing the possibility of fast changes in occlusion information. In this paper, different interactive culling strategies for NURBS surfaces are presented and analyzed. These culling techniques are based on the exploitation of the geometric properties presented in a NURBS surface, that allow easily to find bounds for it in screen space for each frame. Furthermore, the culling overhead for our proposals is small compared to the computational saving, outperforming a proposal without culling. An implementation of these strategies using current GPUs is presented, achieving real-time and interactive rendering rates of complex parametric models.

Paper Nr: 10
Title:

Multi-Class Error-Diffusion with Blue-noise Property

Authors:

Xiaoliang Xiong, Haoli Fan, Jie Feng, Zhihong Liu and Bingfeng Zhou

Abstract: Existing researches on error-diffusion mainly focus on sampling over a single channel of input signal. But there are cases where multiple channels of signal need to be sampled simultaneously while keeping their blue-noise property for each individual channel as well as their superimposition. To solve this problem, we propose a novel discrete sampling algorithm called Multi-Class Error Diffusion (MCED). The algorithm couples multiple processes of error diffusion to maintain a sampling output with blue-noise distribution. The correlation among the classes are considered and a threshold displacement is introduced into each process of error-diffusion for solving the sampling conflicts. To minimize the destruction to the blue-noise property, an optimization method is used to find a set of optimal key threshold displacements. Experiments demonstrate that our MCED algorithm is able to generate satisfactory multi-class sampling output. Several application cases including color image halftoning and vectorization are also explored.

Paper Nr: 16
Title:

Re-parameterization of a Deformation Model for Non-rigid Registration

Authors:

Van-Toan Cao, Trung-Thien Tran and Denis Laurendeau

Abstract: In this paper we present a method for non-rigid registration of meshes. The method aligns two surfaces of deformable objects by automatically separating the deformation into a single global transformation and other local deformations. The local deformations are found by applying the deformation model proposed by Sumner (Sumner et al., 2007) that previous methods have used to register two surfaces. However, we specify a rigid transformation for each node of the deformation graph using a rotation matrix and a translation vector. With this model, unit quaternions of rotation matrices are paramterized using an homeomorphic relation between the 4D unit sphere and the 3D projective space. Therefore, the number of unknowns is reduced by half compared to the original models based on affine transformations and the optimization process is less complex. We demonstrate the efficiency of the proposed method by aligning the surfaces of data sets without any prior knowledge and assumptions about the deformation between the two surfaces.

Paper Nr: 21
Title:

Copula Eigenfaces - Semiparametric Principal Component Analysis for Facial Appearance Modeling

Authors:

Bernhard Egger, Dinu Kaufmann, Sandro Schönborn, Volker Roth and Thomas Vetter

Abstract: Principal component analysis is a ubiquitous method in parametric appearance modeling for describing dependency and variance in a data set. The method requires that the observed data be Gaussian-distributed. We show that this requirement is not fulfilled in the context of analysis and synthesis of facial appearance. The model mismatch leads to unnatural artifacts which are severe to human perception. In order to prevent these artifacts, we propose to use a semiparametric Gaussian copula model, where dependency and variance are modeled separately. The Gaussian copula enables us to use arbitrary Gaussian and non-Gaussian marginal distributions. The new flexibility provides scale invariance and robustness to outliers as well as a higher specificity in generated images. Moreover, the new model makes possible a combined analysis of facial appearance and shape data. In practice, the proposed model can easily enhance the performance obtained by principal component analysis in existing pipelines: The steps for analysis and synthesis can be implemented as convenient pre- and post-processing steps.

Paper Nr: 26
Title:

Generating Straight Outlines of 2D Point Sets and Holes using Dominant Directions or Orthogonal Projections

Authors:

Melanie Pohl and Dirk Feldmann

Abstract: Representing the shape of finite point sets in 2D by simple polygons becomes a challenge if the resulting outline needs to be non-convex and straight with only few, distinct edges and angles. Such outlines are usually sought in order to border point sets that originate from man-made objects, e.g., for the purpose of building reconstruction from LIDAR data. Algorithms for computing hulls of point sets obtained from such structures usually yield polygons having too many edges and angles and may thus not capture the actual shape very well. Furthermore, many existing approaches cannot handle empty domains within the boundaries of a point set (holes). In this paper, we present methods that create straight, non-convex outlines of finite 2D point sets and of possibly contained holes. The resulting polygons feature fewer vertices and angles than hulls and can thus faithfully represent objects of angular shapes.

Short Papers
Paper Nr: 1
Title:

Hessian Eigenfunctions for Triangular Mesh Parameterization

Authors:

Daniel Mejia, Oscar Ruiz-Salguero and Carlos A. Cadavid

Abstract: Hessian Locally Linear Embedding (HLLE) is an algorithm that computes the nullspace of a Hessian functional H for Dimensionality Reduction (DR) of a sampled manifold M. This article presents a variation of classic HLLE for parameterization of 3D triangular meshes. Contrary to classic HLLE which estimates local Hessian nullspaces, the proposed approach follows intuitive ideas from Differential Geometry where the local Hessian is estimated by quadratic interpolation and a partition of unity is used to join all neighborhoods. In addition, local average triangle normals are used to estimate the tangent plane TxM at x 2 M instead of PCA, resulting in local parameterizations which reflect better the geometry of the surface and perform better when the mesh presents sharp features. A high frequency dataset (Brain) is used to test our algorithm resulting in a higher rate of success (96:63%) compared to classic HLLE (76:4%).

Paper Nr: 7
Title:

An External Memory Algorithm for the Minimum Enclosing Ball Problem

Authors:

Linus Källberg, Evan Shellshear and Thomas Larsson

Abstract: In this article we present an external memory algorithm for computing the exact minimum enclosing ball of a massive set of points in any dimension. We test the performance of the algorithm on real-life three-dimensional data sets and demonstrate for the first time the practical efficiency of exact out-of-core algorithms. By use of simple heuristics, we achieve near-optimal I/O in all our test cases.

Paper Nr: 42
Title:

Geometric Approach to Estimation of Volumetric Distortions

Authors:

Alexander Naitsat, Emil Saucan and Yehoshua Y. Zeevi

Abstract: The problem of measuring geometrical distortions is not trivial for volumetric domains. There exist intrinsic restrictions and constrains on higher dimensional mappings. Moreover, according to Liouville theorem, most existing techniques for 2D data can not be directly applied to volumetric objects. In this work we approximate continuous deformations by piecewise affine functions defined on tetrahedral meshes. Our aim is to study a few types of geometrical distortions that can be expressed as functions of singular values of a Jacobian. We employ the proposed methods of estimating conformal and isometric distortions to analyze volumetric data. In particular, we examine parametrization of tetrahedral models to a ball. Distortions produced by the resulting spatial mappings depict intrinsic structure of domains, and therefore can be employed in such tasks as detection of abnormalities and comparison (i.e. similarity assessment) between 3D objects. This geometric approach and results are highly relevant to various applications in Computer Vision, Computer Graphics, 3D Printing and Medical Imaging.

Paper Nr: 46
Title:

Customized 3D Clothes Modeling for Virtual Try-on System based on Multiple Kinects

Authors:

Shiyi Huang and Won-sook Lee

Abstract: Most existing 3D virtual try-on systems put clothes designed in one environment on a human captured in another environment, which cause the mismatching brightness problem. And also typical 3D clothes modeling starts with manually designed 2D patterns, deforms them to fit on a human, and applies stitching to sew those patterns together. Such work usually relies on labour work. In this paper, we describe an approach to reconstruct clothes and human that both are from the same space. With multiple Kinects, it models the 3D clothes directly out of a dressed human without the need of the predefined 2D clothes patterns, and fits them to a human user. Our approach has several advantages: (1) a simple hardware setting consisted of multiple Kinects to capture a human model; (2) 3D clothes modeling directly out of captured human model. To the best of our knowledge, our work is the first one which separates clothes out of captured human figures; (3) resizing of clothes adapting to any sized human user; (4) a novel idea of virtual try-on where clothes and human are captured in the same location.

Posters
Paper Nr: 18
Title:

3D Geometric Primitive Alignment Revisited

Authors:

Trung-Thien Tran, Van-Toan Cao and Denis Laurendeau

Abstract: Rigid registration is an important step in 3D scanning and modeling of manufactured objects that are generally composed of a combination of basic geometric primitives such as planes, spheres, cylinders, etc. In this paper, an efficient and robust method is proposed to align two basic geometric primitives. The transformation between two primitives is found by minimizing the parameter error between primitive correspondences. The approach applies an interior-point method and a new objective function to achieve good results. Compared to previous primitive-based alignment approach proposed by Rabbani et al. (Rabbani et al., 2007), the presented approach achieves better results in terms of convergence and accuracy. Finally, the proposed method is used in various applications such as data completion and primitive-based registration for quality control and inspection.

Paper Nr: 37
Title:

A Digital Hand to Mimic Human Hand in Real Time Operation - Making of Digital Finger with Partial Soft Skin and Rigid Bone

Authors:

Hiroshi Hashimoto, Sho Yokota, Daisuke Chugo and Kaoru Mitsuhashi

Abstract: This paper presents a digital hand which is a type of model to mimic human hand operation in real time operation. Human hand performs various difficult tasks in daily life and shows dexterous operation to use tools or equipment, because it has numerous degree of freedom (DoFs) of finger joints and soft skin. To realize the mimic of human hand operation in real time operation to overcome the problems such as high DoFs, soft skin. We have developed the digital hand whose input to control hand posture is obtained from a hand posture sensor and soft skin is designed as mesh structure. Here, the way to define parameters of mesh structure is discussed. We demonstrate the simulation of the digital hand model and examine how the model is able to mimic the motion of human hand.

Paper Nr: 44
Title:

Computational Methods for the Animation of Heat Transfer Evolution and Steel Solidification

Authors:

Adán Ramírez-López, David F. Muñoz, Sergio Romero-Hernández and Simón López-Ramírez

Abstract: This work shows the use of some basic animation techniques to develop a computer simulator capable to display the heat transfer of steel during a continuous casting process. This is the most popular method to produce steel in big bulks. Nevertheless, continuous casting involves the interaction of complex heat transfer phenomena such as conduction, radiation and forced convection, and appropriate algorithms with graphical tools must be developed to display thermal and solidification profiles according to temperature values. Here a 2D model was applied for calculation purposes; nevertheless the animation techniques employed allowed us to display a 3D representation. Furthermore, additional enhancements were created to show the internal thermal behaviour. A math model provided a good approach for process simulation and the animation procedures were successfully tested to provide a good visual display.

Paper Nr: 48
Title:

Resolution-aware Slicing of CAD Data for 3D

Authors:

Isidore Onyeako and Won-sook Lee

Abstract: Low resolution printing results in fused joints when the joint clearance is intended to be very small. Various 3D printers are capable of print resolutions of up to 600dpi (dots per inch) as quoted in their datasheets. It is imperative to include the ability of a 3D slicing application, to validate 3D models, based on the ability of the printer to properly produce the features with the smallest detail in a model. A way to perform this validation would be the physical measurement of printed parts and comparison to expected results. Our method uses ray casting to detect features in the 3D models whose sizes are below the minimum allowed by the printer resolution. Our model was tested using few simple and complex 3D models. Areas in the slices with thickness less than the specified resolution were detected. Our model serves two purposes: (a) to assist CAD model designers in developing models whose printability is assured- by warning or preventing shape operations that will lead to regions/features with sizes lower than that of the printer resolution; (b) to validate slicing outputs to identify regions/features with sizes lower than the printer resolution. This makes our model very powerful in the quality assurance of 3D printing and a huge cost/time saver when planning for 3D printing.

Paper Nr: 51
Title:

Camarón: An Open-source Visualization Tool for the Quality Inspection of Polygonal and Polyhedral Meshes

Authors:

Aldo Canepa, Gonzalo Infante, Nancy Hitschfeld and Claudio Lobos

Abstract: The numerical simulation of phenomena requires a good quality discretization (mesh) of the domain. Depending on the problem to be simulated, the mesh has to fulfil different quality criteria. Because of geometry restrictions or point density requirements, several mesh elements might not satisfy the required quality criteria and sometimes it is also not required that all elements fulfil them. Then, it would be helpful to know where unwanted elements are located in order to see if they need to be repaired or not. That is why a visualization tool that allows the user to inspect a mesh before a simulation is performed can be useful to prevent simulation problems. Moreover, if data from simulations is available, the visualization of geometrical properties together with simulation data could be also helpful to understand not expected results. These challenges have motivated us to develop Camar´on, a visualization tool for large surface and volume meshes described in this paper. The surface meshes can be composed any polygonal cell and the 3D meshes can include any convex polyhedral cell. This tool was implemented in C++ and the OpenGL Shading Language (GLSL). We discuss the design and implementation issues that make our software portable, extensible and different from other visualization tools. We also compare the performance between Camar´on and GeomView, TetView and MeshLab.

Area 2 - Rendering

Full Papers
Paper Nr: 2
Title:

Real-time Image Vectorization on GPU

Authors:

Xiaoliang Xiong, Jie Feng and Bingfeng Zhou

Abstract: In this paper, we present a novel algorithm to convert a raster image into its vector form. Different from the state-of-art methods, we explore the potential parallelism that exists in the problem and propose an algorithm suitable to be accelerated by the graphics hardware. In our algorithm, the vectorization task is decomposed into four steps: detecting the boundary pixels, pre-computing the connectivity relationship of detected pixels, organizing detected pixels into boundary loops and vectorizing each loop into line segments. The boundary detection and connectivity pre-computing are parallelized owing to the independence between scanlines. After a sequential boundary pixels organizing, all loops are vectorized concurrently. With a GPU implementation, the vectorization can be accomplished in real-time. Then, the image can be represented by the vectorized contour. This real-time vectorization algorithm can be used on images with multiple silhouettes and multi-view videos. We demonstrate the efficiency of our algorithm with several applications including cartoon and document vectorization.

Paper Nr: 8
Title:

Fast Screen Space Curvature Estimation on GPU

Authors:

Martin Prantl, Libor Váša and Ivana Kolingerová

Abstract: Curvature is an important geometric property in computer graphics that provides information about the behavior of object surfaces. The exact curvature can only be calculated for a limited set of surfaces description. Most of the time, we deal with triangles, point sets or some other discrete representation of the surface. For those, curvature computation is problematic. Moreover, most of existing algorithms were developed for static geometry and can be slow for interactive modeling. This paper proposes a screen space method which estimates the mean and Gaussian curvature at interactive rates. The algorithm uses positions and normals to estimate the curvature from the second fundamental form matrix. Using the screen space has advantages over the classical approach: low-poly geometry can be used and additional detail can be added with normal and bump maps. The screen space curvature can be easily added to existing rendering pipelines. The proposed algorithm was tested on several models and it outperforms current state-of-the-art GPU approaches.

Posters
Paper Nr: 11
Title:

Shader Programming for Computational Arts and Design - A Comparison between Creative Coding Frameworks

Authors:

Andrés Felipe Gómez, Andrés Colubri and Jean Pierre Charalambos

Abstract: We describe an Application Program Interface (API) that facilitates the use of GLSL shaders in computational design, interactive arts, and data visualization. This API was first introduced in the version 2.0 of Processing, a programming language and environment widely used for teaching and production in the context of media arts and design, and has been recently completed in the 3.0 release. It aims to incorporate low-level shading programming into code-based design, by integrating traditional models of graphics programming with more expressive approaches afforded by the OpenGL pipeline on modern GPUs. We contrast Processing's shader API with similar interfaces available in other frameworks used in computational arts and design, in order to better understand its advantages and shortcomings.

Paper Nr: 34
Title:

Half-precision Floating-point Ray Traversal

Authors:

Matias Koskela, Timo Viitanen, Pekka Jääskeläinen and Jarmo Takala

Abstract: Ray tracing is a memory-intensive application. This paper presents a new ray traversal algorithm for bounding volume hierarchies. The algorithm reduces the required memory bandwidth and energy usage, but requires extra computations. This is achieved with a new kind of utilization of half-precision floating-point numbers, which are used to store axis aligned bounding boxes in a hierarchical manner. In the traversal the ray origin is moved to the edges of the intersected nodes. Additionally, in order to retain high accuracy for the intersection tests the moved ray origin is converted to the child’s hierarchical coordinates, instead of converting the child’s bound coordinates into world coordinates. This means that both storage and the ray intersection tests with axis aligned bounding boxes can be done in half-precision. The algorithm has better results with wider vector instructions. The measurements show that on a Mali-T628 GPU the algorithm increases frame rate by 3% and decreases power consumption by 9% when wide vector instructions are used.

Paper Nr: 41
Title:

Occluding Edges Soft Shadows - A New Approach for Realistic Shadows using Occluding Edges

Authors:

Christian Liwai Reimann and Bernd Dreier

Abstract: In this paper, a new algorithm to render soft shadows in real time applications is introduced, namely the Occluding Edges Soft Shadow algorithm (short OESS). The algorithm approximates the shadow cast from linear lights by finding the outlines of an occluding object (Occluding Edges) and considering these in a fragment’s illumination. The method is based on the shadow mapping technique, whereby its capability of rendering the shadow at an interactive rate does not depend on the complexity of the scene. The paper supplies an overview for several methods to produce shadows and soft shadows in real time computer graphics, a detailed description of the newly developed algorithm, and a section with results and future possibilities for improvements.

Area 3 - Animation and Simulation

Full Papers
Paper Nr: 3
Title:

TraceMove: A Data-assisted Interface for Sketching 2D Character Animation

Authors:

Priyanka Patel, Heena Gupta and Parag Chaudhuri

Abstract: In this paper we present TraceMove, a system to help novice animators create 2D, hand-drawn, character animation. The system and interface assists not only in sketching the character properly but also in animating it. A database of image frames, from recorded videos of humans performing various motions, is used to provide pose silhouette suggestions as a static pose hint to the users as they draw the character. The user can trace and draw over the generated suggestions to create the sketch of the pose. Then the sketch of the next frame of the animation being drawn is automatically generated by the system as a moving pose hint. In order to do this, the user marks the skeleton of the character in a single sketched pose, and a motion capture database is used to predict the skeleton for the subsequent frame. The sketched pose is then deformed according to the predicted skeleton pose. Furthermore, the sketch generated by the system for any frame can always be edited by the animator. This lets novice artists and animators generate hand-drawn 2D animated characters with minimal effort.

Paper Nr: 24
Title:

State of the Art in Skinning Techniques for Articulated Deformable Characters

Authors:

Nadine Abu Rumman and Marco Fratarcangeli

Abstract: Skinning is an indispensable component of the content creation pipeline for character animation in the context of feature films, video games, and in the special effects industry. Skinning techniques define the deformation of the character skin for every animation frame according to the current state of skeletal joints. In this state of the art report, we focus on the existing research in the areas of skeleton-based deformation, volume preserving techniques and physically based skinning methods. We also summarize the recent research in deformable and soft bodies simulations for articulated characters, and discuss various geometric and examples-based approaches.

Short Papers
Paper Nr: 36
Title:

Interactive Control of Fire Simulation based on Computational Fluid Dynamics

Authors:

Keisuke Mizutani, Yoshinori Dobashi and Tsuyoshi Yamamoto

Abstract: Visual simulation of fire plays an important role in many applications, such as movies and computer games. In these applications, artists are often requested to synthesize realistic fire with a particular behavior. This paper presents two methods in order to help artists meet such requirements. First, we propose a method for controlling fire simulation by extending a previous method for smoke simulation. Controlling fire simulation with the previous method is difficult because of strong buoyancy forces caused by high-temperature. To address this problem, our method locally adjusts magnitudes of control forces. Second, we present an interactive editing method for external force field. The user can interactively design the shape of fire by placing a set of control points. Our method generates a force field to form the shape of the fire. Experimental results show that our method can control the fire into an arbitrary shape specified by the user.

Posters
Paper Nr: 5
Title:

Fluid Simulation by the Smoothed Particle Hydrodynamics Method: A Survey

Authors:

T. Weaver and Z. Xiao

Abstract: This paper presents a survey of Smoothed Particle Hydrodynamics (SPH) and its use in computational fluid dynamics. As a truly mesh-free particle method based upon the Lagrangian formulation, SPH has been applied to a variety of different areas in science, computer graphics and engineering. It has been established as a popular technique for fluid based simulations, and has been extended to successfully simulate various phenomena such as multi-phase flows, rigid and elastic solids, and fluid features such as air bubbles and foam. Various aspects of the method will be discussed: Similarities, advantages and disadvantages in comparison to Eulerian methods; Fundamentals of the SPH method; The use of SPH in fluid simulation; The current trends in SPH. The paper ends with some concluding remarks about the use of SPH in fluid simulations, including some of the more apparent problems, and a discussion on prospects for future work.

Paper Nr: 20
Title:

Low Bandwidth Video Streaming using FACS, Facial Expression and Animation Techniques

Authors:

Dinesh Kumar and Jito Vanualailai

Abstract: In this paper we describe an easy to use real-time 3D facial expression and animation system that takes the creation of individual facial expressions to the atomic level. That is instead of generating and recording known facial expressions we propose a mechanism that will allow us to create and store each atomic facial distortion. We can then combine some of these singular distortions to create meaningful expressions. FACS Action Units (AUs) is one such technique that describes the simplest visible movement, which cannot be decomposed into more basic ones. We use this as the basis for creating these atomic facial distortions. The Waters muscle based facial model has been used and extended to allow the user to calibrate and record each facial deformation as described in FACS AUs. The user can then create any facial expression by simply stating the series of AUs and its degree of activation in a controlled fashion. These features all form part of the Facial Animation System (FAS). Our FAS is implemented in such a way that enables it to be used as a low bandwidth video streaming player - a real time facial animation player driven only by FACS AUs transmitted as plain text over TCP sockets.

Paper Nr: 35
Title:

Creating Endless Water Flow Animation using Particle Data

Authors:

Masanori Sotozaki, Yoshinori Dobashi and Tsuyoshi Yamamoto

Abstract: In this paper, we propose an efficient method for synthesizing water animation such as waterfall or rivers using particle-based simulation. Recently, physically based simulation has become a popular technique to create realistic animation of natural phenomena in many applications, e.g. commercial films, movies and games. Particularly, there is a growing demand on synthesizing realistic animation of fluids, such as water. However, realistic fluid animation requires a high computational cost. Some applications requiring real time performances, such as games, cannot afford such a high computational cost. In this paper, we propose an efficient method for creating endless animations of water flow using particle data generated by fluid simulation. We store a set of dynamic particles in a database and use them repeatedly to produce endless animations.

Paper Nr: 38
Title:

Particle-based Simulation on Aortic Valve Behavior with CG Model Generated from CT

Authors:

Nobuhiko Mukai, Tomofumi Takahashi and Youngha Chang

Abstract: We have tried to simulate the aortic valve behavior with a particle method. The simulation model has been generated from CT data; however, the model was a little bit distorted due to some diseases. The distorted model is not appropriate for the simulation because we have to simulate the aortic valve behavior for various kinds of conditions. Then, we have created the normal model by modifying the generated model. In order to simulate the aortic valve behavior, blood should be flown in the aortic model and particle methods are suitable for fluid simulation. On the other hand, FEM (Finite Element Method) is usually used for the simulation of elastic body such as the aortic wall and the aortic valve. However, it is difficult to calculate the mutual interaction between fluid and elastic body if two different kinds of methods such as particle method and FEM are adopted for one simulation. Therefore, we have applied a particle method for both of fluid and elastic body. As the result of the simulation, we have been able to visualize the blood flow and the pressure inside the aorta, and the stress distribution on the aortic valve.

Area 4 - Interactive Environments

Full Papers
Paper Nr: 6
Title:

Highlighting Techniques for Real Entities in Augmented Reality

Authors:

Sebastian Fuchs, Mario Sigel and Ralf Dörner

Abstract: One fundamental task in Augmented Reality is to highlight specific real world entities or small areas in the user‘s view. For this purpose, a total of 9 novel highlighting techniques were designed and implemented. For comparison, they are complemented by two conventional techniques often used in practice. This paper presents the techniques and evaluates them based on a user study in which 23 participants were asked questions concerning the degree of attention as well as disturbances caused by the highlighting techniques. The user study revealed that particle systems are a successful tool to effectively draw attention to a highlighted entity without causing annoying distractions.

Paper Nr: 31
Title:

3D Interaction Techniques for Virtual Shopping: Design and Preliminary Study

Authors:

Eulalie Verhulst, Paul Richard, Emmmanuelle Richard, Philippe Allain and Pierre Nolin

Abstract: Virtual Reality is now recognized as a powerful tool for the assessment and rehabilitation of both motor and cognitive impairments. In this context, effective Virtual Environments (VEs) that simulate everyday tasks must be proposed. We have developed a virtual supermarket (VS) in which the user can explore and collect various items using a shopping cart. Four interaction techniques have been designed and compared in terms of usability, performance and workload with healthy volunteer participants. These techniques go beyond the desktop paradigm by offering a more immersive and intuitive way of interaction. Results showed that participants were more efficient in terms of performance (completion time and travelled distance) using the game-pad rather than using full body gestures. However, they had more fun performing the task under these conditions.

Short Papers
Paper Nr: 30
Title:

Assessing 3D Geovisualization for the Communication of Public Art

Authors:

Vincenzo Lombardo and Rossana Damiano

Abstract: This paper presents the assessment of a 3D geovisualization framework and system for the documentation and communication of contemporary public art. The paper reviews the specific requirements of the contemporary public art and discusses the critical issues connected to the visualization of such artworks. The framework implements a visualization pipeline that relies on both a semantic representation of the artworks and a mixture of graphic elements acquired from reality or designed for the application. The web-based visualization system realizes a geolocalized 3D layout that selects the relevant traits that characterize the contemporary public artworks. The system is implemented in a prototype applied to the visualization of contemporary public artworks of the municipality of Turin (Italy). The assessment is achieved through the evaluation of a number of typical tasks that general audiences engage with contemporary public art, the system has revealed to be more adequate to its design goals.

Posters
Paper Nr: 15
Title:

Building a Driving Simulator with Parallax Barrier Displays

Authors:

Christoph Schinko, Markus Peer, Daniel Hammer, Matthias Pirstinger, Cornelia Lex, Ioana Koglbauer, Arno Eichberger, Jürgen Holzinger, Eva Eggeling, Dieter W. Fellner and Torsten Ullrich

Abstract: In this paper, we present an optimized 3D stereoscopic display based on parallax barriers for a driving simulator. The overall purpose of the simulator is to enable user studies in a reproducible environment under controlled conditions to test and evaluate advanced driver assistance systems. Our contribution and the focus of this article is a visualization based on parallax barriers with (I) a-priori optimized barrier patterns and (II) an iterative calibration algorithm to further reduce visualization errors introduced by production inaccuracies. The result is an optimized 3D stereoscopic display perfectly integrated into its environment such that a single user in the simulator environment sees a stereoscopic image without having to wear specialized eye-wear.

Paper Nr: 17
Title:

Inside - Outside Model Viewing - A Low-cost Hybrid Approach to Visualization and Demonstration of 3D Models

Authors:

Ivan A. Nikolov

Abstract: Visualization of large scale 3D models has become an important part of the development cycle in many fields like building design, machine design, construction and many more. Whether for design communication or demonstration, it is necessary for the viewers to fully understand the different components of the model, their proportions compared to each other and the overall design. A variety of augmented reality(AR) applications have been created for overall visualization of large scale models. For tours inside 3D renderings of models many immersive virtual reality (VR) applications exist. Both types of applications have their limitation, omitting either important details in the AR case or the full picture in the case of VR. This paper presents a low-cost way to demonstrate models using a hybrid virtual environment system (HVE), combining virtual reality and augmented reality visualization. The solution is built using a fully occlusive head mounted display(HMD), together with off-the-shelf web cameras and a game controller for interaction. A proof of concept is created using a commercial game engine, which is used in a subsequent case study. Based on this study, we demonstrate the validity of our proposed system.

Paper Nr: 23
Title:

Virtual Humans Playing the Role of Patients in Self-medication Consultations: Perspectives of Undergraduate Pharmacy Students

Authors:

Ana Paula Cláudio, Maria Beatriz Carmo, Mara Pereira Guerreiro, Afonso Cavaco, Vítor Pinto and Ana Pinha

Abstract: This paper describes an interactive application conceived to improve non-prescription medicines consultation skills in undergraduate Pharmacy students and a user test carried out with two sets of participants. Resorting to virtual humans that play the role of patients and communicate with the students by speech and by facial and body language, the application stimulates students’ engagement in true to life situations in a controllable environment. Two usage modes are available: the training mode, used autonomously by the student, and the assessment mode which is used by the teacher to evaluate the student’s performance. A BackOffice Web application was also implemented to assist teachers’ work. It supports the collection of data about students’ performance, the creation of new self medication situations and their posterior insertion in the application. The overall opinion of the participants in the user-study was quite positive about the usefulness of the application as a tool to improve students’ non-prescription medicines consultation skills. Moreover, some valuable suggestions were gathered during this testing process.

Paper Nr: 27
Title:

Virtual Reality System for Rehabilitation of Children with Cerebral Palsy: A Preliminary Study

Authors:

Pierre Michel, Paul Richard, Takehiko Yamaguchi, Adrien Verhulst, Eulalie Verhulst and Mickaël Dinomais

Abstract: We present a non-immersive virtual reality (VR) system for the rehabilitation of children with Cerebral Palsy (CP). Our objective is to encourage and motivate children to improve their limb motor control while play- ing a game. Two tasks are available : (1) intercepting or (2) to catching / releasing moving objects using a Kinect sensor. These tasks are achieved via the control of a virtual character placed in a virtual island. A control-display ratio is used to virtually increase the child workspace allowing him/her to reach all the approaching objects. In addition, a dynamic difficulty adjustment (DDA) is used to keep a good motivation level. Furthermore, a virtual coach is provided to support and congratulate the children. Twenty healthy chil- dren participated in a preliminary experiment. The aim was (1) to collect control data concerning performance and workload, and (2) to investigate the effect of the virtual coach. Results show a good usability of the game and reveal a high ratio of acceptance and enjoyment from the children.

Paper Nr: 33
Title:

Extensible Immersive Virtual Environments for Large Tiled Video Walls

Authors:

Lorenz Cuno Klopfenstein, Brendan D. Paolini, Gioele Luchetti and Alessandro Bogliolo

Abstract: The intent of the work is to present an Immersive Virtual Environment (IVE) as a new abstracted management layer on top of the Scalable Adaptive Graphics Environment (SAGE) system, allowing the simplified management and linear scaling of multiple SAGE-driven video walls, and the creation and control of simple interactive scenarios. The framework exposes evolved Application Programming Interfaces (APIs) that are detached from the underlying system and can be used by mobile clients as well. Primitives offered to developers and content creators allow the definition of immersive cinematographic experiences using basic commands, which are synchronized on the whole IVE environment. A complete implementation of the system is described and then evaluated with the specific case of one physical installation.

Area 5 - Social Agents in Computer Graphics

Full Papers
Paper Nr: 13
Title:

Appealing Female Avatars from 3D Body Scans: Perceptual Effects of Stylization

Authors:

Reuben Fleming, Betty J. Mohler, Javier Romero, Michael J. Black and Martin Breidt

Abstract: Advances in 3D scanning technology allow us to create realistic virtual avatars from full body 3D scan data. However, negative reactions to some realistic computer generated humans suggest that this approach might not always provide the most appealing results. Using styles derived from existing popular character designs, we present a novel automatic stylization technique for body shape and colour information based on a statistical 3D model of human bodies. We investigate whether such stylized body shapes result in increased perceived appeal with two different experiments: One focuses on body shape alone, the other investigates the additional role of surface colour and lighting. Our results consistently show that the most appealing avatar is a partially stylized one. Importantly, avatars with high stylization or no stylization at all were rated to have the least appeal. The inclusion of colour information and improvements to render quality had no significant effect on the overall perceived appeal of the avatars, and we observe that the body shape primarily drives the change in appeal ratings. For body scans with colour information, we found that a partially stylized avatar was most effective, increasing average appeal ratings by approximately 34%.