EG2018

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https://diglib.eg.org/handle/10.2312/2632158

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Accelerating Sphere Tracing
(The Eurographics Association, 2018) Bálint, Csaba; Valasek, Gábor; Diamanti, Olga and Vaxman, Amir
This paper presents two performance improvements on sphere tracing. First, a sphere tracing variant designed to take optimal step sizes near planar surfaces is proposed. We demonstrate how relaxation is used to make this method applicable to sphere tracing arbitrary geometries and compare its performance to classical (by Hart) and relaxed (Keinert et al.) sphere tracing in rendering various scenes. The method is also general in the sense that it can be applied in any scenario that requires the computation of ray-surface intersections. Our second contribution is a multi-resolution rendering strategy that can be used with any sphere tracing variant. By starting from a lower resolution and gradually increasing it, render times can be reduced.
Accurate Control of a Pan-tilt System Based on Parameterization of Rotational Motion
(The Eurographics Association, 2018) Byun, JungHyun; Chae, SeungHo; Han, TackDon; Diamanti, Olga and Vaxman, Amir
A pan-tilt camera system has been adopted by a variety of fields since it can cover a wide range of region compared to a single fixated camera setup. Yet many studies rely on factory-assembled and calibrated platforms and assume an ideal rotation where rotation axes are perfectly aligned with the optical axis of the local camera. However, in a user-created setup where a pan-tilting mechanism is arbitrarily assembled, the kinematic configurations may be inaccurate or unknown, violating ideal rotation. These discrepancies in the model with the real physics result in erroneous servo manipulation of the pan-tilting system. In this paper, we propose an accurate control mechanism for arbitrarily-assembled pan-tilt camera systems. The proposed method formulates pan-tilt rotations as motion along great circle trajectories and calibrates its model parameters, such as positions and vectors of rotation axes, in 3D space. Then, one can accurately servo pan-tilt rotations with pose estimation from inverse kinematics of their transformation. The comparative experiment demonstrates out-performance of the proposed method, in terms of accurately localizing target points in world coordinates, after being rotated from their captured camera frames.
Arm Swinging vs Treadmill: A Comparison Between Two Techniques for Locomotion in Virtual Reality
(The Eurographics Association, 2018) Calandra, Davide; Billi, Michele; Lamberti, Fabrizio; Sanna, Andrea; Borchiellini, Romano; Diamanti, Olga and Vaxman, Amir
When it comes to locomotion in Virtual Reality (VR), a wide range of different techniques has been proposed in the scientific literature or as commercial products. However, the best choice for a specific application is still not immediate, being each technique characterized by different advantages and drawbacks. The present work reports on the results of a user study-based comparison between two methods: a locomotion treadmill, which supports omni-directional movements through walking in place over a hardware device, and Arm Swinging, which recognizes movement from the swinging back and forth of the user's arms (e.g., gathered by sensors embedded in hand controllers). Experiments have been carried out in a realistic immersive VR scenario, which requested users to respond to a fire emergency in a road tunnel by moving and interacting with the environment.
Audio-driven Emotional Speech Animation
(The Eurographics Association, 2018) Charalambous, Constantinos; Yumak, Zerrin; Stappen, A. Frank van der; Jain, Eakta and Kosinka, Jirí
We propose a procedural audio-driven speech animation method that takes into account emotional variations in speech. Given any audio with its corresponding speech transcript, the method generates speech animation for any 3D character. The expressive speech model matches the pitch and intensity variations in audio to individual visemes. In addition, we introduce a dynamic co-articulation model that takes into account linguistic rules varying among emotions. We test our approach against two popular speech animation tools and we show that our method surpass them in a perceptual experiment.
Boundary-aided Human Body Shape and Pose Estimation from a Single Image for Garment Design and Manufacture
(The Eurographics Association, 2018) Xu, Zongyi; Zhang, Qianni; Jain, Eakta and Kosinka, Jirí
Current virtual clothing design applications mainly use predefined virtual avatars which are created by professionals. The models are unrealistic as they lack the personalised body shapes and the simulation of human body muscle and soft tissue. To address this problem, we firstly fit the state-of-the-art parametric 3D human body model, SMPL, to 2D joints and boundary of the human body which are detected using CNN methods automatically. Considering the scenario of virtual dressing where people are usually in stable poses, we define a stable pose prior from CMU motion capture (mocap) dataset for further improving accuracy of pose estimation. Accurate estimation of human body shape and poses provides manufacturers and designers with more comprehensive human body measurements, which put a step forwards clothing design and manufacture through Internet.
A Comparison of GPU Tessellation Strategies for Multisided Patches
(The Eurographics Association, 2018) Hettinga, Gerben Jan; Barendrecht, Pieter J.; Kosinka, Jiri; Diamanti, Olga and Vaxman, Amir
We propose an augmentation of the traditional tessellation pipeline with several different strategies that efficiently render multisided patches using generalised barycentric coordinates. The strategies involve different subdivision steps and the usage of textures. In addition, we show that adaptive tessellation techniques naturally extend to some of these strategies whereas others need a slight adjustment. The technique of Loop et al. [LSNC09], commonly known as ACC-2, is extended to multisided faces to illustrate the effectiveness of multisided techniques. A performance and quality comparison is made between the different strategies and remarks on the techniques and implementation details are provided.
Creating New Chinese Fonts based on Manifold Learning and Adversarial Networks
(The Eurographics Association, 2018) Guo, Yuan; Lian, Zhouhui; Tang, Yingmin; Xiao, Jianguo; Diamanti, Olga and Vaxman, Amir
The design of fonts, especially Chinese fonts, is known as a tough task that requires considerable time and professional skills. In this paper, we propose a method to easily generate Chinese font libraries in new styles based on manifold learning and adversarial networks. Starting from a number of existing fonts that cover various styles, we firstly use convolutional neural networks to obtain the representation features of these fonts, and then build a font manifold via non-linear mapping. Using the font manifold, we can interpolate and move between those existing fonts to get new font features, which are then fed into a generative network learned via adversarial training to generate the whole new font libraries. Experimental results demonstrate that high-quality Chinese fonts in various new styles against existing ones can be efficiently generated using our method.
A Creative First Assignment in the Modern Graphics Pipeline
(The Eurographics Association, 2018) Fourquet, Elodie; Pentecost, Lillian; Post, Frits and Žára, Jirí
This paper describes a first assignment in an Introduction to Computer Graphics course taken by undergraduate students at a liberal arts college. The assignment marries the technical challenges found at the lowest level of the modern graphics pipeline with the artistic concerns of reproducing a piece of art. To do so, students extend provided code in WebGL, which includes GLSL shaders and no additional libraries, to reproduce a work of art of their own choosing. This task requires the students to involve themselves simultaneously in the most technical and most artistic aspects of computer graphics. Such an inter-disciplinary approach helps to reach a more diverse audience of computer graphics learners.
Deep Learning for Graphics
(The Eurographics Association, 2018) Mitra, Niloy J.; Ritschel, Tobias; Kokkinos, Iasonas; Guerrero, Paul; Kim, Vladimir; Rematas, Konstantinos; Yumer, Ersin; Ritschel, Tobias and Telea, Alexandru
In computer graphics, many traditional problems are now better handled by deep-learning based data-driven methods. In applications that operate on regular 2D domains, like image processing and computational photography, deep networks are state-of-the-art, beating dedicated hand-crafted methods by significant margins. More recently, other domains such as geometry processing, animation, video processing, and physical simulations have benefited from deep learning methods as well. The massive volume of research that has emerged in just a few years is often difficult to grasp for researchers new to this area. This tutorial gives an organized overview of core theory, practice, and graphics-related applications of deep learning.
A Drink in Mars: an Approach to Distributed Reality
(The Eurographics Association, 2018) Perez, Pablo; Gonzalez-Sosa, Ester; Kachach, Redouane; Ruiz, Jaime Jesus; Villegas, Alvaro; Jain, Eakta and Kosinka, Jirí
We have developed A Drink in Mars application as a proof of concept of Distributed Reality, a particularisation of Mixed Reality which combines a reality transmitted from a remote place (e.g. live immersive video stream from Mars) with user interaction with the local reality (e.g. drink their favourite beverage). The application shows acceptable immersion and local interactivity. It runs on Samsung GearVR and needs no special green room for chroma keying, thus being suitable to test different use cases.
EUROGRAPHICS 2018: CGF 37-2 STARs Frontmatter
(The Eurographics Association and John Wiley & Sons Ltd., 2018) Hildebrandt, Klaus; Theobalt, Christian; Hildebrandt, Klaus; Theobalt, Christian
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EUROGRAPHICS 2018: Education Papers Frontmatter
(Eurographics Association, 2018) Post, Frits; Žára, Jirí; Post, Frits; Žára, Jirí
EUROGRAPHICS 2018: Posters Frontmatter
(Eurographics Association, 2018) Jain, Eakta; Kosinka, Jirí; Jain, Eakta; Kosinka, Jirí
EUROGRAPHICS 2018: Short Papers Frontmatter
(Eurographics Association, 2018) Diamanti, Olga; Vaxman, Amir; Diamanti, Olga; Vaxman, Amir
EUROGRAPHICS 2018: Tutorials Frontmatter
(Eurographics Association, 2018) Ritschel, Tobias; Telea, Alexandru; Ritschel, Tobias; Telea, Alexandru
Exemplar Based Filtering of 2.5D Meshes of Faces
(The Eurographics Association, 2018) Dihl, Leandro; Cruz, Leandro; Gonçalves, Nuno; Jain, Eakta and Kosinka, Jirí
In this work, we present a content-aware filtering for 2.5D meshes of faces. We propose an exemplar-based filter that corrects each point of a given mesh through local model-exemplar neighborhood comparison. We take advantage of prior knowledge of the models (faces) to improve the comparison. We first detect facial feature points, and create the point correctors for regions of each feature, and only use the correspondent regions for correcting a point of the filtered mesh.
Expressive Curve Editing with the Sigma Lognormal Model
(The Eurographics Association, 2018) Berio, Daniel; Leymarie, Frederic Fol; Plamondon, Réjean; Diamanti, Olga and Vaxman, Amir
We describe a practical application of the Sigma Lognormal model of handwriting movements for computer graphics applications that require the interactive or procedural definition of artistic or calligraphic traces. The method allows to easily edit curves with physiologically plausible kinematics that can be exploited in order to generate expressive brush renderings, natural looking stroke animations and easily generate stylistic variations of a trace.
From Spectra to Perceptual Color: Visualization Tools for the Dimensional Reduction Achieved by the Human Color Sense
(The Eurographics Association, 2018) Harvey, Joshua S.; Siviour, Clive R.; Smithson, Hannah E.; Jain, Eakta and Kosinka, Jirí
Physical colors, defined as unique combinations of photon populations whose wavelengths lie in the visible range, occupy an infinite-dimensional real Hilbert space. Any number of photon populations from the continuous spectrum of monochromatic wavelengths may be present to any positive amount. For normal vision, this space collapses to three dimensions at the retina, with any physical color eliciting just three sensor values corresponding to the excitations of the three classes of cone photoreceptor cells. While there are many mappings and visualizations of three-dimensional perceptual color space, attempts to visualize the relationship between infinite-dimensional physical color space and perceptual space are lacking. We present a visualization framework to illustrate this mathematical relation, using animation and transparency to map multiple physical colors to locations in perceptual space, revealing how the perceptual color solid can be understood as intersecting surfaces and volumes. This framework provides a clear and intuitive illustration of color metamerism.
Functionality Representations and Applications for Shape Analysis
(The Eurographics Association and John Wiley & Sons Ltd., 2018) Hu, Ruizhen; Savva, Manolis; Kaick, Oliver van; Hildebrandt, Klaus and Theobalt, Christian
A central goal of computer graphics is to provide tools for designing and simulating real or imagined artifacts. An understanding of functionality is important in enabling such modeling tools. Given that the majority of man-made artifacts are designed to serve a certain function, the functionality of objects is often reflected by their geometry, the way that they are organized in an environment, and their interaction with other objects or agents. Thus, in recent years, a variety of methods in shape analysis have been developed to extract functional information about objects and scenes from these different types of cues. In this report, we discuss recent developments that incorporate functionality aspects into the analysis of 3D shapes and scenes. We provide a summary of the state-of-the-art in this area, including a discussion of key ideas and an organized review of the relevant literature. More specifically, the report is structured around a general definition of functionality from which we derive criteria for classifying the body of prior work. This definition also facilitates a comparative view of methods for functionality analysis. We focus on studying the inference of functionality from a geometric perspective, and pose functionality analysis as a process involving both the geometry and interactions of a functional entity. In addition, we discuss a variety of applications that benefit from an analysis of functionality, and conclude the report with a discussion of current challenges and potential future works.
GL-Socket: A CG Plugin-based Framework for Teaching and Assessment
(The Eurographics Association, 2018) Andujar, Carlos; Chica, Antonio; Fairén, Marta; Vinacua, Alvar; Post, Frits and Žára, Jirí
In this paper we describe a plugin-based C++ framework for teaching OpenGL and GLSL in introductory Computer Graphics courses. The main strength of the framework architecture is that student assignments are mostly independent and thus can be completed, tested and evaluated in any order. When students complete a task, the plugin interface forces a clear separation of initialization, interaction and drawing code, which in turn facilitates code reusability. Plugin code can access scene, camera, and OpenGL window methods through a simple API. The plugin interface is flexible enough to allow students to complete tasks requiring shader development, object drawing, and multiple rendering passes. Students are provided with sample plugins with basic scene drawing and camera control features. One of the plugins that the students receive contains a shader development framework with self-assessment features. We describe the lessons learned after using the tool for four years in a Computer Graphics course involving more than one hundred Computer Science students per year.

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