EG2019

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https://diglib.eg.org/handle/10.2312/2632746

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A Preliminary Analysis of Methods for Curvature Estimation on Surfaces With Local Reliefs
(The Eurographics Association, 2019) Moscoso Thompson, Elia; Biasotti, Silvia; Cignoni, Paolo and Miguel, Eder
Curvature estimation is very popular in geometry processing for the analysis of local surface variations. Despite the large number of methods, no quantitative nor qualitative studies have been conducted for a comparative analysis of the different algorithms on surfaces with small geometric variations, such as chiselled or relief surfaces. In this work we compare eight curvature estimation methods that are commonly adopted by the computer graphics community on a number of triangle meshes derived from scans of surfaces with local reliefs.
Towards Diverse Anime Face Generation: Active Label Completion and Style Feature Network
(The Eurographics Association, 2019) Li, Hongyu; Han, Tianqi; Cignoni, Paolo and Miguel, Eder
It is interesting to use an anime face as personal virtual image to replace the traditional sequence code. To generate diverse anime faces, this paper proposes a style-gender based anime GAN (SGA-GAN), where the gender is directly conditioned to ensure the gender differentiation, and style features serve as a condition to guarantee the style diversity. To extract style features, we train a style feature network (SFN) as a multi-task classifier to simultaneously fulfill gender classification, style classification, and image quality estimation. To make full use of available data, partly labeled or unlabeled, during the SFN training, we propose a label completion method to actively complete the missing gender or style labels. The active label completion is essentially a weakly-supervised learning process through ensembling three distinct classifiers to improve the generalization capability. Experiments verify that the active label completion can improve the model accuracy and the style feature as a condition can make better the diversity of generated anime faces.
One-step Compact Skeletonization
(The Eurographics Association, 2019) Durix, Bastien; Morin, Geraldine; Chambon, Sylvie; Mari, Jean-Luc; Leonard, Kathryn; Cignoni, Paolo and Miguel, Eder
Computing a skeleton for a discretized boundary typically produces a noisy output, with a skeletal branch produced for each boundary pixel. A simplification step often follows to reduce these noisy branches. As a result, generating a clean skeleton is usually a 2-step process. In this article, we propose a skeletonization process that produces a clean skeleton in the first step, avoiding the creation of branches due to noise. The resulting skeleton compares favorably with the most common pruning methods on a large database of shapes. Our process also reduces execution time and requires only one parameter, e, that designates the desired boundary precision in the Hausdorff distance.
Asteroid Escape: A Serious Game to Foster Teamwork Abilities
(The Eurographics Association, 2019) Pratticò, Filippo Gabriele; Strada, Francesco; Lamberti, Fabrizio; Bottino, Andrea; Cignoni, Paolo and Miguel, Eder
Teamwork skills have become a fundamental asset in the labor market. Modern organizations are increasingly implementing team building activities, aimed to improve or assess their employees' skills. Research suggests that serious games could be promising tools capable to support the creation of engaging and effective team building experiences. However, the design and development of serious games targeting these activities is still sparse and requires further investigation. This work introduces Asteroid Escape, an immersive serious game for team building, whose design was based on theoretical models on teamwork effectiveness. Although conducted on a restricted user sample, preliminary experiments suggest that tools like the devised one could positively contribute to ongoing research and implementation efforts targeting the exploitation of technology-enhanced learning methods for the development of teamwork skills and, more in general, of so-called soft skills.
Image Recoloring Based on Object Color Distributions
(The Eurographics Association, 2019) Afifi, Mahmoud; Price, Brian; Cohen, Scott; Brown, Michael S.; Cignoni, Paolo and Miguel, Eder
We present a method to perform automatic image recoloring based on the distribution of colors associated with objects present in an image. For example, when recoloring an image containing a sky object, our method incorporates the observation that objects of class 'sky' have a color distribution with three dominant modes for blue (daytime), yellow/red (dusk/dawn), and dark (nighttime). Our work leverages recent deep-learning methods that can perform reasonably accurate object-level segmentation. By using the images in datasets used to train deep-learning object segmentation methods, we are able to model the color distribution of each object class in the dataset. Given a new input image and its associated semantic segmentation (i.e., object mask), we perform color transfer to map the input image color histogram to a set of target color histograms that were constructed based on the learned color distribution of the objects in the image. We show that our framework is able to produce compelling color variations that are often more interesting and unique than results produced by existing methods.
Integrating Server-based Simulations Into Web-based Geo-applications
(The Eurographics Association, 2019) Bormann, Pascal; Gutbell, Ralf; Mueller-Roemer, Johannes Sebastian; Cignoni, Paolo and Miguel, Eder
In this work, we present a novel approach for combining fluid simulations running on a GPU server with terrain rendered by a web-based 3D GIS system. We introduce a hybrid rendering approach, combining server-side and client-side rendering, to interactively display the results of a shallow water simulation on client devices using web technology. To display water and terrain in unison, we utilize image merging based on depth values.We extend it to deal with numerical and compression artifacts as well as Level-of-detail rendering and use Depth Image Based Rendering to counteract network latency.
D.A.V.E: A Prototype for Automatic Environment Decoration
(The Eurographics Association, 2019) Glover, Callum James; Anderson, Eike Falk; Fusiello, Andrea and Bimber, Oliver
To fully immerse players in video games, elements of the game world must form a rich, coherent and believable universe, which is time consuming and expensive to achieve manually. We propose an artists' tool for Autodesk Maya to aid environment decoration, allowing artists to focus on the more important elements of the worlds they create.
Flexible Type: Methods and Applications of Modifying Glyph's Horizontal and Vertical Weight
(The Eurographics Association, 2019) Kumawat, Nirmal; dhanuka, praveen kumar; Fusiello, Andrea and Bimber, Oliver
Graphic designers create logos or artworks by using various tools such as Adobe Illustrator, InDesign etc. Many times, designers face a major problem where they want to change the visual appearance of the text to fit the design in the current context or to make the design look better, but text editing options provided today are very limiting to the user's creativity. The designers get around this by converting text to outlines and then modifying each glyph like a separate graphic. This leads to text no longer being live (essentially unlinked) and the edits for each glyph can be time consuming. The poster presents methods for modifying glyph's horizontal and vertical weight. Later, the poster aims to provide the application of such modification to generate multiple styles by modifying glyph's overall Weight, Width, CapHeight, xHeight, height of Ascender and Descender etc.
Vegetable Matter Decay: An Exceptional Student 'Innovations' Project
(The Eurographics Association, 2019) Anderson, Eike Falk; Cirdei, Bianca; Adzhiev, Valery; Tarini, Marco and Galin, Eric
We present an outstanding undergraduate research project that has resulted in the development of a parametrised method for simulating drying and decaying vegetable matter from the fruits category, taking into account the biological characteristics of the decaying fruit. This work was awarded 1st place in the undergraduate category of the ACM Student Research Competition at SIGGRAPH 2018.
Integrating Visualization Literacy into Computer Graphics Education Using the Example of Dear Data
(The Eurographics Association, 2019) Krekhov, Andrey; Michalski, Michael; Krüger, Jens; Tarini, Marco and Galin, Eric
The amount of visual communication we are facing is rapidly increasing, and skills to process, understand, and generate visual representations are in high demand. Especially students focusing on computer graphics and visualization can benefit from a more diverse education on visual literacy, as they often have to work on graphical representations for broad masses after their graduation. Our proposed teaching approach incorporates basic design thinking principles into traditional visualization and graphics education. Our course was inspired by the book Dear Data that was the subject of a lively discussion at the closing capstone of IEEE VIS 2017. The paper outlines our 12-week teaching experiment and summarizes the results extracted from accompanying questionnaires and interviews. In particular, we provide insights into the creation process and pain points of visualization novices, discuss the observed interplay between visualization tasks and design thinking, and finally draw design implications for visual literacy education in general.
GPU Smoke Simulation on Compressed DCT Space
(The Eurographics Association, 2019) Ishida, Daichi; Ando, Ryoichi; Morishima, Shigeo; Cignoni, Paolo and Miguel, Eder
This paper presents a novel GPU-based algorithm for smoke animation. Our primary contribution is the use of Discrete Cosine Transform (DCT) compressed space for efficient simulation. We show that our method runs an order of magnitude faster than a CPU implementation while retaining visual details with a smaller memory usage. The key component of our method is an on-the-fly compression and expansion of velocity, pressure and density fields. Whenever these physical quantities are requested during a simulation, we perform data expansion and compression only where necessary in a loop. As a consequence, our simulation allows us to simulate a large domain without actually allocating full memory space for it. We show that albeit our method comes with some extra cost for DCT manipulations, such cost can be minimized with the aid of a devised shared memory usage.
Automatic Environment Map Registration
(The Eurographics Association, 2019) Larvy, Ulysse; Loscos, Céline; Chrysanthou, Yiorgos; Cignoni, Paolo and Miguel, Eder
In this paper, a method to automatically register an environment map (EM) around a local scene is presented. In the literature, this step is most of the time manually processed by a user. However, it is an essential step when lighting and/or background coherence is needed. We present a method to find the coherent spatial organization between a main light source present in the EM and a couple object/shadow in a local scene. We automatically recover the EM orientation which corresponds to the local scene illumination. We proceed to a 3D representation of the scene using the EM mapped on a hemisphere as a background scene, a simplified geometry description of the reference object and its shadow outline. As a first step, we compute a projection of the main object shadow to compare it against the real acquired shadow. In a second step, we minimize a metric based on Euclidean Distance Transform (EDT), to compare both shadows and to recover the EM orientation. We demonstrate that we can automatically find rotation and scaling parameters that position in a coherent manner the background around a local scene.
Anisotropic Filtering for On-the-fly Patch-based Texturing
(The Eurographics Association, 2019) Lutz, Nicolas; Sauvage, Basile; Larue, Frédéric; Dischler, Jean-Michel; Cignoni, Paolo and Miguel, Eder
On-the-fly patch-based texturing consists of choosing at run-time, for several patches within a tileable texture, one random candidate among a pre-computed set of possible contents. This category of methods generates unbounded textures, for which filtering is not straightforward, because the screen pixel footprint may overlap multiple patches in texture space, i.e. different randomly chosen contents. In this paper, we propose a real-time anisotropic filtering which is fully compliant with the standard graphics pipeline. The main idea is to pre-filter the contents independently, store them in an atlas, and combine them at run-time to produce the final pixel color. The patch-map, referencing to which patch belong the fetched texels, requires a specific filtering approach, in order to recover the patches that overlap at low resolutions. In addition, we show how this method can achieve blending at patch boundaries in order to further reduce visible seams, without modification of our filtering algorithm.
A Projection Mapping System onto a Human Body for Medical Applications
(The Eurographics Association, 2019) Fukuhara, Ryo; Kaneda, Kazufumi; Tamaki, Toru; Raytchev, Bisser; Higaki, Toru; Nishimoto, Soh; Sotsuka, Yohei; Fusiello, Andrea and Bimber, Oliver
In breast reconstructive surgery where patient's abdominal fat and blood vessels are transplanted to the breast, it is very important to identify the course of the blood vessels inside the abdomen. In this paper, we propose a system for projecting blood vessels extracted from computer tomography angiography (CTA) on a patient's abdominal surface to support the breast reconstructive surgery. The proposed system detects the position and orientation of a projector automatically using an image captured by a camera mounted with the projector and is able to project the exact course of the blood vessels onto an abdominal skin from an arbitrary direction. An experiment using an abdominal model fabricated from patient's CTA data with a 3D printer demonstrates the usefulness of the proposed system.
Mapping Creative Coding Courses: Toward Bespoke Programming Curricula in Graphic Design Education
(The Eurographics Association, 2019) Hansen, Stig Møller; Tarini, Marco and Galin, Eric
This paper presents a study of 30 syllabi gathered from introductory Creative Coding programming courses. A selection of the results concerning the courses' structure and content is presented and discussed. The majority of the analyzed courses exhibited evidence of being planned to adapt and submit graphic design topics to programming paradigms. Also, topics and algorithms of particular value to graphic design as a spatial practice were absent in many courses. Finally, most courses did not investigate visual output that is achievable only through computation. The present study argues that educators must adapt their Creative Coding syllabi and teaching materials to make programming meet the needs of graphic designers rather than the other way around. The findings in this paper provide a point of departure for a critical discussion among educators who wish to integrate programming in graphic design education.
Rethinking Texture Mapping
(The Eurographics Association and John Wiley & Sons Ltd., 2019) Yuksel, Cem; Lefebvre, Sylvain; Tarini, Marco; Giachetti, Andrea and Rushmeyer, Holly
The intrinsic problems of texture mapping, regarding its difficulties in content creation and the visual artifacts it causes in rendering, are well-known, but often considered unavoidable. In this state of the art report, we discuss various radically different ways to rethink texture mapping that have been proposed over the decades, each offering different advantages and trade-offs. We provide a brief description of each alternative texturing method along with an evaluation of its strengths and weaknesses in terms of applicability, usability, filtering quality, performance, and potential implementation related challenges.
Investigating Different Augmented Reality Approaches in Circuit Assembly: a User Study
(The Eurographics Association, 2019) Marques, Bernardo; Esteves, Rafael; Alves, João; Ferreira, Carlos; Dias, Paulo; Santos, Beatriz Sousa; Cignoni, Paolo and Miguel, Eder
Augmented Reality (AR) has been considered as having great potential in assisting performance and training of complex tasks. Assembling electronic circuits is such a task, since many errors may occur, as wrong choice or positioning of components or incorrect wiring and thus using AR approaches may be beneficial. This paper describes a controlled experiment aimed at comparing usability and acceptance of two AR-based approaches (one based on a single device and another approach using two interconnected devices), with a traditional approach using a paper manual in the assembly of an electronic circuit. Participants were significantly faster and made fewer errors while using the AR approaches, and most preferred the multi-device approach.
Hybrid Function Representation with Distance Properties
(The Eurographics Association, 2019) Tereshin, Alexander; Adzhiev, Valery; Fryazinov, Oleg; Pasko, Alexander; Cignoni, Paolo and Miguel, Eder
This paper describes a novel framework allowing for a hybrid representation of heterogeneous objects. We consider advantages and drawbacks of the conventional representations based on scalar fields of different kinds. The main result is introducing a hybrid representation called Hybrid Function Representation (HFRep) that preserves the advantages of the Function Representation (FRep) and Signed Distance Fields (SDFs) without their drawbacks. This new representation allows for obtaining a continuous smooth distance field in the Euclidean space for the FRep. We present the mathematical basics for our approach that uses the Discrete Distance Transform (DDT) and a step-function. The procedure for generation HFRep using continuous interpolation and smoothing techniques are also described. A few examples show how the approach works in practice.
Area Lights in Signed Distance Function Scenes
(The Eurographics Association, 2019) Bán, Róbert; Bálint, Csaba; Valasek, Gábor; Cignoni, Paolo and Miguel, Eder
This paper presents two algorithms to incorporate spherical and general area lights into scenes defined by signed distance functions. The first algorithm employs an efficient approximation to the contribution of spherical lights to direct illumination and renders them at real-time rates. The second algorithm is of superior quality at a higher computational cost which is better suited for interactive rates. Our results are compared to both real-time soft shadow algorithms and a ground truth obtained by Monte Carlo integration. We show in these comparisons that our real-time solution computes more accurate shadows while the more demanding variant outperforms Monte Carlo integration at the expense of accuracy.
Multi-Scale Point Cloud Analysis
(The Eurographics Association, 2019) Lejemble, Thibault; Mura, Claudio; Barthe, Loïc; Mellado, Nicolas; Fusiello, Andrea and Bimber, Oliver
Surfaces sampled with point clouds often exhibit multi-scale properties due to the high variation between their feature size. Traditional shape analysis techniques usually rely on geometric descriptors able to characterize a point and its close neighborhood at multiple scale using smoothing kernels of varying radii. We propose to add a spatial regularization to these point-wise descriptors in two different ways. The first groups similar points in regions that are structured in a hierarchical graph. The graph is then simplified and processed to extract pertinent regions. The second performs a spatial gradient descent in order to highlight stable parts of the surface. We show two experiments focusing on planar and anisotropic feature areas respectively.

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