EG2017

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https://diglib.eg.org/handle/10.2312/2631246

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Conformal Factor Persistence for Fast Hierarchical Cone Extraction
(The Eurographics Association, 2017) Vintescu, Ana-Maria; Dupont, Florent; Lavoué, Guillaume; Memari, Pooran; Tierny, Julien; Adrien Peytavie and Carles Bosch
This paper presents a new algorithm for the fast extraction of hierarchies of cone singularities for conformal surface parameterization. Cone singularities have been shown to greatly improve the distortion of such parameterizations since they locally absorb the area distortion. Therefore, existing automatic approaches aim at inserting cones where large area distortion can be predicted. However, such approaches are iterative, which results in slow computations, even often slower than the actual subsequent parameterization procedure. This becomes even more problematic as often the user does not know in advance the right number of needed cones and thus needs to explore cone hierarchies to obtain a satisfying result. Our algorithm relies on the key observation that the local extrema of the conformal factor already provide a good approximation of the cone singularities extracted with previous techniques, while needing only one linear solving where previous approaches needed one solving per hierarchy level. We apply concepts from persistent homology to organize very efficiently such local extrema into a global hierarchy. Experiments demonstrate the approximation quality of our approach quantitatively and report time-performance improvements of one order of magnitude, which makes our technique well suited for interactive contexts.
EUROGRAPHICS 2017: Education Papers Frontmatter
(Eurographics Association, 2017) Bourdin, Jean Jacques; Shesh, Amit;
Fast Flow-based Distance Quantification and Interpolation for High-Resolution Density Distributions
(The Eurographics Association, 2017) Frey, Steffen; Ertl, Thomas; Adrien Peytavie and Carles Bosch
We present a GPU-targeted algorithm for the efficient direct computation of distances and interpolates between high-resolution density distributions without requiring any kind of intermediate representation like features. It is based on a previously published multi-core approach, and substantially improves its performance already on the same CPU hardware due to algorithmic improvements. As we explicitly target a manycore-friendly algorithm design, we further achieve significant speedups by running on a GPU. This paper quickly reviews the previous approach, and explicitly discusses the analysis of algorithmic characteristics as well as hardware architectural considerations on which our redesign was based. We demonstrate the performance and results of our technique by means of several transitions between volume data sets.
Computer Generated Display Holography
(The Eurographics Association, 2017) Lobaz, Petr; Adrien Bousseau and Diego Gutierrez
« A hologram » is a ubiquitous term when talking about realistic 3-D illusion. « Holographic display » seems to be the holy grail of 3-D display technology, at least according to news headlines. But what « holographic » actually means? The tutorial explains basics of holography, the lensless imaging method, invented by Gabor and Denisyuk in the mid-twentieth century, that produces breathtaking 3-D images - holograms. Then it explains basic steps of transition from classical to digital holography and to computer generated display holography - a counterpart of computer graphics that does not calculate an image, but a hologram. The tutorial also covers holographic printing, holographic electronic displays and compares them to competing technologies.
Ambient Occlusion Baking via a Feed-Forward Neural Network
(The Eurographics Association, 2017) Erra, Ugo; Capece, Nicola Felice; Agatiello, Roberto; Adrien Peytavie and Carles Bosch
We present a feed-forward neural network approach for ambient occlusion baking in real-time rendering. The idea is based on implementing a multi-layer perceptron that allows a general encoding via regression and an efficient decoding via a simple GPU fragment shader. The non-linear nature of multi-layer perceptrons makes them suitable and effective for capturing nonlinearities described by ambient occlusion values. A multi-layer perceptron is also random-accessible, has a compact size, and can be evaluated efficiently on the GPU. We illustrate our approach of screen-space ambient occlusion based on neural network including its quality, size, and run-time speed.
Geometric Modeling of Multi-Material Printed Objects
(The Eurographics Association, 2017) Brochu, Tyson; Schmidt, Ryan; Adrien Peytavie and Carles Bosch
We introduce a set of tools for interactive modeling of multi-material objects. We use non-manifold surface meshes to define complex objects, which can have multiple connected solid regions of different materials. Our suite of tools can create and edit non-manifold surfaces, while maintaining a consistent labeling of distinct regions. We also introduce a technique for generating approximate material gradients, using a set of thin layers with varying material properties. We demonstrate our approaches by printing physical objects with a multi-material printer.
EUROGRAPHICS 2017: Posters Frontmatter
(Eurographics Association, 2017) Benard, Pierre; Sykora, Daniel;
Virtual Reality to teach anatomy
(The Eurographics Association, 2017) Fairén, Marta; Farrés, Mariona; Moyés, Jordi; Insa, Esther; Jean-Jacques Bourdin and Amit Shesh
Virtual Reality (VR) and Augmented Reality (AR) have been gradually introduced in the curriculum of schools given the benefits they bring to classical education. We present an experiment designed to expose students to a VR session where they can directly inspect 3D models of several human organs by using Virtual Reality systems. Our systems allow the students to see the models directly visualized in 3D and to interact with them as if they were real. The experiment has involved 254 students of a Nursing Degree, enrolled in the Human anatomy and physiology course during 2 years (2 consecutive courses). It includes 10 3D models representing different anatomical structures which have been enhanced with meta-data to help the students understand the structure. In order to evaluate the students' satisfaction facing such a new teaching methodology, the students were asked to fill in a questionnaire with two categories. The first one measured whether or not, the teaching session using VR facilitates the understanding of the structures. The second one measured the student's satisfaction with this VR session. From the results we can see that the items most valuated are the use of the activity as a learning tool, and the satisfaction of the students' expectations. We can therefore conclude that VR session for teaching is a powerful learning tool that helps to understand the anatomical structures.
Topology Optimization for Computational Fabrication
(The Eurographics Association, 2017) Wu, Jun; Aage, Niels; Lefebvre, Sylvain; Wang, Charlie; Adrien Bousseau and Diego Gutierrez
Additive manufacturing (AM) and topology optimization (TO) form a pair of complementary techniques in transforming digital models into physical replicas: AM enables a cost-effective fabrication of geometrically complex shapes, while TO provides a powerful design methodology for generating optimized models, which are typically complex from a geometric perspective. The potential of both techniques has recently been explored in graphics, resulting in fantastic applications especially regarding structural and aesthetic properties of fabricated models. In this tutorial, we start from the fundamentals of AM and TO, and proceed to advanced TO techniques which steer the optimization process, i.e., taking into account the manufacturing as well as aesthetic appearance.
Discovering New Monte Carlo Noise Filters with Genetic Programming
(The Eurographics Association, 2017) Kán, Peter; Davletaliyev, Maxim; Kaufmann, Hannes; Adrien Peytavie and Carles Bosch
This paper presents a novel method for the discovery of new analytical filters suitable for filtering of noise in Monte Carlo rendering. Our method utilizes genetic programming to evolve the set of analytical filtering expressions with the goal to minimize image error in training scenes. We show that genetic programming is capable of learning new filtering expressions with quality comparable to state of the art noise filters in Monte Carlo rendering. Additionally, the analytical nature of the resulting expressions enables the run-times one order of magnitude faster than compared state of the art methods. Finally, we present a new analytical filter discovered by our method which is suitable for filtering of Monte Carlo noise in diffuse scenes.
Perception-driven Accelerated Rendering
(The Eurographics Association and John Wiley & Sons Ltd., 2017) Weier, Martin; Stengel, Michael; Roth, Thorsten; Didyk, Piotr; Eisemann, Elmar; Eisemann, Martin; Grogorick, Steve; Hinkenjann, André; Kruijff, Ernst; Magnor, Marcus; Myszkowski, Karol; Slusallek, Philipp; Victor Ostromoukov and Matthias Zwicker
Advances in computer graphics enable us to create digital images of astonishing complexity and realism. However, processing resources are still a limiting factor. Hence, many costly but desirable aspects of realism are often not accounted for, including global illumination, accurate depth of field and motion blur, spectral effects, etc. especially in real-time rendering. At the same time, there is a strong trend towards more pixels per display due to larger displays, higher pixel densities or larger fields of view. Further observable trends in current display technology include more bits per pixel (high dynamic range, wider color gamut/fidelity), increasing refresh rates (better motion depiction), and an increasing number of displayed views per pixel (stereo, multi-view, all the way to holographic or lightfield displays). These developments cause significant unsolved technical challenges due to aspects such as limited compute power and bandwidth. Fortunately, the human visual system has certain limitations, which mean that providing the highest possible visual quality is not always necessary. In this report, we present the key research and models that exploit the limitations of perception to tackle visual quality and workload alike. Moreover, we present the open problems and promising future research targeting the question of how we can minimize the effort to compute and display only the necessary pixels while still offering a user full visual experience.
Partitioning Surfaces into Quad Patches
(The Eurographics Association, 2017) Campen, Marcel; Adrien Bousseau and Diego Gutierrez
The efficient and practical representation and processing of geometrically or topologically complex shapes often demands some form of virtual partitioning into pieces, each of which is of a simpler nature. Due to their regularity, highly structured networks of conforming quadrilateral patches, called quad layouts, or in particular instances quad meshes, are most beneficial in many scenarios; they enable the use of tensor-product representations based on NURBS or Bézier patches, grid-based multiresolution techniques, or discrete pixel-based map representations. However, partitions of this type are particularly complicated to create due to the inherent structural restrictions. Research in geometry processing has led to a variety of automatic or semi-automatic approaches to address this problem. This course provides a detailed introduction to this range of methods, treats their strengths and weaknesses, discusses their applicability and practical limitations, and outlines open problems in this field.
Robust Blending and Occlusion Compensation in Dynamic Multi-Projection Mapping
(The Eurographics Association, 2017) Lange, Vanessa; Siegl, Christian; Colaianni, Matteo; Stamminger, Marc; Bauer, Frank; Adrien Peytavie and Carles Bosch
Using multi-projection systems allows us to immerse users in an altered reality without the need to wear additional head-gear. The immersion of such systems relies on the quality of the calibration which in general will degenerate over time when used outside of a lab environment. This work introduces a novel balance term that allows us to hide high frequency brightness seams caused by self-shadowing of the projected geometry and the borders of the projection frustum. We further use this more robust blending between projectors to compensate for occluding spectators, who enter the projection volume, by filling the resulting shadows with light from other projectors.
Phong Tessellation and PN Polygons for Polygonal Models
(The Eurographics Association, 2017) Hettinga, Gerben J.; Kosinka, Jiri; Adrien Peytavie and Carles Bosch
We extend Phong tessellation and point normal (PN) triangles from the original triangular setting to arbitrary polygons by use of generalised barycentric coordinates and S-patches. In addition, a generalisation of the associated quadratic normal field is given as well as a simple algorithm for evaluating the polygonal extensions for a polygon with vertex normals on the GPU.
EUROGRAPHICS 2017: Short Papers Frontmatter
(Eurographics Association, 2017) Peytavie, Adrien; Bosch, Carles;
The New CGEMS - Preparing the Computer Graphics Educational Materials Source to Meet the Needs of Educators
(The Eurographics Association, 2017) Anderson, Eike Falk; Duchowski, Andrew; Liarokapis, Fotis; Redford, Adam; Jean-Jacques Bourdin and Amit Shesh
ACM SIGGRAPH and Eurographics are restarting CGEMS, the Computer Graphics Educational Materials Source, an on-line repository of curricular material for computer graphics education. In this context, the question that we ask ourselves is: ''How can CGEMS best meet the needs of educators''? The aim of this forum is to provide the audience with an idea of the purpose of CGEMS - a source of educational materials for educators by educators - and to give them an opportunity to contribute their views and ideas towards shaping the new CGEMS. Towards this purpose, we have identified a number of issues to resolve, which the panel will put forward to the participants of the forum for discussion.
"Synchronize" to VR Body: Full Body Illusion in VR Space
(The Eurographics Association, 2017) Xiong, Peikun; Sun, Chen; Cai, Dongsheng; Adrien Peytavie and Carles Bosch
Virtual Reality (VR) becomes accessible to mimic a "real-like" world now. People who have a VR experience usually can be impressed by the immersive feeling, they might consider themselves are actually existed in the VR space. Self-consciousness is important for people to identify their own characters in VR space, and illusory ownership can help people to "build" their "bodies". The rubber hand illusion can convince us a fake hand made by rubber is a part of our bodies under certain circumstances. Researches about autoscopic phenomena extend this illusory to the so-called full body illusion. We conducted 3 type of experiments to study the illusory ownership in VR space as it shows in Figure 1, and we learned: Human body must receive the synchronized visual signal and somatosensory stimulus at the same time; The visual signal must be the first person perceptive; the subject and the virtual body needs to be the same height as much as possible. All these illusory ownerships accompanied by the body temperature decreases, where the body is stimulated.
High Quality and Efficient Direct Rendering of Massive Real-world Point Clouds
(The Eurographics Association, 2017) Bouchiba, Hassan; Groscot, Raphaël; Deschaud, Jean-Emmanuel; Goulette, François; Pierre Benard and Daniel Sykora
We present a novel real-time screen-space rendering algorithm for real-world 3D scanned datasets. Our method takes advantage of the pull phase of a pull-push pyramidal filling algorithm in order to feed a hidden point removal operator. The push phase is then used to fill the final framebuffer. We demonstrate on a real-world complex dataset that our method produces better visual results and is more efficient comparing to state of the art algorithms.
EUROGRAPHICS 2017: Dirk Bartz Prize Frontmatter
(Eurographics Association, 2017) Bruckner, Stefan; Ropinski, Timo;
Swung-to-Cylinder Projection for Panoramic Image Viewing
(The Eurographics Association, 2017) Chang, Che-Han; Lai, Wei-Sheng; Chuang, Yung-Yu; Pierre Benard and Daniel Sykora
This paper proposes the swung-to-cylinder projection model for mapping a sphere to a plane, which is useful for viewing 360 panoramic images. Our model extends the swung-to-plane model and consists of two steps. In the first step, the sphere is projected onto a swung surface. In the second step, the projected image on the swung surface is mapped onto a cylinder through the perspective projection. The proposed model is simple, efficient and easy to control. Similar to the swung-to-plane model, it makes a better compromise between distortion minimization and line preserving. However, it does not suffer from the distortion problem of the swung-to-plane model when viewing full 360 panoramic images.

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