EG 2016 - Short Papers

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https://diglib.eg.org/handle/10.2312/15066

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Drift-Diffusion Based Real-Time Dynamic Terrain Deformation
(The Eurographics Association, 2016) Gilardi, Marco; Watten, Phil L.; Newbury, Paul; T. Bashford-Rogers and L. P. Santos
In the natural world, terrains are dynamic entities which change their morphology due to their interaction with other agents in the environment. However, in real-time applications terrains are often represented as static meshes, which present no interaction capabilities. This paper presents a novel real-time 2D method for dynamic terrain simulations, aimed for applications in the entertainment industry. This method is based on a Dynamically-Displaced Height-map and on the numerical solutions, obtained using an Euler method, of a modified drift-diffusion equation. The method allows objects to interact with the terrain and to deform it in real time, it is easy to implement and generates different kinds of realistic tracks depending on the soil composition.
Subjective and Objective Evaluation of Multi-exposure High Dynamic Range Image Deghosting Methods
(The Eurographics Association, 2016) Karaduzovic-Hadziabdic, Kanita; Telalovic, Jasminka Hasic; Mantiuk, Rafal; T. Bashford-Rogers and L. P. Santos
To avoid motion artefacts when merging multiple exposures into an HDR image, a number of deghosting algorithms have been proposed. These algorithms, however, do not work equally well on all types of scenes, and some may even introduce additional artefacts. Even though subjective methods of evaluation provide reliable means of testing, they need to be repeated for each new proposed method or even its slight modification and are cumbersome to perform. In this work, we evaluate several computational approaches of quantitative evaluation of multi-exposure HDR deghosting algorithms and demonstrate their results on five state-of-the-art algorithms.The quality of HDR images produced by deghosting methods is measured in a subjective experiment, and then evaluated using five objective metrics. The most reliable metrics is then selected by testing correlation between subjective and objective metric scores.
Garment Transfer for Quadruped Characters
(The Eurographics Association, 2016) Narita, Fumiya; Saito, Shunsuke; Kato, Takuya; Fukusato, Tsukasa; Morishima, Shigeo; T. Bashford-Rogers and L. P. Santos
Modeling clothing to characters is one of the most time-consuming tasks for artists in 3DCG animation production. Transferring existing clothing models is a simple and powerful solution to reduce labor. In this paper, we propose a method to generate a clothing model for various characters from a single template model. Our framework consists of three steps: scale measurement, clothing transformation, and texture preservation. By introducing a novel measurement of the scale deviation between two characters with different shapes and poses, our framework achieves pose-independent transfer of clothing even for quadrupeds (e.g., from human to horse). In addition to a plausible clothing transformation method based on the scale measurement, our method minimizes texture distortion resulting from large deformation. We demonstrate that our system is robust for a wide range of body shapes and poses, which is challenging for current state-of-the-art methods.
Trajectory Data Visualization on Mobile Devices with Animated Maps
(The Eurographics Association, 2016) Gonçalves, Tiago; Afonso, Ana Paula; Ferreira, António; Vieira, Ana Rita; T. Bashford-Rogers and L. P. Santos
With the increasing popularity of mobile devices (like smartphones and tablets) and georeferenced applications, more people record and analyse their own movement data. This pattern is noticeable with the increasing usage of mobile applications that, in addition to record the evolution of a person's location over time, also allow the visualization of that information, typically, in the form of 2D static maps, complemented with various representations to extract knowledge from the data. Despite the various studies addressing spatio-temporal data visualization, its application on mobile devices for the representation of personal trajectory data is still somewhat unexplored. Animated maps have been proposed as a potential intuitive and appealing technique for the visualization of information in a dynamic way, particularly for the detection of spatio-temporal data relations. We aim to address these issues by presenting a comparative study between static and animated representations of human movement on a mobile device context. Our results suggest that although it may not significantly improve user understanding of the data, the use of animated maps is a preferred and less interactively demanding option over static maps.
Multi-Focus Plenoptic Simulator and Lens Pattern Mixing for Dense Depth Map Estimation
(The Eurographics Association, 2016) Ferreira, Rodrigo; Cunha, Joel; Goncalves, Nuno; T. Bashford-Rogers and L. P. Santos
Light field cameras capture a scene's multi-directional light field with one image, allowing the estimation of depth. In this paper, we introduce a fully automatic method for depth estimation from a single plenoptic image running a RANSAC-like algorithm for feature matching. The novelty about our method is the use of different focal-length lenses for multiple depth map refining, generating a dense depth map for future all-in-focus renders. We also present a plenoptic simulator which produces a plenoptic dataset from a 3D computer rendered scene. This simulator, which is unique, as far as we known, allows testing of plenoptic oriented algorithms since it can reproduce datasets with desired scene characteristics, providing the depth ground truth for error measurement. This work is a on-going project with promising results.
Texel Shading
(The Eurographics Association, 2016) Hillesland, Karl E.; Yang, J. C.; T. Bashford-Rogers and L. P. Santos
We have developed a texture space shading system built on modern graphics hardware. It begins with a conventional rasterization stage, but records texel accesses as shading work rather than running a shade per pixel. Shading is performed by a separate compute stage, storing the results in a texture. As a baseline, the texels correspond to those required for mipmapped texturing. A final stage collects data from the texture. Storing results in a texture allows for reuse across frames. We also show how adapting shade rate to less than once per pixel further increases performance. We vary shading load to show when these techniques provide a performance win, with up to 4.1x speedup in our experiments at shading times less than 4 ms.
Smooth Interpolation of Curve Networks with Surface Normals
(The Eurographics Association, 2016) Stanko, Tibor; Hahmann, Stefanie; Bonneau, Georges-Pierre; Saguin-Sprynski, Nathalie; T. Bashford-Rogers and L. P. Santos
Recent surface acquisition technologies based on microsensors produce three-space tangential curve data which can be transformed into a network of space curves with surface normals. This paper addresses the problem of surfacing an arbitrary closed 3D curve network with given surface normals. Thanks to the normal vector input, the patch finding problem can be solved unambiguously and an initial piecewise smooth triangle mesh is computed. The input normals are propagated throughout the mesh and used to compute mean curvature vectors. We then introduce a new variational optimization method in which the standard bi-Laplacian is penalized by a term based on the mean curvature vectors. The intuition behind this original approach is to guide the standard Laplacian-based variational methods by the curvature information extracted from the input normals. The normal input increases shape fidelity and allows to achieve globally smooth and visually pleasing shapes.
Minimum Displacements For Cloth-obstacle Penetration Resolving
(The Eurographics Association, 2016) Sun, Liming; Nyberg, Timo R.; Xiong, Gang; Ye, Juntao; T. Bashford-Rogers and L. P. Santos
Pre-existing penetrations often show up in many applications, particularly in garments fitting. The popular continuous collision detection (CCD) based methods are incapable of handling them, as there is no history information to rely on. On the other hand, surfaces of human bodies have normals defined to designate their orientation (i.e. front- and back-face), which are totally overlooked by CCD methods (thus they are orientation-free). In this paper we present a history-free method for separating two penetrating meshes, given that one of them represents a rigid object and has clarified surface orientation. This method computes all edge-face (E-F) intersections with discrete collision detection, and identifies illegal vertices with the help of surface orientation, and then builds a number of penetration stencils. On response, the stencil vertices are relocated into a penetrationfree state, via a global displacement minimizer. The proposed algorithm outperforms existing methods for handling solid/cloth collisions, thus is an effective tool for applications like virtual-try-on and example-based garment animation synthesis.
A Generic Physically-based Approach to the Opening Design Problem
(The Eurographics Association, 2016) Κalampokis, Konstantinos; Papaioannou, Georgios; Gkaravelis, Anastasios; T. Bashford-Rogers and L. P. Santos
Today architectural design harnesses photorealistic rendering to accurately assess energy transport for the design of energyefficient buildings. In this context, we present an automatic physically-based solution to the opening design problem, i.e. the goal-driven process of defining openings on the input geometry given a set of lighting constraints, to better exploit natural daylight. Based on a hierarchical approach that combines a linear optimization strategy and a genetic algorithm, our method computes the optimal number, position, size and shape of openings, using a path tracing-based estimator to precisely model the light transport for arbitrary materials and geometry. The method quickly converges to an opening configuration that optimally approximates the desired illumination, with no special geometry editing requirements and the ability to trade quality for performance for interactive applications. We validate our results against ground truth experiments for various scenes and time-of-day intervals.
Two-Level Adaptive Sampling for Illumination Integrals using Bayesian Monte Carlo
(The Eurographics Association, 2016) Marques, Ricardo; Bouville, Christian; Santos, Luis P.; Bouatouch, Kadi; T. Bashford-Rogers and L. P. Santos
Bayesian Monte Carlo (BMC) is a promising integration technique which considerably broadens the theoretical tools that can be used to maximize and exploit the information produced by sampling, while keeping the fundamental property of data dimension independence of classical Monte Carlo (CMC). Moreover, BMC uses information that is ignored in the CMC method, such as the position of the samples and prior stochastic information about the integrand, which often leads to better integral estimates. Nevertheless, the use of BMC in computer graphics is still in an incipient phase and its application to more evolved and widely used rendering algorithms remains cumbersome. In this article we propose to apply BMC to a two-level adaptive sampling scheme for illumination integrals. We propose an efficient solution for the second level quadrature computation and show that the proposed method outperforms adaptive quasi-Monte Carlo in terms of image error and high frequency noise.
Interactive Modeling of Support-free Shapes for Fabrication
(The Eurographics Association, 2016) Reiner, Tim; Lefebvre, Sylvain; T. Bashford-Rogers and L. P. Santos
We introduce an interactive sculpting approach that enables modeling of support-free objects: objects which do not require any support structures during 3D printing. We propose three operators - trim, preserve, grow - to maintain the support-free property during interactive modeling. These operators let us define brushes that perform either in an unconstrained manner (adapting the shape to the brush effect), or selectively discard changes inside the brush volume. Our technique can be applied to many modeling operations and we demonstrate it on brushes for adding or removing matter. We describe an efficient implementation of a voxel-based modeling tool that produces only support-free shapes, and show example shapes modeled within minutes.
Mesh Saliency Analysis via Local Curvature Entropy
(The Eurographics Association, 2016) Limper, Max; Kuijper, Arjan; Fellner, Dieter W.; T. Bashford-Rogers and L. P. Santos
We present a novel approach for estimating mesh saliency. Our method is fast, flexible, and easy to implement. By applying the well-known concept of Shannon entropy to 3D mesh data, we obtain an efficient method to determine mesh saliency. Comparing our method to the most recent, state-of-the-art approach, we show that results of at least similar quality can be achieved within a fraction of the original computation time. We present saliency-guided mesh simplification as a possible application.
Robust Gap Removal from Binary Volumes
(The Eurographics Association, 2016) Sobiecki, Andre; Jalba, Andrei C.; Telea, Alexandru; T. Bashford-Rogers and L. P. Santos
We present a method for the robust detection and removal of cracks and holes from binary voxel shapes based on the shapes' surface and curve skeletons. For this, we first classify gaps or indentations in the input shape by their position with respect to the shape's curve skeleton, into details (which should be preserved) and defects (which should be removed). Next, we remove defects, and preserve details, by using a local reconstruction process that uses the shape's surface skeleton. We illustrate our method by comparing it against classical morphological solutions on a wide collection of real-world shapes.
A Simple and Effective Method to Detect Orthogonal Vanishing Points in Uncalibrated Images of Man-Made Environments
(The Eurographics Association, 2016) Simon, Gilles; Fond, Antoine; Berger, Marie-Odile; T. Bashford-Rogers and L. P. Santos
This paper presents an effective and easy-to-implement algorithm to compute orthogonal vanishing points in uncalibrated images of man-made scenes. The main contribution is to estimate the zenith and the horizon line before detecting the vanishing points, using simple properties of the central projection and exploiting accumulations of oriented segments around the horizon. Our method is fast and yields an accuracy comparable, and even better in some cases, to that of state-of-the-art algorithms.
Adaptive UW Image Deblurring via Sparse Representation
(The Eurographics Association, 2016) Farhadifard, Fahimeh; Radolko, Martin; T. Bashford-Rogers and L. P. Santos
We present an adaptive underwater (UW) image deblurring algorithm based on sparse representation where a blur estimation is used to guide the algorithm for the best image reconstruction. The strong blur in this medium is caused by forward scatter and is challenging since it increases by camera scene distance. It is a common practice to use methods such as dark channel prior to estimate the depth map, and use this information to improve the image quality. However, we found it not successful in the case of blur since these methods are based on haze phenomenon. We propose a simple but effective algorithm via sparse representation which establishes a blur strength estimation and uses this information for adaptive deblurring. Extensive experiments manifest the effectiveness of our method in case of small but challenging blur changes.
Example-based Body Model Optimization and Skinning
(The Eurographics Association, 2016) Fechteler, Philipp; Hilsmann, Anna; Eisert, Peter; T. Bashford-Rogers and L. P. Santos
In this paper, we present an example-based framework for the generation of a realistic kinematic 3D human body model that optimizes shape, pose and skinning parameters. For enhanced realism, the skinning is realized as a combination of Linear Blend Skinning (LBS) and Dual quaternion Linear Blending (DLB) which nicely compensates the deficiencies of using only one of these approaches (e.g. candy wrapper, bulging artifacts) and supports interpolation of more than two joint transformations. The optimization framework enforces two objectives: resembling both shape and pose as closely as possible by iteratively minimizing the objective function with respect to (a) the vertices, (b) the skinning weights and (c) the joint parameters. Smoothness is ensured by using a weighted Laplacian besides a typical data term in the objective function, which introduces the only parameter to be specified. With experimental results on publicly available datasets we demonstrate the effectiveness of the resulting shape model, exposing convincing naturalism. By using examples for the optimization of all parameters, our framework is easy to use and does not require sophisticated parameter tuning or user intervention.
Interactive Deformation of Structurally Complex Heart Models Constructed from Medical Images
(The Eurographics Association, 2016) Nakashima, Kazutaka; Koyama, Yuki; Igarashi, Takeo; Ijiri, Takashi; Inada, Shin; Nakazawa, Kazuo; T. Bashford-Rogers and L. P. Santos
We present a data structure for interactive deformation of complicated organ models, such as hearts, and a technique for automatically constructing the data structure from given medical images. The data structure is a dual model comprising of a graph structure for elastic simulation and a surface mesh for visualization. The system maps the simulation results to the mesh using a skinning technique. First, the system generates a dense graph and mesh from input medical images; then, it independently reduces them. Finally, the system establishes correspondence between the reduced graph and mesh by backtracking the reduction process. We also present an interactive browser for exploring heart shapes, and report initial feedback from target users.
Peripheral Retinal Image Simulation Based on Retina Shapes
(The Eurographics Association, 2016) Dias, Catarina; Wick, Michael; Rifai, Katharina; Wahl, Siegfried; T. Bashford-Rogers and L. P. Santos
We present a method to render the image of a scene reaching the retina, the retinal image, taking into account human offaxis optical aberrations. To this end, we consider realistic wide-angle eye models that offer an anatomical description of the refractive structures of the eye as a set of lenses and accurately reproduce the optical aberrations in the periphery. We then combine these with representative retinal shapes and with distributed ray tracing. Due to the interplay between the eye model and the curved retina, we obtain a realistic simulation of the retinal image, not only foveally but also in the periphery.
EUROGRAPHICS 2016: Short Papers Frontmatter
(Eurographics Association, 2016) Luis Paulo Santos; Tom Bashford-Rogers;
Robust Transmission of Motion Capture Data using Interleaved LDPC and Inverse Kinematics
(The Eurographics Association, 2016) Furtado, Antonio Carlos; Cheng, Irene; Dufaux, Frederic; Basu, Anup; T. Bashford-Rogers and L. P. Santos
Recent advances in smart-sensor technology have improved precision in Motion Capture (MoCap) data for realistic animation. However, precision also imposes challenges on bandwidth. While research efforts have focussed on MoCap compression in recent years, little attention has been given to lossy transmission taking advantage of the human perceptual threshold, which allows many online applications, e.g., interactive games, on-demand broadcast, movies and tutoring using dynamic motion sequences. Given the growing applications on mobile devices and wireless networks, associated with insufficient bandwidth, unreliable connection and potential interference or shadowing, data loss is inevitable. We introduce a new Representation for MoCap data, integrating Interleaved Low-Density Parity-Check (I-LDPC), with Keyframe-based Interpolation and Inverse Kinematics, to better address the problem of MoCap data loss during transmission. We believe this is the first study to address robust transmission of MoCap data considering loss. Experimental results assessed using mean opinion scores demonstrate that our approach achieves substantial improvement over alternative transmission methods.

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