35-Issue 7

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/2630929

Browse

Now showing 1 - 20 of 52

Trip Synopsis: 60km in 60sec
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Huang, Hui; Lischinski, Dani; Hao, Zhuming; Gong, Minglun; Christie, Marc; Cohen-Or, Daniel; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Computerized route planning tools are widely used today by travelers all around the globe, while 3D terrain and urban models are becoming increasingly elaborate and abundant. This makes it feasible to generate a virtual 3D flyby along a planned route. Such a flyby may be useful, either as a preview of the trip, or as an after-the-fact visual summary. However, a naively generated preview is likely to contain many boring portions, while skipping too quickly over areas worthy of attention. In this paper, we introduce 3D trip synopsis: a continuous visual summary of a trip that attempts to maximize the total amount of visual interest seen by the camera. The main challenge is to generate a synopsis of a prescribed short duration, while ensuring a visually smooth camera motion. Using an application-specific visual interest metric, we measure the visual interest at a set of viewpoints along an initial camera path, and maximize the amount of visual interest seen in the synopsis by varying the speed along the route. A new camera path is then computed using optimization to simultaneously satisfy requirements, such as smoothness, focus and distance to the route. The process is repeated until convergence. The main technical contribution of this work is a new camera control method, which iteratively adjusts the camera trajectory and determines all of the camera trajectory parameters, including the camera position, altitude, heading, and tilt. Our results demonstrate the effectiveness of our trip synopses, compared to a number of alternatives.
Pixel History Linear Models for Real-Time Temporal Filtering
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Iglesias-Guitian, Jose A.; Moon, Bochang; Koniaris, Charalampos; Smolikowski, Eric; Mitchell, Kenny; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
We propose a new real-time temporal filtering and antialiasing (AA) method for rasterization graphics pipelines. Our method is based on Pixel History Linear Models (PHLM), a new concept for modeling the history of pixel shading values over time using linear models. Based on PHLM, our method can predict per-pixel variations of the shading function between consecutive frames. This combines temporal reprojection with per-pixel shading predictions in order to provide temporally coherent shading, even in the presence of very noisy input images. Our method can address both spatial and temporal aliasing problems under a unique filtering framework that minimizes filtering error through a recursive least squares algorithm. We demonstrate our method working with a commercial deferred shading engine for rasterization and with our own OpenGL deferred shading renderer.We have implemented our method in GPU and it has shown significant reduction of temporal flicker in very challenging scenarios including foliage rendering, complex non-linear camera motions, dynamic lighting, reflections, shadows and fine geometric details. Our approach, based on PHLM, avoids the creation of visible ghosting artifacts and it reduces the filtering overblur characteristic of temporal deflickering methods. At the same time, the results are comparable to state-of-the-art realtime filters in terms of temporal coherence.
Multiple Scattering Approximation in Heterogeneous Media by Narrow Beam Distributions
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Shinya, Mikio; Dobashi, Yoshinori; Shiraishi, Michio; Kawashima, Motonobu; Nishita, Tomoyuki; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Fast realistic rendering of objects in scattering media is still a challenging topic in computer graphics. In presence of participating media, a light beam is repeatedly scattered by media particles, changing direction and getting spread out. Explicitly evaluating this beam distribution would enable efficient simulation of multiple scattering events without involving costly stochastic methods. Narrow beam theory provides explicit equations that approximate light propagation in a narrow incident beam. Based on this theory, we propose a closed-form distribution function for scattered beams. We successfully apply it to the image synthesis of scenes in which scattering occurs, and show that our proposed estimation method is more accurate than those based on the Wentzel-Kramers-Brillouin (WKB) theory.
Incremental Deformation Subspace Reconstruction
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Mukherjee, Rajaditya; Wu, Xiaofeng; Wang, Huamin; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Recalculating the subspace basis of a deformable body is a mandatory procedure for subspace simulation, after the body gets modified by interactive applications. However, using linear modal analysis to calculate the basis from scratch is known to be computationally expensive. In the paper, we show that the subspace of a modified body can be efficiently obtained from the subspace of its original version, if mesh changes are small. Our basic idea is to approximate the stiffness matrix by its lowfrequency component, so we can calculate new linear deformation modes by solving an incremental eigenvalue decomposition problem. To further handle nonlinear deformations in the subspace, we present a hybrid approach to calculate modal derivatives from both new and original linear modes. Finally, we demonstrate that the cubature samples trained for the original mesh can be reused in fast reduced force and stiffness matrix evaluation, and we explore the use of our techniques in various simulation problems. Our experiment shows that the updated subspace basis still allows a simulator to generate visual plausible deformation effects. The whole system is efficient and it is compatible with other subspace construction approaches.
Reduced Aggregate Scattering Operators for Path Tracing
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Blumer, Adrian; Novák, Jan; Habel, Ralf; Nowrouzezahrai, Derek; Jarosz, Wojciech; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Aggregate scattering operators (ASOs) describe the overall scattering behavior of an asset (i.e., an object or volume, or collection thereof) accounting for all orders of its internal scattering. We propose a practical way to precompute and compactly store ASOs and demonstrate their ability to accelerate path tracing. Our approach is modular avoiding costly and inflexible scene-dependent precomputation. This is achieved by decoupling light transport within and outside of each asset, and precomputing on a per-asset level. We store the internal transport in a reduced-dimensional subspace tailored to the structure of the asset geometry, its scattering behavior, and typical illumination conditions, allowing the ASOs to maintain good accuracy with modest memory requirements. The precomputed ASO can be reused across all instances of the asset and across multiple scenes. We augment ASOs with functionality enabling multi-bounce importance sampling, fast short-circuiting of complex light paths, and compact caching, while retaining rapid progressive preview rendering. We demonstrate the benefits of our ASOs by efficiently path tracing scenes containing many instances of objects with complex inter-reflections or multiple scattering.
Efficient Volumetric PolyCube-Map Construction
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Fu, Xiao-Ming; Bai, Chong-Yang; Liu, Yang; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
PolyCubes provide compact representations for closed complex shapes and are essential to many computer graphics applications. Existing automatic PolyCube construction methods usually suffer from poor quality or time-consuming computation. In this paper, we provide a highly efficient method to compute volumetric PolyCube-maps. Given an input tetrahedral mesh, we utilize two novel normal-driven volumetric deformation schemes and a polycube-allowable mesh segmentation to drive the input to a volumetric PolyCube structure. Our method can robustly generate foldover-free and low-distortion PolyCube-maps in practice, and provide a flexible control on the number of corners of Polycubes. Compared with state-of-the-art methods, our method is at least one order of magnitude faster and has better mapping qualities. We demonstrate the efficiency and efficacy of our method in PolyCube construction and all-hexahedral meshing on various complex models.
3D Body Shapes Estimation from Dressed-Human Silhouettes
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Song, Dan; Tong, Ruofeng; Chang, Jian; Yang, Xiaosong; Tang, Min; Zhang, Jian Jun; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Estimation of 3D body shapes from dressed-human photos is an important but challenging problem in virtual fitting. We propose a novel automatic framework to efficiently estimate 3D body shapes under clothes. We construct a database of 3D naked and dressed body pairs, based on which we learn how to predict 3D positions of body landmarks (which further constrain a parametric human body model) automatically according to dressed-human silhouettes. Critical vertices are selected on 3D registered human bodies as landmarks to represent body shapes, so as to avoid the time-consuming vertices correspondences finding process for parametric body reconstruction. Our method can estimate 3D body shapes from dressed-human silhouettes within 4 seconds, while the fastest method reported previously need 1 minute. In addition, our estimation error is within the size tolerance for clothing industry. We dress 6042 naked bodies with 3 sets of common clothes by physically based cloth simulation technique. To the best of our knowledge, We are the first to construct such a database containing 3D naked and dressed body pairs and our database may contribute to the areas of human body shapes estimation and cloth simulation.
TSS BVHs: Tetrahedron Swept Sphere BVHs for Ray Tracing Subdivision Surfaces
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Du, Peng; Kim, Yong-Jun; Yoon, Sung Eui; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
We present a novel, compact bounding volume hierarchy, TSS BVH, for ray tracing subdivision surfaces computed by the Catmull-Clark scheme. We use Tetrahedron Swept Sphere (TSS) as a bounding volume to tightly bound limit surfaces of such subdivision surfaces given a user tolerance. Geometric coordinates defining our TSS bounding volumes are implicitly computed from the subdivided mesh via a simple vertex ordering method, and each level of our TSS BVH is associated with a single distance bound, utilizing the Catmull-Clark scheme. These features result in a linear space complexity as a function of the tree depth, while many prior BVHs have exponential space complexity. We have tested our method against different benchmarks with path tracing and photon mapping. We found that our method achieves up to two orders of magnitude of memory reduction with a high culling ratio over the prior AABB BVH methods, when we represent models with two to four subdivision levels. Overall, our method achieves three times performance improvement thanks to these results. These results are acquired by our theorem that rigorously computes our TSS bounding volumes.
Image Recoloring with Valence-Arousal Emotion Model
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Kim, Hye-Rin; Kang, Henry; Lee, In-Kwon; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
We introduce an affective image recoloring method for changing the overall mood in the image in a numerically measurable way. Given a semantically segmented source image and a target emotion, our system finds reference image segments from the collection of images that have been tagged via crowdsourcing with numerically measured emotion labels. We then recolorize the source segments using colors from the selected target segments while preserving the gradient of the source image to generate a seamless and natural result. User study confirms the effectiveness of our method in accomplishing the stated goal of altering the mood of the image to match the target emotion level.
Real-time Texture Synthesis and Concurrent Random-access Rendering for Low-cost GPU Chip Design
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Zhang, Linling; Fenney, Simon; Escribano, Fernando; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Numerous algorithms have been researched in the area of texture synthesis. However, it remains difficult to design a low-cost synthesis scheme capable of generating high quality results while simultaneously achieving real-time performance. Additional challenges include making a scheme parallel and being able to partially render/synthesize high-resolution textures. Furthermore, it would be beneficial for a synthesis scheme to be able to incorporate Texture Compression and minimize the bandwidth usage, especially on mobile devices. In this paper, we propose a practical method which has low computational complexity and produces textures with small storage requirements. Through use of an index table, random access of the texture is another essential advantage, with which parallel rendering becomes feasible including generation of mip-map sequences. Integrating the index table with existing compression algorithms, for example ETC or PVRTC, the bandwidth is further reduced and avoids the need for a separate, computationally expensive pass to compress the synthesized output. It should be noted that our texture synthesis achieves real-time performance and low power consumption even on mobile devices, for which texture synthesis has been traditionally considered too expensive.
Retargeting 3D Objects and Scenes with a General Framework
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Huang, Chun-Kai; Chen, Yi-Ling; Shen, I-Chao; Chen, Bing-Yu; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
In this paper, we introduce an interactive method suitable for retargeting both 3D objects and scenes. Initially, the input object or scene is decomposed into a collection of constituent components enclosed by corresponding control bounding volumes which capture the intra-structures of the object or semantic grouping of objects in the 3D scene. The overall retargeting is accomplished through a constrained optimization by manipulating the control bounding volumes. Without inferring the intricate dependencies between the components, we define a minimal set of constraints that maintain the spatial arrangement and connectivity between the components to regularize the valid retargeting results. The default retargeting behavior can then be easily altered by additional semantic constraints imposed by users. This strategy makes the proposed method highly flexible to process a wide variety of 3D objects and scenes under an unified framework. In addition, the proposed method achieved more general structure-preserving pattern synthesis in both object and scene levels. We demonstrate the effectiveness of our method by applying it to several complicated 3D objects and scenes.
Proxy-guided Image-based Rendering for Mobile Devices
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Reinert, Bernhard; Kopf, Johannes; Ritschel, Tobias; Cuervo, Eduardo; Chu, David; Seidel, Hans-Peter; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
VR headsets and hand-held devices are not powerful enough to render complex scenes in real-time. A server can take on the rendering task, but network latency prohibits a good user experience. We present a new image-based rendering (IBR) architecture for masking the latency. It runs in real-time even on very weak mobile devices, supports modern game engine graphics, and maintains high visual quality even for large view displacements. We propose a novel server-side dual-view representation that leverages an optimally-placed extra view and depth peeling to provide the client with coverage for filling disocclusion holes. This representation is directly rendered in a novel wide-angle projection with favorable directional parameterization. A new client-side IBR algorithm uses a pre-transmitted level-of-detail proxy with an encaging simplification and depth-carving to maintain highly complex geometric detail. We demonstrate our approach with typical VR / mobile gaming applications running on mobile hardware. Our technique compares favorably to competing approaches according to perceptual and numerical comparisons.
An Efficient Structure-Aware Bilateral Texture Filtering for Image Smoothing
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Lin, Ting-Hao; Way, Der-Lor; Shih, Zen-Chung; Tai, Wen-Kai; Chang, Chin-Chen; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Photos contain well-structured and plentiful visual information. Edges are active and expressive stimuli for human visual perception. However, it is hard to separate structure from details because edge strength and object scale are entirely different concepts. This paper proposes a structure-aware bilateral texture algorithm to remove texture patterns and preserve structures. Our proposed method is simple and fast, as well as effective in removing textures. Instead of patch shift, smaller patches represent pixels located at structure edges, and original patches represent the texture regions. Specifically, this paper also improves joint bilateral filter to preserve small structures. Moreover, a windowed inherent variation is adapted to distinguish textures and structures for detecting structure edges. Finally, the proposed method produces excellent experimental results. These results are compared to some results of previous studies. Besides, structure-preserving filtering is a critical operation in many image processing applications. Our proposed filter is also demonstrated in many attractive applications, such as seam carving, detail enhancement, artistic rendering, etc.
Appearance Harmonization for Single Image Shadow Removal
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Ma, Li-Qian; Wang, Jue; Shechtman, Eli; Sunkavalli, Kalyan; Hu, Shi-Min; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Shadow removal is a challenging problem and previous approaches often produce de-shadowed regions that are visually inconsistent with the rest of the image. We propose an automatic shadow region harmonization approach that makes the appearance of a de-shadowed region (produced using any previous technique) compatible with the rest of the image. We use a shadow-guided patch-based image synthesis approach that reconstructs the shadow region using patches sampled from nonshadowed regions. This result is then refined based on the reconstruction confidence to handle unique textures. Qualitative comparisons over a wide range of images, and a quantitative evaluation on a benchmark dataset show that our technique significantly improves upon the state-of-the-art.
Foveated Real-Time Ray Tracing for Head-Mounted Displays
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Weier, Martin; Roth, Thorsten; Kruijff, Ernst; Hinkenjann, André; Pérard-Gayot, Arsène; Slusallek, Philipp; Li, Yongmin; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Head-mounted displays with dense pixel arrays used for virtual reality applications require high frame rates and low latency rendering. This forms a challenging use case for any rendering approach. In addition to its ability of generating realistic images, ray tracing offers a number of distinct advantages, but has been held back mainly by its performance. In this paper, we present an approach that significantly improves image generation performance of ray tracing. This is done by combining foveated rendering based on eye tracking with reprojection rendering using previous frames in order to drastically reduce the number of new image samples per frame. To reproject samples a coarse geometry is reconstructed from a G-Buffer. Possible errors introduced by this reprojection as well as parts that are critical to the perception are scheduled for resampling. Additionally, a coarse color buffer is used to provide an initial image, refined smoothly by more samples were needed. Evaluations and user tests show that our method achieves real-time frame rates, while visual differences compared to fully rendered images are hardly perceivable. As a result, we can ray trace non-trivial static scenes for the Oculus DK2 HMD at 1182x1464 per eye within the the VSync limits without perceived visual differences.
Programmable Animation Texturing using Motion Stamps
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Milliez, Antoine; Guay, Martin; Cani, Marie-Paule; Gross, Markus; Sumner, Robert W.; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Our work on programmable animation texturing enhances the concept of texture mapping by letting artists stylize arbitrary animations using elementary animations, instantiated at the scale of their choice. The core of our workflow resides in two components: we first impose structure and temporal coherence over the animation data using a novel radius-based animationaware clustering. The computed clusters conform to the user-specified scale, and follow the underlying animation regardless of its topology. Extreme mesh deformations, complex particle simulations, or simulated mesh animations with ever-changing topology can therefore be handled in a temporally coherent way. Then, in analogy to fragment shaders that specify an output color based on a texture and a collection of properties defined per vertex (position, texture coordinate, etc.), we provide a programmable interface to the user, letting him or her specify an output animation based on the collection of properties we extract per cluster (position, velocity, etc.). We equip elementary animations with a collection of parameters that are exposed in our programmable system and enables users to script the animated textures depending on properties of the input cluster. We demonstrate the power of our system with complex animated textures created with minimal user input.
Efficient Multi-image Correspondences for On-line Light Field Video Processing
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Dąbała, Łukasz; Ziegler, Matthias; Didyk, Piotr; Zilly, Frederik; Keinert, Joachim; Myszkowski, Karol; Seidel, Hans-Peter; Rokita, Przemysław; Ritschel, Tobias; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Light field videos express the entire visual information of an animated scene, but their shear size typically makes capture, processing and display an off-line process, i. e., time between initial capture and final display is far from real-time. In this paper we propose a solution for one of the key bottlenecks in such a processing pipeline, which is a reliable depth reconstruction possibly for many views. This is enabled by a novel correspondence algorithm converting the video streams from a sparse array of off-the-shelf cameras into an array of animated depth maps. The algorithm is based on a generalization of the classic multi-resolution Lucas-Kanade correspondence algorithm from a pair of images to an entire array. Special inter-image confidence consolidation allows recovery from unreliable matching in some locations and some views. It can be implemented efficiently in massively parallel hardware, allowing for interactive computations. The resulting depth quality as well as the computation performance compares favorably to other state-of-the art light field-to-depth approaches, as well as stereo matching techniques. Another outcome of this work is a data set of light field videos that are captured with multiple variants of sparse camera arrays.
Visual Contrast Sensitivity and Discrimination for 3D Meshes and their Applications
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Nader, Georges; Wang, Kai; Hétroy-Wheeler, Franck; Dupont, Florent; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
In this paper, we first introduce an algorithm for estimating the visual contrast on a 3D mesh. We then perform a series of psychophysical experiments to study the effects of contrast sensitivity and contrast discrimination of the human visual system for the task of differentiating between two contrasts on a 3D mesh. The results of these experiments allow us to propose a perceptual model that is able to predict whether a change in local contrast on 3D mesh, induced by a local geometric distortion, is visible or not. Finally, we illustrate the utility of the proposed perceptual model in a number of applications: we compute the Just Noticeable Distortion (JND) profile for smooth-shaded 3D meshes and use the model to guide mesh processing algorithms.
Piecewise-planar Reconstruction of Multi-room Interiors with Arbitrary Wall Arrangements
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Mura, Claudio; Mattausch, Oliver; Pajarola, Renato; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Reconstructing the as-built architectural shape of building interiors has emerged in recent years as an important and challenging research problem. An effective approach must be able to faithfully capture the architectural structures and separate permanent components from clutter (e.g. furniture), while at the same time dealing with defects in the input data. For many applications, higher-level information on the environment is also required, in particular the shape of individual rooms. To solve this ill-posed problem, state-of-the-art methods assume constrained input environments with a 2.5D or, more restrictively, a Manhattan-world structure, which significantly restricts their applicability in real-world settings. We present a novel pipeline that allows to reconstruct general 3D interior architectures, significantly increasing the range of real-world architectures that can be reconstructed and labeled by any interior reconstruction method to date. Our method finds candidate permanent components by reasoning on a graph-based scene representation, then uses them to build a 3D linear cell complex that is partitioned into separate rooms through a multi-label energy minimization formulation. We demonstrate the effectiveness of our method by applying it to a variety of real-world and synthetic datasets and by comparing it to more specialized state-of-the-art approaches.
Direct Shape Optimization for Strengthening 3D Printable Objects
(The Eurographics Association and John Wiley & Sons Ltd., 2016) Zhou, Yahan; Kalogerakis, Evangelos; Wang, Rui; Grosse, Ian R.; Eitan Grinspun and Bernd Bickel and Yoshinori Dobashi
Recently there has been an increasing demand for software that can help designers create functional 3D objects with required physical strength. We introduce a generic and extensible method that directly optimizes a shape subject to physical and geometric constraints. Given an input shape, our method optimizes directly its input mesh representation until it can withstand specified external forces, while remaining similar to the original shape. Our method performs physics simulation and shape optimization together in a unified framework, where the physics simulator is an integral part of the optimizer. We employ geometric constraints to preserve surface details and shape symmetry, and adapt a second-order method with analytic gradients to improve convergence and computation time. Our method provides several advantages over previous work, including the ability to handle general shape deformations, preservation of surface details, and incorporation of user-defined constraints. We demonstrate the effectiveness of our method on a variety of printable 3D objects through detailed simulations as well as physical validations.

Browse

Browsing 35-Issue 7 by Issue Date

Results Per Page

Sort Options