EG2012

Permanent URI for this community

https://diglib.eg.org/handle/10.2312/292

Browse

Now showing 1 - 20 of 138

Fast Grasp Synthesis for Various Shaped Objects
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Kyota, Fumihito; Saito, Suguru; P. Cignoni and T. Ertl
Human-like grasp planning is difficult because a human hand has a high number of degrees of freedom, and there are many grasping styles depending on the shape of an object and purpose. We propose a fast grasp synthesis system which enables a user to choose the desired grasping styles from a set of grasp types in a human grasp taxonomy. Given a 3D model of an object, our system detects graspable positions and generates grasping hand postures in every applicable grasp types in the grasp taxonomy for each grasping position. Hand postures are generated separately for each digit, and hand alignment is then refined iteratively. A user can also specify the grasping position by moving the cursor onto object surface, as well as grasp type. The generated hand postures are shown as a table of thumbnail images, and the user can select the grasping hand posture by clicking on one of those postures. Our system enables interactive generation of various grasping hand postures in real time.
SimpleFlow: A Non-iterative, Sublinear Optical Flow Algorithm
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Tao, Michael; Bai, Jiamin; Kohli, Pushmeet; Paris, Sylvain; P. Cignoni and T. Ertl
Optical flow is a critical component of video editing applications, e.g. for tasks such as object tracking, segmentation, and selection. In this paper, we propose an optical flow algorithm called SimpleFlow whose running times increase sublinearly in the number of pixels. Central to our approach is a probabilistic representation of the motion flow that is computed using only local evidence and without resorting to global optimization. To estimate the flow in image regions where the motion is smooth, we use a sparse set of samples only, thereby avoiding the expensive computation inherent in traditional dense algorithms. We show that our results can be used as is for a variety of video editing tasks. For applications where accuracy is paramount, we use our result to bootstrap a global optimization. This significantly reduces the running times of such methods without sacrificing accuracy. We also demonstrate that the SimpleFlow algorithm can process HD and 4K footage in reasonable times.
Iterative Image Warping
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Bowles, Huw; Mitchell, Kenny; Sumner, Robert W.; Moore, Jeremy; Gross, Markus; P. Cignoni and T. Ertl
Animated image sequences often exhibit a large amount of inter-frame coherence which standard rendering algorithms and pipelines are ill-equipped to exploit, limiting their efficiency. To address this inefficiency we transfer rendering results across frames using a novel image warping algorithm based on fixed point iteration. We analyze the behavior of the iteration and describe two alternative algorithms designed to suit different performance requirements. Further, to demonstrate the versatility of our approach we apply it to a number of spatio-temporal rendering problems including 30-to-60Hz frame upsampling, stereoscopic 3D conversion, defocus and motion blur. Finally we compare our approach against existing image warping methods and demonstrate a significant performance improvement.
Repetition Maximization based Texture Rectification
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Aiger, Dror; Cohen-Or, Daniel; Mitra, Niloy J.; P. Cignoni and T. Ertl
Many photographs are taken in perspective. Techniques for rectifying resulting perspective distortions typically rely on the existence of parallel lines in the scene. In scenarios where such parallel lines are hard to automatically extract or manually annotate, the unwarping process remains a challenge. In this paper, we introduce an automatic algorithm to rectifying images containing textures of repeated elements lying on an unknown plane. We unwrap the input by maximizing for image self-similarity over the space of homography transformations. We map a set of detected regional descriptors to surfaces in a transformation space, compute the intersection points among triplets of such surfaces, and then use consensus among the projected intersection points to extract the correcting transform. Our algorithm is global, robust, and does not require explicit or accurate detection of similar elements. We evaluate our method on a variety of challenging textures and images. The rectified outputs are directly useful for various tasks including texture synthesis, image completion, etc.
Interactive Self-Organizing Windows
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Steinberger, Markus; Waldner, Manuela; Schmalstieg, Dieter; P. Cignoni and T. Ertl
In this paper, we present the design and implementation of a dynamic window management technique that changes the perception of windows as fixed-sized rectangles. The primary goal of self-organizing windows is to automatically display the most relevant information for a user's current activity, which removes the burden of organizing and arranging windows from the user. We analyze the image-based representation of each window and identify coherent pieces of information. The windows are then automatically moved, scaled and composed in a contentaware manner to fit the most relevant information into the limited area of the screen. During the design process, we consider findings from previous experiments and show how users can benefit from our system. We also describe how the immense processing power of current graphics processing units can be exploited to build an interactive system that finds an optimal solution within the complex design space of all possible window transformations in real time.
Realistic Following Behaviors for Crowd Simulation
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Lemercier, Samuel; Jelic, Asja; Kulpa, Richard; Hua, Jiale; Fehrenbach, Jérôme; Degond, Pierre; Appert-Rolland, Cécile; Donikian, Stéphane; Pettré, Julien; P. Cignoni and T. Ertl
While walking through a crowd, a pedestrian experiences a large number of interactions with his neighbors. The nature of these interactions is varied, and it has been observed that macroscopic phenomena emerge from the combination of these local interactions. Crowd models have hitherto considered collision avoidance as the unique type of interactions between individuals, few have considered walking in groups. By contrast, our paper focuses on interactions due to the following behaviors of pedestrians. Following is frequently observed when people walk in corridors or when they queue. Typical macroscopic stop-and-go waves emerge under such traffic conditions. Our contributions are, first, an experimental study on following behaviors, second, a numerical model for simulating such interactions, and third, its calibration, evaluation and applications. Through an experimental approach, we elaborate and calibrate a model from microscopic analysis of real kinematics data collected during experiments. We carefully evaluate our model both at the microscopic and the macroscopic levels. We also demonstrate our approach on applications where following interactions are prominent.
Stochastic Progressive Photon Mapping for Dynamic Scenes
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Weiss, Maayan; Grosch, Thorsten; P. Cignoni and T. Ertl
Stochastic Progressive Photon Mapping (SPPM) is a method to simulate consistent global illumination. It is especially useful for complicated light paths like caustics seen through a glass surface. Up to now, SPPM can only be applied to a static scene and noise-free images require hours to compute. Our approach is to extend this method to dynamic scenes (DSPPM) for an efficient simulation of animated objects and materials. We identify both hit point and photon information that can be re-used for the pixel statistics of multiple frames. In comparison to an SPPM simulation performed for each frame, we achieve a 1.96 - 9.53 speedup in our test scenes without changing correctness or simulation quality.
Interactive Multi-perspective Imagery from Photos and Videos
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Lieng, Henrik; Tompkin, James; Kautz, Jan; P. Cignoni and T. Ertl
Photographs usually show a scene from a single perspective. However, as commonly seen in art, scenes and objects can be visualized from multiple perspectives. Making such images manually is time consuming and tedious. We propose a novel system for designing multi-perspective images and videos. First, the images in the input sequence are aligned using structure from motion. This enables us to track feature points across the sequence. Second, the user chooses portal polygons in a target image into which different perspectives are to be embedded. The corresponding image regions from the other images are then copied into these portals. Due to the tracking feature and automatic warping, this approach is considerably faster than current tools. We explore a wide range of artistic applications using our system with image and video data, such as looking around corners and up and down stair cases, recursive multi-perspective imaging, cubism and panoramas.
Black is Green: Adaptive Color Transformation For Reduced Ink Usage
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Shapira, Lior; Oicherman, Boris; P. Cignoni and T. Ertl
A vast majority of color transformations applied to an image in the digital press industry are static and precalculated. In order to achieve the best quality on a wide variety of different images, these transformations tend to be highly conservative with respect to the use of black ink. This results in excessive use of inks, which has a negative economic and environmental impact. We present a method for dynamic computation of color transformation based on image content, with the aim to reduce ink usage. We analyze the image, and predict areas in which quality artifacts that may result from such a reduction will be masked by the image content. These areas include detailed textures, noisy areas and structure. We then replace the image CMYK values by a new combination with increased black. Our algorithm ensures negligible color shifts in the resulting image, and no visible reduction in quality. We achieve an average of over 10% ink savings.
Procedural Interpolation of Historical City Maps
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Krecklau, Lars; Manthei, Christopher; Kobbelt, Leif; P. Cignoni and T. Ertl
We propose a novel approach for the temporal interpolation of city maps. The input to our algorithm is a sparse set of historical city maps plus optional additional knowledge about construction or destruction events. The output is a fast forward animation of the city map development where roads and buildings are constructed and destroyed over time in order to match the sparse historical facts and to look plausible where no precise facts are available. A smooth transition between any real-world data could be interesting for educational purposes, because our system conveys an intuition of the city development. The insertion of data, like when and where a certain building or road existed, is efficiently performed by an intuitive graphical user interface. Our system collects all this information into a global dependency graph of events. By propagating time intervals through the dependency graph we can automatically derive the earliest and latest possible date for each event which are guaranteeing temporal as well as geographical consistency (e.g. buildings can only appear along roads that have been constructed before). During the simulation of the city development, events are scheduled according to a score function that rates the plausibility of the development (e.g. cities grow along major roads). Finally, the events are properly distributed over time to control the dynamics of the city development. Based on the city map animation we create a procedural city model in order to render a 3D animation of the city development over decades.
A Cell-Based Light Interaction Model for Human Blood
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Yim, Daniel; Baranoski, Gladimir V. G.; Kimmel, Brad W.; Chen, T. Francis; Miranda, Erik; P. Cignoni and T. Ertl
The development of predictive appearance models for organic tissues is a challenging task due to the inherent complexity of these materials. In this paper, we closely examine the biophysical processes responsible for the appearance attributes of whole blood, one the most fundamental of these materials. We describe a new appearance model that simulates the mechanisms of light propagation and absorption within the cellular and fluid portions of this specialized tissue. The proposed model employs a comprehensive, and yet flexible first principles approach based on the morphological, optical and biochemical properties of blood cells. This approach allows for environment driven changes in the cells' anatomy and orientation to be appropriately included into the light transport simulations. The correctness and predictive capabilities of the proposed model are quantitatively and qualitatively evaluated through comparisons of modeled results with actual measured data and experimental observations reported in the scientific literature. Its incorporation into rendering systems is illustrated through images of blood samples depicting appearance variations controlled by physiologically meaningful parameters. Besides the contributions to the modeling of material appearance, the research presented in this paper is also expected to have applications in a wide range of biomedical areas, from optical diagnostics to the visualization and noninvasive imaging of blood-perfused tissues.
Interactive Editing of GigaSample Terrain Fields
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Treib, Marc; Reichl, Florian; Auer, Stefan; Westermann, Rüdiger; P. Cignoni and T. Ertl
Previous terrain rendering approaches have addressed the aspect of data compression and fast decoding for rendering, but applications where the terrain is repeatedly modified and needs to be buffered on disk have not been considered so far. Such applications require both decoding and encoding to be faster than disk transfer. We present a novel approach for editing gigasample terrain fields at interactive rates and high quality. To achieve high decoding and encoding throughput, we employ a compression scheme for height and pixel maps based on a sparse wavelet representation. On recent GPUs it can encode and decode up to 270 and 730 MPix/s of color data, respectively, at compression rates and quality superior to JPEG, and it achieves more than twice these rates for lossless height field compression. The construction and rendering of a height field triangulation is avoided by using GPU ray-casting directly on the regular grid underlying the compression scheme. We show the efficiency of our method for interactive editing and continuous level-of-detail rendering of terrain fields comprised of several hundreds of gigasamples.
NoRM: No-Reference Image Quality Metric for Realistic Image Synthesis
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Herzog, Robert; Cadík, Martin; Aydin, Tunç O.; Kim, Kwang In; Myszkowski, Karol; Seidel, Hans-Peter; P. Cignoni and T. Ertl
Synthetically generating images and video frames of complex 3D scenes using some photo-realistic rendering software is often prone to artifacts and requires expert knowledge to tune the parameters. The manual work required for detecting and preventing artifacts can be automated through objective quality evaluation of synthetic images. Most practical objective quality assessment methods of natural images rely on a ground-truth reference, which is often not available in rendering applications. While general purpose no-reference image quality assessment is a difficult problem, we show in a subjective study that the performance of a dedicated no-reference metric as presented in this paper can match the state-of-the-art metrics that do require a reference. This level of predictive power is achieved exploiting information about the underlying synthetic scene (e.g., 3D surfaces, textures) instead of merely considering color, and training our learning framework with typical rendering artifacts. We show that our method successfully detects various non-trivial types of artifacts such as noise and clamping bias due to insufficient virtual point light sources, and shadow map discretization artifacts. We also briefly discuss an inpainting method for automatic correction of detected artifacts.
Data-Driven Estimation of Cloth Simulation Models
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Miguel, Eder; Bradley, Derek; Thomaszewski, Bernhard; Bickel, Bernd; Matusik, Wojciech; Otaduy, Miguel A.; Marschner, Steve; P. Cignoni and T. Ertl
Progress in cloth simulation for computer animation and apparel design has led to a multitude of deformation models, each with its own way of relating geometry, deformation, and forces. As simulators improve, differences between these models become more important, but it is difficult to choose a model and a set of parameters to match a given real material simply by looking at simulation results. This paper provides measurement and fitting methods that allow nonlinear models to be fit to the observed deformation of a particular cloth sample. Unlike standard textile testing, our system measures complex 3D deformations of a sheet of cloth, not just one-dimensional force-displacement curves, so it works under a wider range of deformation conditions. The fitted models are then evaluated by comparison to measured deformations with motions very different from those used for fitting.
Data-Driven Object Manipulation in Images
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Goldberg, Chen; Chen, Tao; Zhang, Fang-Lue; Shamir, Ariel; Hu, Shi-Min; P. Cignoni and T. Ertl
We present a framework for interactively manipulating objects in a photograph using related objects obtained from internet images. Given an image, the user selects an object to modify, and provides keywords to describe it. Objects with a similar shape are retrieved and segmented from online images matching the keywords, and deformed to correspond with the selected object. By matching the candidate object and adjusting manipulation parameters, our method appropriately modifies candidate objects and composites them into the scene. Supported manipulations include transferring texture, color and shape from the matched object to the target in a seamless manner. We demonstrate the versatility of our framework using several inputs of varying complexity, for object completion, augmentation, replacement and revealing. Our results are evaluated using a user study.
Computational Design of Rubber Balloons
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Skouras, Mélina; Thomaszewski, Bernhard; Bickel, Bernd; Gross, Markus; P. Cignoni and T. Ertl
This paper presents an automatic process for fabrication-oriented design of custom-shaped rubber balloons. We cast computational balloon design as an inverse problem: given a target shape, we compute an optimal balloon that, when inflated, approximates the target as closely as possible. To solve this problem numerically, we propose a novel physics-driven shape optimization method, which combines physical simulation of inflatable elastic membranes with a dedicated constrained optimization algorithm. We validate our approach by fabricating balloons designed with our method and comparing their inflated shapes to the results predicted by simulation. An extensive set of manufactured sample balloons demonstrates the shape diversity that can be achieved by our method.
Manufacturing Layered Attenuators for Multiple Prescribed Shadow Images
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Baran, Ilya; Keller, Philipp; Bradley, Derek; Coros, Stelian; Jarosz, Wojciech; Nowrouzezahrai, Derek; Gross, Markus; P. Cignoni and T. Ertl
We present a practical and inexpensive method for creating physical objects that cast different color shadow images when illuminated by prescribed lighting configurations. The input to our system is a number of lighting configurations and corresponding desired shadow images. Our approach computes attenuation masks, which are then printed on transparent materials and stacked to form a single multi-layer attenuator. When illuminated with the input lighting configurations, this multi-layer attenuator casts the prescribed color shadow images. Alternatively, our method can compute layers so that their permutations produce different prescribed shadow images under fixed lighting. Each multi-layer attenuator is quick and inexpensive to produce, can generate multiple full-color shadows, and can be designed to respond to different types of natural or synthetic lighting setups. We illustrate the effectiveness of our multi-layer attenuators in simulation and in reality, with the sun as a light source.
Interaction Retrieval by Spacetime Proximity Graphs
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Tang, Jeff K. T.; Chan, Jacky C. P.; Leung, Howard; Komura, Taku; P. Cignoni and T. Ertl
In this paper, we propose a new method to index and retrieve animation scenes in which multiple characters closely interact with one another. Such a technique can be an important tool for animators when they want to automatically extract the desired scene from a large database of animation sequence. Existing methods for single character movements do not scale well for multiple characters as they do not take into account the interaction of different body parts. In this paper, we propose a new distance function that computes the similarity of twocharacter interations using the spatial relationship of the body parts. For each interaction, we produce a timevarying graph structure based on the proximity of different joints, and compute the similarity of interactions by comparing the topology and Laplacian coordinates of the time-varying graph. Experimental results show that the proposed method outperforms previous methods which are based on the kinematics of individual characters. The top retrieved samples are found similar in high level semantics while containing style variations.
Procedural Generation of Parcels in Urban Modeling
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Vanegas, Carlos A.; Kelly, Tom; Weber, Basil; Halatsch, Jan; Aliaga, Daniel G.; Müller, Pascal; P. Cignoni and T. Ertl
We present a method for interactive procedural generation of parcels within the urban modeling pipeline. Our approach performs a partitioning of the interior of city blocks using user-specified subdivision attributes and style parameters. Moreover, our method is both robust and persistent in the sense of being able to map individual parcels from before an edit operation to after an edit operation - this enables transferring most, if not all, customizations despite small to large-scale interactive editing operations. The guidelines guarantee that the resulting subdivisions are functionally and geometrically plausible for subsequent building modeling and construction. Our results include visual and statistical comparisons that demonstrate how the parcel configurations created by our method can closely resemble those found in real-world cities of a large variety of styles. By directly addressing the block subdivision problem, we intend to increase the editability and realism of the urban modeling pipeline and to become a standard in parcel generation for future urban modeling methods.
Generalized Swept Mid-structure for Polygonal Models
(The Eurographics Association and John Wiley and Sons Ltd., 2012) Martin, Tobias; Chen, Guoning; Musuvathy, Suraj; Cohen, Elaine; Hansen, Charles; P. Cignoni and T. Ertl
We introduce a novel mid-structure called the generalized swept mid-structure (GSM) of a closed polygonal shape, and a framework to compute it. The GSM contains both curve and surface elements and has consistent sheet-by-sheet topology, versus triangle-by-triangle topology produced by other mid-structure methods. To obtain this structure, a harmonic function, defined on the volume that is enclosed by the surface, is used to decompose the volume into a set of slices. A technique for computing the 1D mid-structures of these slices is introduced. The mid-structures of adjacent slices are then iteratively matched through a boundary similarity computation and triangulated to form the GSM. This structure respects the topology of the input surface model is a hybrid mid-structure representation. The construction and topology of the GSM allows for local and global simplification, used in further applications such as parameterization, volumetric mesh generation and medical applications.

Browse

Browsing EG2012 by Issue Date

Results Per Page

Sort Options