VMV16

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https://diglib.eg.org/handle/10.2312/2630932

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Singularities of the Inertial Flow Map Gradient
(The Eurographics Association, 2016) Günther, Tobias; Theisel, Holger; Matthias Hullin and Marc Stamminger and Tino Weinkauf
Inertial particles are finite-sized objects that are carried by flows, for example sand particles in air. In contrast to massless tracer particles, the trajectories of inertial particles can intersect in space-time. When this occurs, the inertial flow map gradient becomes singular. This has an impact on visualization concepts that require the flow map gradient to be invertible. An example are influence curves, which allow to move inertial particles backward in time and thereby avoid the numerically ill-posed inertial backward integration. In this paper, we show that singularities of the inertial flow map gradient can act as poles for influence curves, i.e., as structures that influence curves cannot cross. Influence curves thereby decay into disconnected pieces. We extract singularities in space-time and propose a simple approach to extract influence curves even when they are spatially disconnected. We demonstrate the extraction techniques and discuss the role of singularities in a number of 2D vector fields.
Fast Metric Acquisition with Mobile Devices
(The Eurographics Association, 2016) Garro, Valeria; Pintore, Giovanni; Ganovelli, Fabio; Gobbetti, Enrico; Scopigno, Roberto; Matthias Hullin and Marc Stamminger and Tino Weinkauf
We present a novel algorithm for fast metric reconstruction on mobile devices using a combination of image and inertial acceleration data. In contrast to previous approaches to this problem, our algorithm does not require a long acquisition time or intensive data processing and can be implemented entirely on common IMU-enabled tablet and smartphones. The method recovers real world units by comparing the acceleration values from the inertial sensors with the ones inferred from images. In order to cope with IMU signal noise, we propose a novel RANSAC-like strategy which helps to remove the outliers. We demonstrate the effectiveness and the accuracy of our method through an integrated mobile system returning point clouds in metric scale.
Artistic Composition for Painterly Rendering
(The Eurographics Association, 2016) Lindemeier, Thomas; Spicker, Marc; Deussen, Oliver; Matthias Hullin and Marc Stamminger and Tino Weinkauf
We present a technique for painterly renderings that follows a decomposition of the canvas into a set of regions and layers (coarse to fine). The regions reflect the spatial arrangement of the composition and the order in which the painting is to be created (typically back to front), and are produced in a way that new strokes only minimally paint over existing ones. Layers reflect the application of tools and are optimized for certain brush sizes. The number of strokes and colors that are needed to represent an input image are minimized by this decomposition, which is good for software, but essential for hardware-based rendering. Our method allows us to apply different painting styles to different regions as well as layers, and to create painterly renderings with more artistic freedom. We demonstrate our decomposition technique on images that are processed using hierarchical segmentation techniques.
Gloss Editing in Light Fields
(The Eurographics Association, 2016) Gryaditskaya, Yulia; Masia, Belen; Didyk, Piotr; Myszkowski, Karol; Seidel, Hans-Peter; Matthias Hullin and Marc Stamminger and Tino Weinkauf
With the improvement of both acquisition techniques, and computational and storage capabilities, we are witnessing an increasing presence of multidimensional scene representations. Two-dimensional, conventional images are gradually losing their hegemony, leaving room for novel formats. Among these, light fields are gaining importance, further propelled by the recent reappearance of virtual reality. Content generation is one of the stumbling blocks in this realm, and light fields are one of the main input sources of content. As their use becomes more common, a key challenge is the ability to edit or modify the appearance of the objects in the light field. This paper presents a method for manipulating the appearance of gloss in light fields. In particular, we propose a multidimensional filtering approach in which the specular highlights are filtered in the spatial and angular domains to target a desired increase of the material roughness. The filtering kernel is computed based on surface normals and view direction. Our technique generates angularly-coherent plausible edits in both synthetic and captured light fields.
A Phenomenological Approach to Integrating Gaussian Beam Properties and Speckle into a Physically-Based Renderer
(The Eurographics Association, 2016) Bergmann, Stephan; Mohammadikaji, Mahsa; Irgenfried, Stephan; Wörn, Heinz; Beyerer, Jürgen; Dachsbacher, Carsten; Matthias Hullin and Marc Stamminger and Tino Weinkauf
Coherent light exhibits properties that cannot be modeled by geometrical optics. Those properties include the limited focusability of light beams and the formation of speckle patterns when coherent light is scattered or reflected. We use existing physical models for these phenomena to mimic the behavior of Gaussian beams and the statistical properties of speckle patterns without performing a wave-optics simulation. These models have been integrated into a physically-based renderer with the intention of synthesizing sensor data for an optical inspection setup which uses a laser light source. This requires only local changes to the renderer and can also be used for real-time rendering.
Topological Triangle Sorting for Predefined Camera Paths
(The Eurographics Association, 2016) Weber, Christoph; Stamminger, Marc; Matthias Hullin and Marc Stamminger and Tino Weinkauf
We present a preprocessing pipeline for triangle meshes that topologically sorts all triangles for a given camera and scene animation in front-to-back or back-to-front order. This allows us to efficiently render a given animation without depth buffer, and to include transparency. We also remove non-contributing triangles, thus improving render time, especially when applying anti-aliasing. To this end we first record the visible triangles of a sequence of frames. For every frame we create a directed graph storing occlusion information. After a topological sort of this graph, all triangles are sorted properly. The contribution of this paper is the reduction of redundancy by merging the graphs of all frames. The result of our pipeline is a single sorted index buffer, over which we slide a window that yields sorted index buffers for each single frame. Circular dependencies are broken by placing duplicates of the affected triangles in the index buffer. Our sliding window then displays only frame specific triangles in their proper order. We conclude by demonstrating the benefits of removing invisible triangles and disabling the hardware visibility test.
Real-time Novel-view Synthesis for Volume Rendering Using a Piecewise-analytic Representation
(The Eurographics Association, 2016) Lochmann, Gerrit; Reinert, Bernhard; Buchacher, Arend; Ritschel, Tobias; Matthias Hullin and Marc Stamminger and Tino Weinkauf
Novel-view synthesis can be used to hide latency in a real-time remote rendering setup, to increase frame rate or to produce advanced visual effects such as depth-of-field or motion blur in volumes or stereo and light field imagery. Regrettably, existing real-time solutions are limited to opaque surfaces. Prior art has circumvented the challenge by making volumes opaque i. e., projecting the volume onto representative surfaces for reprojection, omitting correct volumetric effects. This paper proposes a layered image representation which is re-composed for the novel view with a special reconstruction filter. We propose a view-dependent approximation to the volume allowing to produce a typical novel view of 1024 1024 pixels in ca. 25 ms on a current GPU. At the heart of our approach is the idea to compress the complex view-dependent emission-absorption function along original view rays into a layered piecewise-analytic emission-absorption representation that can be efficiently ray-cast from a novel view. It does not assume opaque surfaces or approximate color and opacity, can be re-evaluated very efficiently, results in an image identical to the reference from the original view, has correct volumetric shading for novel views and works on a low and fixed number of layers per pixel that fits modern GPU architectures.
Scene Structure Inference through Scene Map Estimation
(The Eurographics Association, 2016) Hueting, Moos; Patraucean, Viorica; Ovsjanikov, Maks; Mitra, Niloy J.; Matthias Hullin and Marc Stamminger and Tino Weinkauf
Understanding indoor scene structure from a single RGB image is useful for a wide variety of applications ranging from the editing of scenes to the mining of statistics about space utilization. Most efforts in scene understanding focus on extraction of either dense information such as pixel-level depth or semantic labels, or very sparse information such as bounding boxes obtained through object detection. In this paper we propose the concept of a scene map, a coarse scene representation, which describes the locations of the objects present in the scene from a top-down view (i.e., as they are positioned on the floor), as well as a pipeline to extract such a map from a single RGB image. To this end, we use a synthetic rendering pipeline, which supplies an adapted CNN with virtually unlimited training data. We quantitatively evaluate our results, showing that we clearly outperform a dense baseline approach, and argue that scene maps provide a useful representation for abstract indoor scene understanding.
Finite Time Steady Vector Field Topology
(The Eurographics Association, 2016) Friederici, A.; Günther, T.; Rössl, C.; Theisel, H.; Oleg Lobachev
Vector Field Topology describes the asymptotic behavior of a flow in a vector field, i.e., the behavior for an integration time converging towards infinity. For some applications, a segmentation of the flow into areas of similar behavior for a finite integration time is desired. We introduce an approach for a finite-time segmentation of a steady vector field and equip the separatrices with additional information on how the separation evolves at each point with ongoing integration time. We analyze this behavior and its distribution along a separatrix, and provide a visual encoding for the 2D and 3D case. The result is an augmented topological skeleton. We demonstrate the approach on several artificial and simulated vector fields.
A Deferred Rendering Pipeline Including a Global Illumination Model for Atmospheric Scattering and Transparency
(The Eurographics Association, 2016) Heppner, S.; Dransfeld, M.; Domik, G.; Oleg Lobachev
Abstract This poster presents suitable global illumination models for atmospheric scattering in outdoor scenes combined with a deferred rendering pipeline which offers the possibility of rendering transparent objects. The use case is a HIL simulation for camera based ADAS tests that require a realistic rendering of outdoor scenes.
An Interactive Information Visualization Approach to Physically-Based Rendering
(The Eurographics Association, 2016) Simons, Gerard; Ament, Marco; Herholz, Sebastian; Dachsbacher, Carsten; Eisemann, Martin; Eisemann, Elmar; Matthias Hullin and Marc Stamminger and Tino Weinkauf
In this work, we present a novel information visualization tool to gain insight into the light transport in a physically-based rendering setting. The tool consists of a sampling-based data reduction technique, an extended interactive parallel coordinates plot providing an overview of the attributes linked to each light sample, 2D and 3D heat maps to represent different aspects of the rendering process, as well as a three-dimensional view to display and animate the light path transportation throughout the scene. We show several applications including differential light transport visualization for scene analysis, lighting and material optimization, reduction of rendering artifacts, and user-guided importance sampling.
VMV 2016: Frontmatter
(Eurographics Association, 2016) Matthias Hullin; Marc Stamminger; Tino Weinkauf;
3D Face Reconstruction with Silhouette Constraints
(The Eurographics Association, 2016) Hu, Qiyang; Zwicker, Matthias; Favaro, Paolo; Matthias Hullin and Marc Stamminger and Tino Weinkauf
In this paper we introduce silhouette constraints to improve the quality of unconstrained 3D face reconstruction. Previously, state of the art unconstrained 3D face reconstruction techniques relied solely on photometric consistency and matching sparse facial landmarks. We show that constraining the silhouettes of the 3D reconstruction to match silhouettes in the input images can further improve reconstruction quality. Our technique automatically detects silhouettes and iteratively matches silhouette points computed from the current 3D reconstruction with silhouettes in the input images. We demonstrate that our results improve on the previous state of the art in unconstrained 3D face reconstruction and that our additional constraints can easily be included in the iterative reconstruction at little additional cost.
A Framework for Interactive Realtime Image Editing
(The Eurographics Association, 2016) Hell, Benjamin; Mühlhausen, Moritz; Magnor, Marcus; Matthias Hullin and Marc Stamminger and Tino Weinkauf
We present a complete framework for interactive image editing with a focus on quickly obtaining results based on user input via brushstrokes. The goal is to show feedback to changing input in realtime while maintaining high quality output. We achieve this by extracting vital information in the form of local color clusters and a corresponding locally linear structure from the input image. With this information the problem of propagating any sort of features provided by user input can be executed conveniently and very efficiently. One of the major merits of our approach is that the locally linear structure does not impose any restrictions on the cluster structure. The fully automatically created structure essentially allows for a flexible scaling of the overall computational cost for propagating user edits. If needed, a more detailed output can be obtained by enforcing the creation of smaller clusters.
Metric Evolution Maps: Multidimensional Attribute-driven Exploration of Software Repositories
(The Eurographics Association, 2016) Silva, Renato Rodrigues Oliveira da; Vernier, Eduardo Faccin; Rauber, Paulo Eduardo; Comba, Joao L. D.; Minghim, Rosane; Telea, Alexandru C.; Matthias Hullin and Marc Stamminger and Tino Weinkauf
Understanding how software entities in a repository evolve over time is challenging, as an entity has many aspects that undergo such changes. We cast this problem in a multidimensional visualization context: First, we capture change by extracting quality metrics from all software entities in all revisions in a software repository, yielding a multidimensional time-dependent dataset. Next, we propose Metric Evolution Maps (MEMs), a new visual approach to create dynamic maps that show the similarity of entities in a revision and changes across revisions. We enrich MEMs with visual cues to show which metrics and metric values are key to formation of similar-entity patterns. Additionally, we show how entities change between revisions, and due to which metrics. We illustrate our approach by exploring changes in two real-world software repositories.
Structuring 3D Medial Skeletons: A Comparative Study
(The Eurographics Association, 2016) Delame, Thomas; Kustra, Jacek; Telea, Alexandru C.; Matthias Hullin and Marc Stamminger and Tino Weinkauf
Medial skeletons provide an effective alternative to boundary or volumetric representations for applications that focus on shape structure. This capability is provided by the skeletal structure, i.e., the curves and surfaces computed from centers of maximally inscribed balls by a process called structuration. Many several structuration methods exist, all having various challenges in terms of delivering a high-quality medial skeleton. This paper provides a first overview of existing structuration methods. We formally define the skeletal structure by giving its theoretical properties, and use these properties to propose quality criteria for structurations. We next review existing structuration methods and compare them using the established criteria. The obtained insights help both practitioners in choosing a suitable structuration method and researchers in further perfecting such methods.
PEEP: Perceptually Enhanced Exploration of Pictures
(The Eurographics Association, 2016) Agus, Marco; Villanueva, Alberto Jaspe; Pintore, Giovanni; Gobbetti, Enrico; Matthias Hullin and Marc Stamminger and Tino Weinkauf
We present a novel simple technique for rapidly creating and presenting interactive immersive 3D exploration experiences of 2D pictures and images of natural and artificial landscapes. Various application domains, ranging from virtual exploration of works of art to street navigation systems, can benefit from the approach. The method, dubbed PEEP, is motivated by the perceptual characteristics of the human visual system in interpreting perspective cues and detecting relative angles between lines. It applies to the common perspective images with zero or one vanishing points, and does not require the extraction of a precise geometric description of the scene. Taking as input a single image without other information, an automatic analysis technique fits a simple but perceptually consistent parametric 3D representation of the viewed space, which is used to drive an indirect constrained exploration method capable to provide the illusion of 3D exploration with realistic monocular (perspective and motion parallax) and binocular (stereo) depth cues. The effectiveness of the method is demonstrated on a variety of casual pictures and exploration configurations, including mobile devices.
Geodesic Iso-Curve Signature
(The Eurographics Association, 2016) Gehre, Anne; Bommes, David; Kobbelt, Leif; Matthias Hullin and Marc Stamminger and Tino Weinkauf
During the last decade a set of surface descriptors have been presented describing local surface features. Recent approaches [COO15] have shown that augmenting local descriptors with topological information improves the correspondence and segmentation quality. In this paper we build upon the work of Tevs et al. [TBW 11] and Sun and Abidi [SA01] by presenting a surface descriptor which captures both local surface properties and topological features of 3D objects. We present experiments on shape repositories that are provided with ground-truth correspondences (FAUST, SCAPE, TOSCA) which show that this descriptor outperforms current local surface descriptors.
Reflection Separation in Light Fields based on Sparse Coding and Specular Flow
(The Eurographics Association, 2016) Sulc, Antonin; Alperovich, Anna; Marniok, Nico; Goldluecke, Bastian; Matthias Hullin and Marc Stamminger and Tino Weinkauf
We present a method to separate a dichromatic reflection component from diffuse object colors for the set of rays in a 4D light field such that the separation is consistent across all subaperture views. The separation model is based on explaining the observed light field as a sparse linear combination of a constant-color specular term and a small finite set of albedos. Consistency across the light field is achieved by embedding the ray-wise separation into a global optimization framework. On each individual epipolar plane image (EPI), the diffuse coefficients need to be constant along lines which are the projections of the same scene point, while the specular coefficient needs to be constant along the direction of the specular flow within the epipolar volume. We handle both constraints with depth-dependent anisotropic regularizers, and demonstrate promising performance on a number of real-world light fields captured with a Lytro Illum plenoptic camera.
Variable Length Coding for GPU-Based Direct Volume Rendering
(The Eurographics Association, 2016) Guthe, Stefan; Goesele, Michael; Matthias Hullin and Marc Stamminger and Tino Weinkauf
The sheer size of volume data sampled in a regular grid requires efficient lossless and lossy compression algorithms that allow for on-the-fly decompression during rendering. While all hardware assisted approaches are based on fixed bit rate block truncation coding, they suffer from degradation in regions of high variation while wasting space in homogeneous areas. On the other hand, vector quantization approaches using texture hardware achieve an even distribution of error in the entire volume at the cost of storing overlapping blocks or bricks. However, these approaches suffer from severe blocking artifacts that need to be smoothed over during rendering. In contrast to existing approaches, we propose to build a lossy compression scheme on top of a state-of-the-art lossless compression approach built on non-overlapping bricks by combining it with straight forward vector quantization. Due to efficient caching and load balancing, the rendering performance of our approach improves with the compression rate and can achieve interactive to real-time frame rates even at full HD resolution.

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