VMV18

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https://diglib.eg.org/handle/10.2312/2632666

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Automatic Generation of Saliency-based Areas of Interest for the Visualization and Analysis of Eye-tracking Data
(The Eurographics Association, 2018) Fuhl, Wolfgang; Kuebler, Thomas; Santini, Thiago; Kasneci, Enkelejda; Beck, Fabian and Dachsbacher, Carsten and Sadlo, Filip
Areas of interest (AOIs) are a powerful basis for the analysis and visualization of eye-tracking data. They allow to relate eyetracking metrics to semantic stimulus regions and to perform further statistics. In this work, we propose a novel method for the automated generation of AOIs based on saliency maps. In contrast to existing methods from the state-of-the-art, which generate AOIs based on eye-tracking data, our method generates AOIs based solely on the stimulus saliency, mimicking thus our natural vision. This way, our method is not only independent of the eye-tracking data, but allows to work AOI-based even for complex stimuli, such as abstract art, where proper manual definition of AOIs is not trivial. For evaluation, we cross-validate support vector machine classifiers with the task of separating visual scanpaths of art experts from those of novices. The motivation for this evaluation is to use AOIs as projection functions and to evaluate their robustness on different feature spaces. A good AOI separation should result in different feature sets that enable a fast evaluation with a widely automated work-flow. The proposed method together with the data shown in this paper is available as part of the software EyeTrace [?] http://www.ti.unituebingen. de/Eyetrace.1751.0.html.
Compressed Bounding Volume Hierarchies for Efficient Ray Tracing of Disperse Hair
(The Eurographics Association, 2018) Martinek, Magdalena; Stamminger, Marc; Binder, Nikolaus; Keller, Alexander; Beck, Fabian and Dachsbacher, Carsten and Sadlo, Filip
Ray traced human hair is becoming more and more ubiquitous in photorealistic image synthesis. Despite hierarchical data structures for accelerated ray tracing, performance suffers from the bad separability inherent with ensembles of hair strands. We propose a compressed acceleration data structure that improves separability by adaptively subdividing hair fibers. Compression is achieved by storing quantized as well as oriented bounding boxes and an indexing scheme to specify curve segments instead of storing them. We trade memory for speed, as our approach may use more memory, however, in cases of highly curved hair we can double the number of traversed rays per second over prior work. With equal memory we still achieve a speed-up of up to 30%, with equal performance we can reduce memory by up to 30%.
Dynamic Environment Mapping for Augmented Reality Applications on Mobile Devices
(The Eurographics Association, 2018) Monroy, Rafael; Hudon, Matis; Smolic, Aljosa; Beck, Fabian and Dachsbacher, Carsten and Sadlo, Filip
Augmented Reality is a topic of foremost interest nowadays. Its main goal is to seamlessly blend virtual content in real-world scenes. Due to the lack of computational power in mobile devices, rendering a virtual object with high-quality, coherent appearance and in real-time, remains an area of active research. In this work, we present a novel pipeline that allows for coupled environment acquisition and virtual object rendering on a mobile device equipped with a depth sensor. While keeping human interaction to a minimum, our system can scan a real scene and project it onto a two-dimensional environment map containing RGB+Depth data. Furthermore, we define a set of criteria that allows for an adaptive update of the environment map to account for dynamic changes in the scene. Then, under the assumption of diffuse surfaces and distant illumination, our method exploits an analytic expression for the irradiance in terms of spherical harmonic coefficients, which leads to a very efficient rendering algorithm. We show that all the processes in our pipeline can be executed while maintaining an average frame rate of 31Hz on a mobile device.
Efficient Global Registration for Nominal/Actual Comparisons
(The Eurographics Association, 2018) Berkei, Sarah; Limper, Max; Hörr, Christian; Kuijper, Arjan; Beck, Fabian and Dachsbacher, Carsten and Sadlo, Filip
We investigate global registration methods for Nominal/Actual comparisons, using precise, high-resolution 3D scans. First we summarize existing approaches and requirements for this field of application. We then demonstrate that a basic RANSAC strategy, along with a slightly modified version of basic building blocks, can lead to a high global registration performance at moderate registration times. Specifically, we introduce a simple feedback loop that exploits the fast convergence of the ICP algorithm to efficiently speed up the search for a valid global alignment. Using the example of 3D printed parts and range images acquired by two different high-precision 3D scanners for quality control, we show that our method can be efficiently used for Nominal/Actual comparison. For this scenario, the proposed algorithm significantly outperforms the current state of the art, with regards to registration time and success rate.
A Fast and Efficient Semi-guided Algorithm for Flat Coloring Line-arts
(The Eurographics Association, 2018) Fourey, Sébastien; Tschumperlé, David; Revoy, David; Beck, Fabian and Dachsbacher, Carsten and Sadlo, Filip
We present a fast and efficient algorithm for the semi-supervised colorization of line-art images (e.g. hand-made cartoons), based on two successive steps: 1. A geometric analysis of the stroke contours, and their closing by splines/segments, and 2. A colorization step based on the filling of the corresponding connected components, either with random colors or by extrapolating user-defined color scribbles. Our processing technique performs image colorization with a similar quality as previous state of the arts algorithms, while having a lower algorithmic complexity, leading to more possible user interactivity.
Hierarchical Additive Poisson Disk Sampling
(The Eurographics Association, 2018) Dieckmann, Alexander; Klein, Reinhard; Beck, Fabian and Dachsbacher, Carsten and Sadlo, Filip
Generating samples of point clouds and meshes with blue noise characteristics is desirable for many applications in rendering and geometry processing. Working with laser-scanned or lidar point clouds, we usually find region with artifacts called scanlines and scan-edges. These regions are problematic for geometry processing applications, since it is not clear how many points should be selected to define a proper neighborhood. We present a method to construct a hierarchical additive poisson disk sampling from densely sampled point sets, which yield better point neighborhoods. It can be easily implemented using an octree data structure where each octree node contains a grid, called Modifiable Nested Octree [Sch14]. The generation of the sampling amounts to distributing the points over a hierarchy (octree) of resolution levels (grids) in a greedy manner. Propagating the distance constraint r through the hierarchy while drawing samples from the point set leads to a hierarchy of well distributed, random samplings. This ensures that in a disk with radius r, around a point, no other point upwards in the hierarchy is found. The sampling is additive in the sense that the union of points sets up to a certain hierarchy depth D is a poisson disk sampling. This makes it easy to select a resolution where the scan-artifacts have a lower impact on the processing result. The generated sampling can be made sensitive to surface features by a simple preprocessing step, yielding high quality low resolution poisson samplings of point clouds.
Interactive Interpolation of Metallic Effect Car Paints
(The Eurographics Association, 2018) Golla, Tim; Klein, Reinhard; Beck, Fabian and Dachsbacher, Carsten and Sadlo, Filip
Metallic car paints are visually complex materials that, among others effects, exhibit a view-dependent metallic sparkling, which is particularly difficult to recreate in computer graphics. While capturing real-world metallic paints is possible with specialized devices, creating these materials computationally poses a difficult problem. We present a method that allows for interactive interpolation between measured metallic automotive paints, which can be used to generate new realistic-looking metallic paint materials. By clustering the color information present in the measured bidirectional texture function (BTF) responsible for the metallic sparkling effect, we set up an optimal transport problem between metallic paints' appearances. The design of the problem facilitates efficiently finding a solution, based on which we generate a representation that allows for real-time generation of interpolated realistic materials. Interpolation happens smoothly, no flickering or other visual artifacts can be observed. The developed approach also enables to separately interpolate the larger-scale reflective properties, including the basic color hue, the local color hue, and the sparkling intensity of the metallic paint. Our method can be used intuitively in order to generate automotive paints with a novel appearance and explore the space of possible metallic paints spanned by given real-world measurements. The resulting materials are also well suited for real-time rendering in standard engines.
Painterly Rendering using Limited Paint Color Palettes
(The Eurographics Association, 2018) Lindemeier, Thomas; Gülzow, J. Marvin; Deussen, Oliver; Beck, Fabian and Dachsbacher, Carsten and Sadlo, Filip
We present a painterly rendering method for digital painting systems as well as visual feedback based painting machines that automatically extracts color palettes from images and computes mixture recipes for these from a set of real base paint colors based on the Kubelka-Munk theory. In addition, we present a new algorithm for distributing stroke candidates, which creates paintings with sharp details and contrasts. Our system is able to predict dry compositing of thinned or thick paint colors using an evaluation scheme based on example data collected from a calibration step and optical blending. We show results generated using a software stroke-based renderer and a painting machine.
Web-based Volume Rendering using Progressive Importance-based Data Transfer
(The Eurographics Association, 2018) Mwalongo, Finian; Krone, Michael; Reina, Guido; Ertl, Thomas; Beck, Fabian and Dachsbacher, Carsten and Sadlo, Filip
WebGL 2.0 makes it possible to implement efficient volume rendering that runs in browsers using 3D textures and complex fragment shaders. However, a typical bottleneck for web-based volume rendering is the size of the volumetric data sets. Transferring these data to the client for rendering can take a substantial amount of time, depending on the network speed. This can introduce latency that can in turn affect interactive rendering at the client. We address this challenge by introducing a multi-resolution bricked volume rendering, where data is transferred progressively. Similar to MIP-Mapping, the volume data is divided into multiple levels of detail. Each level of detail is broken down into bricks. The client requests the data brick by brick starting with the lowest resolution and renders each brick immediately as it is received. The 3D volume texture is updated as bricks with higher resolution are received asynchronously from the server. The advantages of this algorithm are that it reduces latency, the user can see at least a reduced-detail version of the data almost immediately, and the application always stays responsive while the data is updated. We also implemented a prioritization scheme for the bricks, where each brick can be assigned an importance value. Using this information, the client can request more important bricks first. Furthermore, we investigated the influence of data compression on the transfer and processing times.
WithTeeth: Denture Preview in Augmented Reality
(The Eurographics Association, 2018) Amirkhanov, Aleksandr; Amirkhanov, Artem; Bernhard, Matthias; Toth, Zsolt; Stiller, Sabine; Geier, Andreas; Gröller, Eduard; Mistelbauer, Gabriel; Beck, Fabian and Dachsbacher, Carsten and Sadlo, Filip
Dentures are prosthetic devices replacing missing or damaged teeth, often used for dental reconstruction. Dental reconstruction improves the functional state and aesthetic appearance of teeth. State-of-the-art methods used by dental technicians typically do not include the aesthetic analysis, which often leads to unsatisfactory results for patients. In this paper, we present a virtual mirror approach for a dental treatment preview in augmented reality. Different denture presets are visually evaluated and compared by switching them on the fly. Our main goals are to provide a virtual dental treatment preview to facilitate early feedback, and hence to build the confidence and trust of patients in the outcome. The workflow of our algorithm is as follows. First, the face is detected and 2D facial landmarks are extracted. Then, 3D pose estimation of upper and lower jaws is performed and high-quality 3D models of the upper and lower dentures are fitted. The fitting uses the occlusal plane angle as determined mnually by dental technicians. To provide a realistic impression of the virtual teeth, the dentures are rendered with motion blur. We demonstrate the robustness and visual quality of our approach by comparing the results of a webcam to a DSLR camera under natural, as well as controlled lighting conditions.

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Browsing VMV18 by Subject "Computing methodologies"

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