VMV10

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/1014

Browse

Now showing 1 - 20 of 43

3D Curve-Skeleton Extraction Algorithm Using a Pseudo-Normal Vector Field
(The Eurographics Association, 2010) Pantuwong, Natapon; Sugimoto, Masanori; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
A curve skeleton is a line representation of a 3D object. It is useful in many applications, such as animation, shape matching or scientific analysis. The method described in this paper extracts a curve skeleton from the vector field which is created inside the 3D object. The topology of the vector field is analyzed to obtain the curve skeleton. In contrast with previous methods, the vector field is calculated using a pseudo-normal vector. Furthermore, by using the proposed skeleton-growing method, the vector field topology need not be computed for every voxel. Therefore, the proposed approach requires significantly less computation compared with previous vector field-based approaches, while still capturing all important parts of 3D object. The proposed method is very useful for any applications, especially real-time applications such as quick animation production and prototyping of graphical systems.
Adaptive Image-space Stereo View Synthesis
(The Eurographics Association, 2010) Didyk, Piotr; Ritschel, Tobias; Eisemann, Elmar; Myszkowski, Karol; Seidel, Hans-Peter; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Stereo vision is becoming increasingly popular in feature films, visualization and interactive applications such as computer games. However, computation costs are doubled when rendering an individual image for each eye. In this work, we propose to only render a single image, together with a depth buffer and use image-based techniques to generate two individual images for the left and right eye. The resulting method computes a high-quality stereo pair for roughly half the cost of the traditional methods. We achieve this result via an adaptive-grid warping that also involves information from previous frames to avoid artifacts.
Analysis of Structural Dependencies for the Automatic Visual Inspection of Wire Ropes
(The Eurographics Association, 2010) Haase, Daniel; Wacker, Esther-Sabrina; Schukat-Talamazzini, Ernst Günter; Denzler, Joachim; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Automatic visual inspection is an arising field of research. Especially in security relevant applications, an automation of the inspection process would be a great benefit. For wire ropes, a first step is the acquisition of the curved surface with several cameras located all around the rope. Because most of the visible defects in such a rope are very inconspicuous, an automatic defect detection is a very challenging problem. As in general there is a lack of defective training data, most of the presented ideas for automatic rope inspection are embedded in a one-class classification framework. However, none of these methods makes use of the context information which results from the fact that all camera views image the same rope. In contrast to an individual analysis of each camera view, this work proposes the simultaneous analysis of all available camera views with the help of a vector autoregressive model. Moreover, various dependency analysis methods are used to give consideration to the regular rope structure and to deal with the high dimensionality of the problem. These dependencies are then used as constraints for the vector autoregressive model, which results in a sparse but powerful detection system. The proposed method is evaluated by using real wire rope data and the conducted experiments show that our approach clearly outperforms all previously presented methods.
Application of Tensor Approximation to Multiscale Volume Feature Representations
(The Eurographics Association, 2010) Suter, Susanne K.; Zollikofer, Christoph P. E.; Pajarola, Renato; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Advanced 3D microstructural analysis in natural sciences and engineering depends ever more on modern data acquisition and imaging technologies such as micro-computed or synchrotron tomography and interactive visualization. The acquired volume data sets are not only of high-resolution but in particular exhibit complex spatial structures at different levels of scale (e.g. variable spatial expression of multiscale periodic growth structures in tooth enamel). Such highly structured volume data sets represent a tough challenge to be analyzed and explored by means of interactive visualization due to the amount of raw volume data to be processed and filtered for the desired features. As an approach to address this bottleneck by multiscale feature preserving data reduction, we propose higher-order tensor approximations (TAs). We demonstrate the power of TA to represent, and highlight the structural features in volume data. We visually and quantitatively show that TA yields high data reduction and that TA preserves volume features at multiple scales.
CALTag: High Precision Fiducial Markers for Camera Calibration
(The Eurographics Association, 2010) Atcheson, Bradley; Heide, Felix; Heidrich, Wolfgang; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
We present a self-identifying marker pattern for camera calibration, together with the associated detection algorithm. The pattern is designed to support high-precision, fully-automatic localization of calibration points, as well as identification of individual markers in the presence of significant occlusions, uneven illumination, and observations under extremely acute angles. The detection algorithm is efficient and free of parameters. After calibration we obtain reprojection errors significantly lower than with state-of-the art self-identifying reference patterns.
Coherent Background Video Inpainting through Kalman Smoothing along Trajectories
(The Eurographics Association, 2010) Bugeau, Aurélie; Gargallo, Paul; D'Hondt, Olivier; Hervieu, Alexandre; Papadakis, Nicolas; Caselles, Vicent; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Video inpainting consists in recovering the missing or corrupted parts of an image sequence so that the reconstructed sequence looks natural. For each frame, the reconstruction has to be spatially coherent with the rest of the image and temporally with respect to the reconstructions of adjacent frames. Most of existing methods only focus on inpainting foreground objects moving with a periodic motion and consider that the background is almost static. In this paper we address the problem of background inpainting and propose a method that handles dynamic background (illumination changes, moving camera, dynamic textures...). The algorithm starts by applying an image inpainting technique to each frame of the sequence and then temporally smoothes these reconstructions through Kalman smoothing along the estimated trajectories of the unknown points. The computation of the trajectories relies on the estimation of forward and backward dense optical flow fields. Several experiments and comparisons demonstrate the performance of the proposed approach.
Continuous Deformations of Implicit Surfaces
(The Eurographics Association, 2010) Esturo, Janick Martinez; Rössl, Christian; Theisel, Holger; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
We introduce an approach for the continuous deformation of implicit surfaces which considers properties of all isosurfaces of a volume data set simultaneously. This is achieved by integrating divergence-free vector fields which is carried out by an efficient backward Lagrangian integration scheme. Our deformation guarantees volume preservation inside each isosurface as well as the preservation of continuity and topology of every isosurface. For visualization and interaction, we offer a real-time mode that allows interactive working on the resolution of the underlying volumetric grid as well as a grid resolution independent mode offering exact extraction of arbitrary isosurfaces. We apply the approach to the deformation of measured volume data sets as well as to the design of complex implicit shapes with a simple pre-defined topology.
Convex Relaxation for Grain Segmentation at Atomic Scale
(The Eurographics Association, 2010) Boerdgen, Markus; Berkels, Benjamin; Rumpf, Martin; Cremers, Daniel; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Grains are material regions with different lattice orientation at atomic scale. They can be resolved on material surfaces with recent image acquisition technology. Simultaneously, new microscopic simulation tools allow to study mechanical models of grain structures. The robust and reliable identification and visualization of grain boundaries - in images both from simulation and from experiments - is of central importance in the field of material surface analysis. In this work, we compare a variety of variational approaches for grain boundary estimation from microscopy and simulation images. In particular, we show that grain boundary estimation can be solved by means of recently introduced convex relaxation techniques. These techniques allow to compute global solutions or solutions within a known bound of the optimum. Moreover, experimental results both on simulated and on transmission electron microscopy images confirm that the convex relaxation techniques provide significant improvements of the estimated grain boundaries over previously employed multiphase level set formulations.
Cost-effective Feature Enhancement for Volume Datasets
(The Eurographics Association, 2010) Díaz, Jose; Marco, Jordi; Vázquez, Pere-Pau; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Volume models often show high complexity. Local details and overall shape may sometimes be difficult to perceive. Unsharp masking techniques improve the perception of those small features by increasing the local contrast. In this paper we present a simple and fast method for feature enhancement based on 3D mipmaps. In contrast to other approaches, in addition to increasing luminance on the feature details, we also darken the valleys of the volume thus increasing local contrast and making neighboring details more visible. Our approach is fast and simple, with small memory requirements thanks to the use of 3D mipmaps. We also propose a color selection strategy, based on harmonic colors, that further enhances the salient features without abrupt or uncomfortable color changes.
DC-Splines: Revisiting the Trilinear Interpolation on the Body-Centered Cubic Lattice
(The Eurographics Association, 2010) Domonkos, Balázs; Csébfalvi, Balázs; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
In this paper, we thoroughly study a trilinear interpolation scheme previously proposed for the Body-Centered Cubic (BCC) lattice. We think that, up to now, this technique has not received the attention that it deserves. By a frequency-domain analysis we show that it can isotropically suppress those aliasing spectra that contribute most to the postaliasing effect. Furthermore, we present an efficient GPU implementation, which requires only six trilinear texture fetches per sample. Overall, we demonstrate that the trilinear interpolation on the BCC lattice is competitive to the linear box-spline interpolation in terms of both efficiency and image quality. As a generalization to higher-order reconstruction, we introduce DC-splines that are constructed by convolving a Discrete filter with a Continuous filter, and easy to adapt to the Face-Centered Cubic (FCC) lattice as well.
Direct Image Registration without Region of Interest
(The Eurographics Association, 2010) Brunet, Florent; Bartoli, Adrien; Navab, Nassir; Malgouyres, Rémy; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Standard direct image registration consists in estimating the geometric warp between a source and a target images by maximizing the photometric similarity for the pixels of a Region of Interest (ROI). The ROI must be included in the real overlap between the images otherwise standard registration algorithms fail. Determining a proper ROI is a hard 'chicken-and-egg' problem since the overlap is only known after a successful registration. Almost all algorithms in the literature consider that the ROI is given. This is generally either inconvenient or unreliable. In this paper we propose a new method that registers two images without using a ROI. The key idea of our method is to consider the off-target pixels as outliers. We define the off-target pixels as those pixels of the source image mapped outside the target image by the current warp. We use the classical robust M-estimation framework to handle both the off-target pixels and the usual outliers caused, for instance, by occlusions. With our formulation, the true image overlap is defined as the set of inliers. Experiments on synthetic and real data with the homography and Free-Form Deformation show that our method outperforms standard approaches in terms of accuracy and robustness while precisely retrieving the overlap in the source and target images.
Direct Resampling for Isotropic Surface Remeshing
(The Eurographics Association, 2010) Fuhrmann, Simon; Ackermann, Jens; Kalbe, Thomas; Goesele, Michael; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
We present a feature-sensitive remeshing algorithm for relaxation-based methods. The first stage of the algorithm creates a new mesh from scratch by resampling the reference mesh with an exact vertex budget with either uniform or non-uniform vertex distribution according to a density function. The newly introduced samples on the mesh surface are triangulated directly in 3D by constructing a mutual tessellation. The second stage of the algorithm optimizes the positions of the mesh vertices by building a weighted centroidal Voronoi tessellation to obtain a precise isotropic placement of the samples. We achieve isotropy by employing Lloyd's relaxation method, but other relaxation schemes are applicable. The proposed algorithm handles diverse meshes of arbitrary genus and guarantees that the remeshed model has the same topology as the input mesh. The density function can be defined by the user or derived automatically from the estimated curvature at the mesh vertices. A subset of the mesh edges may be tagged as sharp features to preserve the characteristic appearance of technical models. The new method can be applied to large meshes and produces results faster than previously achievable.
Dynamic Focus + Context for Volume Rendering
(The Eurographics Association, 2010) Sikachev, Peter; Rautek, Peter; Bruckner, Stefan; Gröller, M. Eduard; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Interactive visualization is widely used in many applications for efficient representation of complex data. Many techniques make use of the focus+context approach in a static manner. These techniques do not fully make use of the interaction semantics. In this paper we present a dynamic focus+context approach that highlights salient features during user interaction. We explore rotation, panning, and zooming interaction semantics and propose several methods of changing visual representations, based on a suggested engagement-estimation method. We use DVR-MIP interpolation and a radial opacity-change approach, exploring rotation, panning, and zooming semantics. Our approach adds short animations during user interaction that help to explore the data efficiently and aid the user in the detection of unknown features.
Evaluation of Geometric Registration Methods for Using Spatial Augmented Reality in the Automotive Industry
(The Eurographics Association, 2010) Menk, Christoffer; Jundt, Eduard; Koch, Reinhard; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Spatial augmented reality is especially interesting for the automotive industry, because in the production process of a car a lot of virtual content and also real objects are used. Therefore, the virtual content can be directly projected onto the real object to combine the advantages of the real and virtual world. One important issue for the usage of spatial augmented reality in automotive processes and applications is that the virtual content has to be projected with a very high accuracy onto the real object, because decisions are made on the basis of the projection. Therefore, we present in this article a new method for the evaluation of geometric registration techniques which align a projector to a real object. Additionally, we use this proposed method to evaluate existing geometric registration techniques. Furthermore, we present a new application where a projector is used to support the design process of a new car.
Feature Preserving Sketching of Volume Data
(The Eurographics Association, 2010) Kerber, Jens; Bokeloh, Martin; Wand, Michael; Krüger, Jens; Seidel, Hans-Peter; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
In this paper, we present a novel method for extracting feature lines from volume data sets. This leads to a reduction of visual complexity and provides an abstraction of the original data to important structural features. We employ a new iteratively reweighted least-squares approach that allows us to detect sharp creases and to preserve important features such as corners or intersection of feature lines accurately. Traditional least-squares methods This is important for both visual quality as well as reliable further processing in feature detection algorithms. Our algorithm is efficient and easy to implement, and nevertheless effective and robust to noise. We show results for a number of different data sets.
Geometric Reconstruction of the Ostium of Cerebral Aneurysms
(The Eurographics Association, 2010) Neugebauer, Mathias; Diehl, Volker; Skalej, Martin; Preim, Bernhard; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Polygonal 3D-reconstructions of cerebral aneurysms, combined with simulated or measured flow data provide important information for medical research, risk assessment and therapy planning. Landmarks, orientation axis, and a subdivision into functional unities, support the purposeful exploration of this complex data. The ostium, the area of inflow into the aneurysm, is the reference structure for various landmarks, axis and the initial subdivision into aneurysm's body and parent vessel.We present an approach to automatically extract important landmarks and geometrically reconstruct the ostium. Our method was successfully applied to various types of saccular aneurysms. These results were discussed with radiology experts. Our approach was considered as useful to reduce interpersonal variance in the ostium determination and forms a basis for subsequent quantification and exploration.
Geometry-aware Video Registration
(The Eurographics Association, 2010) Palma, Gianpalo; Callieri, Marco; Dellepiane, Matteo; Corsini, Massimiliano; Scopigno, Roberto; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
We present a new method for the accurate registration of video sequences of a real object over its dense triangular mesh. The goal is to obtain an accurate video-to-geometry registration to allow the bidirectional data transfer between the 3D model and the video using the perspective projection defined by the camera model. Our solution uses two different approaches: feature-based registration by KLT video tracking, and statistic-based registration by maximizing the Mutual Information (MI) between the gradient of the frame and the gradient of the rendering of the 3D model with some illumination related properties, such as surface normals and ambient occlusion. While the first approach allows a fast registration of short sequences with simple camera movements, the MI is used to correct the drift problem that KLT tracker produces over long sequences, due to the incremental tracking and the camera motion. We demonstrate, using synthetic sequences, that the alignment error obtained with our method is smaller than the one introduced by KLT, and we show the results of some interesting and challenging real sequences of objects of different sizes, acquired under different conditions.
Gerbil - A Novel Software Framework for Visualization and Analysis in the Multispectral Domain
(The Eurographics Association, 2010) Jordan, Johannes; Angelopoulou, Elli; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Multispectral imaging has been gaining popularity and has been gradually applied to many fields besides remote sensing. Multispectral data provides unique information about material classification and reflectance analysis in general. However, due to the high dimensionality of the data, both human observers as well as computers, have difficulty interpreting this wealth of information. We present a new software package that facilitates the visualization of the relationship between spectral and topological information in a novel fashion. It puts emphasis on the spectral gradient, which is shown to provide enhanced information for many reflectance analysis tasks. It also includes a rich toolbox for evaluation of image segmentation and other algorithms in the multispectral domain. We combine the parallel coordinates visualization technique with hashing for a highly interactive visual connection between spectral distribution, spectral gradient and topology. The framework is released as open-source, has a modern cross-platform design and is well integrated into existing established computer vision software (OpenCV).
Global Illumination using Parallel Global Ray-Bundles
(The Eurographics Association, 2010) Hermes, Jan; Henrich, Niklas; Grosch, Thorsten; Mueller, Stefan; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
A fast computation of unbiased global illumination is still an unsolved problem, especially if multiple bounces of light and non-diffuse materials are included. The standard Monte Carlo methods are time-consuming, because many incoherent rays are shot into the scene, which is hard to parallelize. On the other hand, GPUs can make the most of their computing power if the problem can be broken down into many parallel, small tasks. Casting global, parallel ray-bundles into the scene is a way of achieving this parallelism. We exploit modern GPU features to extract all intersection points along each ray within a single rendering pass. Radiance can then be transferred between pairs of all points which allows an arbitrary number of interreflections, especially for compelling multiple glossy reflections. Beside arbitrary BRDFs, our method is independent of the number of light sources and can handle arbitrary shaped light sources in a unified framework for unbiased global illumination. Since many methods exist for fast computation of direct light using soft shadows, we demonstrate how our method can be built on top of any direct light simulation.
Graphical Interface Models for Procedural Mesh Growing
(The Eurographics Association, 2010) Menz, Stefan; Dammertz, Holger; Hanika, Johannes; Weber, Michael; Lensch, Hendrik P. A.; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
Procedural modeling allows to create highly complex 3D scenes from a small set of construction rules, which has several advantages over storing the full data of an object. The most important ones are a very small memory footprint and the ability to generate infinite variations of one prototype object by using the same set of rules. However, the problem that procedural modeling imposes on the user is to define a reasonable set of rules to generate a specific object. To simplify this task, we present new interaction metaphors for a graphical user interface and a minimal set of geometric operations that allow the user to efficiently create such rules and the respective models. These metaphors are then implemented in a prototype system and are evaluated by user tests with regard to usability and user performance. The results show that the system enables even inexperienced users to create complex 3D objects via procedural modeling using the presented approach.

Browse

Browsing VMV10 by Title

Results Per Page

Sort Options