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Author: Botsch, Mario × Start date: 2011 × End date: 2018 ×

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Now showing 1 - 10 of 12
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    Online Adaptive PCA for Inverse Kinematics Hand Tracking
    (The Eurographics Association, 2014) Schröder, Matthias; Botsch, Mario; Jan Bender and Arjan Kuijper and Tatiana von Landesberger and Holger Theisel and Philipp Urban
    Recent approaches to real-time bare hand tracking estimate the hand's pose and posture by fitting a virtual hand model to RGBD sensor data using inverse kinematics. It has been shown that exploiting natural hand synergies can improve the efficiency and quality of the tracking, by performing the optimization in a reduced parameter space consisting of realistic hand postures [SMRB14]. The downside, however, is that only postures within this subspace can be tracked reliably, thereby trading off flexibility and accuracy for performance and robustness. In this paper we extend the previous method by introducing an adaptive synergistic model that is automatically adjusted to observed hand articulations that are not covered by the initial subspace. Our adaptive model combines the robustness of tracking in a reduced parameter space with the flexibility of optimizing for the full articulation of the hand, which we demonstrate in several synthetic and real-world experiments.
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    Evaluation of Surround-View and Self-Rotation in the OCTAVIS VR-System
    (The Eurographics Association, 2013) Dyck, Eugen; Pfeiffer, Thies; Botsch, Mario; Betty Mohler and Bruno Raffin and Hideo Saito and Oliver Staadt
    In this paper we evaluate spatial presence and orientation in the OCTAVIS system, a novel virtual reality platform aimed at training and rehabilitation of visual-spatial cognitive abilities. It consists of eight touch-screen displays surrounding the user, thereby providing a 360! horizontal panorama view. A rotating office chair and a joystick in the armrest serve as input devices to easily navigate through the virtual environment. We conducted a two-step experiment to investigate spatial orientation capabilities with our device. First, we examined whether the extension of the horizontal field of view from 135! (three displays) to 360! (eight displays) has an effect on spatial presence and on the accuracy in a pointing task. Second, driving the full eight screens, we explored the effect of embodied self-rotation using the same measures. In particular we compare navigation by rotating the world while the user is sitting stable to a stable world and a self-rotating user.
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    Pose Correction by Space-Time Integration
    (The Eurographics Association, 2011) Esturo, Janick Martinez; Rössl, Christian; Fröhlich, Stefan; Botsch, Mario; Theisel, Holger; Peter Eisert and Joachim Hornegger and Konrad Polthier
    The deformation of a given model into different poses is an important problem in computer graphics and computer animation. In a typical workflow, a carefully designed reference surface is deformed into a couple of poses, which can then act as a basis for interpolating arbitrarily intermediate poses. To this end the input poses should be free of geometric artifacts like self-intersections, since these degeneracies will be reproduced or even amplified by the interpolation. Not only are the resulting artifacts visually disturbing, they typically cause severe numerical problems for further downstream applications. In this paper we present an automatic approach for removing these geometric artifacts from a given set of mesh poses, while maintaining the original mesh connectivity. The deformation from the rest pose to a target pose is faithfully reproduced by integration of a smooth space-time vector field, which by construction guarantees the absence of self-intersections in the repaired target pose. Our approach is computationally efficient, and its effectiveness is demonstrated on a range of typical animation examples.
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    OctaVis: A Virtual Reality System for Clinical Studies and Rehabilitation
    (The Eurographics Association, 2013) Zell, Eduard; Dyck, Eugen; Kohsik, Agnes; Grewe, Philip; Flentge, David; Winter, York; Piefke, Martina; Botsch, Mario; Hans-Christian Hege and Anna Vilanova
    Brain function disorders, resulting for instance from stroke, epilepsy, or other incidents can be partially recovered by rehabilitation training. Performing neuro-rehabilitation in virtual reality systems allows for training scenarios close to daily tasks, is easily adaptable to the patients' needs, is fully controllable by clinical staff, and guarantees patient safety at all times. In this paper, we describe the OCTAVIS system, a novel virtual reality platform developed primary for clinical studies with and rehabilitation training of patients with brain function disorders. To meet the special requirements for clinical use, our system has been designed with ease of use, ease of maintenance, patient safety, space and cost efficiency in mind. Our system has been successfully deployed to four hospitals, where it is used for rehabilitation training and clinical studies. We report first results of these studies, demonstrating that our system is immersive, easy to use, and supportive for rehabilitation purposes.
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    ELASTIFACE: Matching and Blending Textured Faces
    (ACM, 2013) Zell, Eduard; Botsch, Mario; Forrester Cole and Cindy Grimm
    In this paper we present ELASTIFACE, a simple and versatile method for establishing correspondence between textured face models, either for the construction of a blend-shape facial rig or for the exploration of new characters by morphing between a set of input models. While there exists a wide variety of approaches for inter-surface mapping and mesh morphing, most techniques are not suitable for our application: They either require the insertion of additional vertices, are limited to topological planes or spheres, are restricted to near-isometric input meshes, and/or are algorithmically and computationally involved. In contrast, our method extends linear non-rigid registration techniques to allow for strongly varying input geometries. It is geometrically intuitive, simple to implement, computationally efficient, and robustly handles highly non-isometric input models. In order to match the requirements of other applications, such as recent perception studies, we further extend our geometric matching to the matching of input textures and morphing of geometries and rendering styles.
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    Robust Articulated-ICP for Real-Time Hand Tracking
    (The Eurographics Association and John Wiley & Sons Ltd., 2015) Tagliasacchi, Andrea; Schröder, Matthias; Tkach, Anastasia; Bouaziz, Sofien; Botsch, Mario; Pauly, Mark; Mirela Ben-Chen and Ligang Liu
    We present a robust method for capturing articulated hand motions in realtime using a single depth camera. Our system is based on a realtime registration process that accurately reconstructs hand poses by fitting a 3D articulated hand model to depth images. We register the hand model using depth, silhouette, and temporal information. To effectively map low-quality depth maps to realistic hand poses, we regularize the registration with kinematic and temporal priors, as well as a data-driven prior built from a database of realistic hand poses. We present a principled way of integrating such priors into our registration optimization to enable robust tracking without severely restricting the freedom of motion. A core technical contribution is a new method for computing tracking correspondences that directly models occlusions typical of single-camera setups. To ensure reproducibility of our results and facilitate future research, we fully disclose the source code of our implementation.
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    Accurate Face Reconstruction through Anisotropic Fitting and Eye Correction
    (The Eurographics Association, 2015) Achenbach, Jascha; Zell, Eduard; Botsch, Mario; David Bommes and Tobias Ritschel and Thomas Schultz
    Fitting a facial template model to 3D-scanner data is a powerful technique for generating face avatars, in particular in the presence of noisy and incomplete measurements. Consequently, there are many approaches for the underlying non-rigid registration task, and these are typically composed from very similar algorithmic building blocks. By providing a thorough analysis of the different design choices, we derive a face matching technique tailored to high quality reconstructions from high resolution scanner data. We then extend this approach in two ways: An anisotropic bending model allows us to more accurately reconstruct facial details. A simultaneous constrained fitting of eyes and eye lids improves the reconstruction of the eye region considerably.
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    Example‐Driven Deformations Based on Discrete Shells
    (The Eurographics Association and Blackwell Publishing Ltd., 2011) Fröhlich, Stefan; Botsch, Mario; Eduard Groeller and Holly Rushmeier
    Despite the huge progress made in interactive physics‐based mesh deformation, manipulating a geometrically complex mesh or posing a detailed character is still a tedious and time‐consuming task. Example‐driven methods significantly simplify the modelling process by incorporating structural or anatomical knowledge learned from example poses. However, these approaches yield counter‐intuitive, non‐physical results as soon as the shape space spanned by the example poses is left. In this paper, we propose a modelling framework that is both example‐driven and physics‐based and thereby overcomes the limitations of both approaches. Based on an extension of the discrete shell energy we derive mesh deformation and mesh interpolation techniques that can be seamlessly combined into a simple and flexible mesh‐based inverse kinematics system.
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    Adaptive Remeshing for Real-Time Mesh Deformation
    (The Eurographics Association, 2013) Dunyach, Marion; Vanderhaeghe, David; Barthe, Loïc; Botsch, Mario; M.- A. Otaduy and O. Sorkine
    We present an adaptive isotropic remeshing technique that is fast enough to be used in interactive applications, such as mesh deformation or mesh sculpting. Previous real-time remeshing techniques are either not adaptive, hence requiring too many triangles, or make compromises in terms of triangle quality. High quality adaptive remeshing techniques are too slow for interactive applications. In this short paper we present a simple extension of a uniform remeshing approach that results in an efficient, yet high quality, curvature-adaptive remeshing.
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    A Multilinear Model for Bidirectional Craniofacial Reconstruction
    (The Eurographics Association, 2018) Achenbach, Jascha; Brylka, Robert; Gietzen, Thomas; Hebel, Katja zum; Schömer, Elmar; Schulze, Ralf; Botsch, Mario; Schwanecke, Ulrich; Puig Puig, Anna and Schultz, Thomas and Vilanova, Anna and Hotz, Ingrid and Kozlikova, Barbora and Vázquez, Pere-Pau
    We present a bidirectional facial reconstruction method for estimating the skull given a scan of the skin surface and vice versa estimating the skin surface given the skull. Our approach is based on a multilinear model that describes the correlation between the skull and the facial soft tissue thickness (FSTT) on the one hand and the head/face surface geometry on the other hand. Training this model requires to densely sample the Cartesian product space of skull shape times FSTT variation, which cannot be obtained by measurements alone. We generate this data by enriching measured data-volumetric computed tomography scans and 3D surface scans of the head-by simulating statistically plausible FSTT variations. We demonstrate the versatility of our novel multilinear model by estimating faces from given skulls as well as skulls from given faces within just a couple of seconds. To foster further research in this direction, we will make our multilinear model publicly available.