Browsing by Author "Wacker, Markus"

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    Estimation of Muscle Activity in One-Leg Stance from 3D Surface Deformation
    (The Eurographics Association, 2018) Metzler, Johannes; Neumann, Thomas; Gassel, Stefanie; Friedrich, Jens; Wacker, Markus; Puig Puig, Anna and Schultz, Thomas and Vilanova, Anna and Hotz, Ingrid and Kozlikova, Barbora and Vázquez, Pere-Pau
    Muscular activity during human motion is usually quantified by measuring the electrical potential during muscle activation using electromyography (EMG). However, apart from producing electrical activity, muscular contraction of many skeletal muscles also induces subtle deformation of the skin surface. In this paper, we present a method to estimate muscular activation from such 3D skin deformation. To this end, we introduce a capture system that reconstructs the 3D motion of the skin from multi-view video data and simultaneously measures true muscle activity with EMG sensors. Our data reveals strong correlations between the skin deformation and muscular activity during one-leg stances. We propose a pose normalization procedure and a novel model based on Supervised Principal Component Regression that automatically segments individual muscles and estimates their activation from 3D surface deformation. Our evaluation shows that the model generalizes to varying body shapes and that the estimated activation closely fits the measured EMG data.
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    Visualization of Orientations of Spatial Historical Photographs
    (The Eurographics Association, 2018) Bruschke, Jonas; Niebling, Florian; Wacker, Markus; Sablatnig, Robert and Wimmer, Michael
    Historical imagery are an important basis for research in Digital Humanities (DH). Especially art and architectural historians rely on historical photographs that are provided by online media repositories. In general, querying those image repositories is based on metadata. Unfortunately, these are often incomplete, imprecise, or wrong, impeding the search process. Using photogrammetric methods to spatialize the historical imagery, keyword-based search is enhanced by time- and location-dependent browsing methods within a four-dimensional model. The interactive, spatial presentation and exploration of these images opens up new potentials to answer research questions related to art and architectural historical science. One important aspect of the work presented here is to provide visualization methods that present statistical information about image positions, and in particular camera orientations. In addition to heat maps, we present adaptations of methods from flow field visualization to enable the exploration of camera orientations in large numbers of photographic images.