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The broad range of methods for virtual humanoids and their evaluation as avatars in virtual environments is handled in this thesis. The enabling methods, as well as experimental evaluations are the main contributions of the thesis. The central conclusion of the work can be summed up as the fact that virtual humanoids are beneficial for a number of interaction scenarios typically found in virtual environments. The thesis presents the technology required for an interactive simulation of virtual humanoids in virtual environments. It presents the VRZula toolkit and its main features, mainly a layered data structure derived from functional anatomy, separation of data and simulation algorithms, and the control and propagation of modifications to the data. This elementary approach leads to an extendible and flexible system for virtual humanoids. The toolkit is capable of simulating even sophisticated models of virtual humanoids in complex distributed virtual environments. It integrates a variety of current approaches to the representation of virtual humanoids, as well as methods for kinematic and physiology simulation. Substantial improvements and novel approaches are introduced in the areas of deformation of musculature, multimodal representation and synchronization, construction of motion graphs, and synchronous body tracking. Within the scope of this work, the VRZula toolkit is used for the evaluation of several hypotheses regarding the application of virtual humanoids in virtual environments. The two studies presented contribute to the understanding of the influence of virtual humanoids on the sensation of presence. It has been shown that avatars equipped with synchronous kinematics affect the real motion of the user and optimize the kinematics in the virtual world. Even though the mental and attentional resources bound to the exocentric virtual body representation led to a decrease of presence scores in room-mounted virtual environments, a strong identification of the user with the avatar has been shown. In addition, correlations between presence scores and physiological, as well as performance measures have been found. The results of the two studies are the basis of the evaluation of virtual humanoids used as avatars in typical interaction scenarios of virtual environments, and identify beneficial areas of application in certain navigation tasks and most manipulation scenarios. The use of avatars equipped with synchronous kinematics is clearly recommended. The VRZula toolkit developed within this work and the experimental evaluations have contributed to the prevailing knowledge on virtual humanoids and their application in virtual environments. The thesis demonstrates that virtual humanoids are the central methodology in future interaction techniques of sophisticated virtual environments. |
