This thesis addresses the question to what extent it is possible to reconstruct human full-body motions from very sparse control signals. To this end, we first investigate the use of multi-linear representations of human motions. We show that multi-linear motion models together with knowledge from prerecorded motion capture databases can be used to realize a basic motion reconstruction framework that relies on very sparse inertial sensor input only. However, due to the need for a semantic pre-classification of the motion to be reconstructed and rather restricting database requirements, the described framework is not suitable for a more general motion capture scenario. We address these issues in a second, more flexible approach, which relies on sparse accelerometer readings only. Specifically, we employ four 3D accelerometers that are attached to the extremities of a human actor to learn a series of local models of human poses at runtime. The main challenge in generating these local models is to find a reliable mapping from the lowdimensional space of accelerations to the high-dimensional space of human poses or motions. We describe a novel online framework that successfully deals with this challenge. In particular, we introduce a novel method for very efficiently retrieving poses and motion segments from a large motion capture database based on a continuous stream of accelerometer readings, as well as a novel prior model that minimizes reconstruction ambiguities while simultaneously accounting for temporal and spatial variations. Thirdly, we will outline a conceptually very simple yet very effective framework for reconstructing motions based on sparse sets of marker positions. Here, the sparsity of the control signal results from problems that occurred during a motion capture session and is thus unintentional. As a consequence, we do not control the information we can access, which introduces several new challenges. The basic idea of the presented framework is to approximate the original performance by rearranging suitable, time-warped motion subsequences retrieved from a knowledge base containing motion capture data that is known to be similar to the original performance.
Reconstruction of Human Motions Based on Low-Dimensional Control Signals
2012-08-09
Hochschulschrift
Elektronische Ressource
Englisch
Computeranimation , Bewegungserfassung , Bewegungsrekonstruktion , Bewegungssynthese , Beschleunigungssensoren , Inertialsensoren , Multilineares Modell , Tensoren , computer animation , motion capture , motion synthesis , motion reconstruction , motion retrieval , accelerometers , inertial sensors , multi-linear model , tensors , online lazy neighborhood graph , subsequence graph , dynamic time warping , ddc:004
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