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Image-based Capture and Modeling of Dynamic Human Motion and Appearance
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- Author / Creator
- Birkbeck, Neil Aylon Charles
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Photo-realistic renderings of humans are required for real-time graphics applications, and accurate
human models are useful in applications such as model-based tracking. Non-rigid deformations
of humans, e.g., deforming cloth and muscle bulging, are hard to model geometrically and are
inefficient to simulate. Such deformations are often dependent on the subjects kinematic pose. In this
thesis, an image-based pipeline is used to acquire a compact model of these non-rigid deformations.
The model is capable of generating photo-realistic renderings of deformation and appearance effects
from novel animation and viewpoint.The compact model of non-rigid deformations is distilled from a multi-view training sequence
exhibiting the desired pose-dependent deformations. The geometric deformations are modeled with
a pose-dependent geometry attached to a kinematic skeleton, and the appearance is modeled with
a pose- and view-dependent appearance basis. Pose-dependent effects not encoded in the geometry
are represented in the appearance, and view-dependent appearance compensates for inaccurate
geometries and specular effects.In acquisition, a base geometry is recovered from a static multi-view image sequence. For human
geometries, a two camera turntable-based acquisition is proposed. The acquisition interleaves
tracking and silhouette refinement to account for unintentional motion of the subject.The coarse motion of the base geometry is tracked in a separate training sequence using a common
tracking formulation for linear blend skinned meshes. The energy formulation combines silhouette
or intensity-based data terms with pose prior and smoothness terms. Local optimization with
GPU acceleration gives near-real time results on intensity-based terms.The recovery of fine-scale geometric deformations necessary to build the model is studied in
situations with a few or non-overlapping views. For a moving monocular camera, a simple constant
velocity constraint is shown to enable the reconstruction of both dense scene flow and structure in
a variational formulation. This simple constraint is generalized to a multi-view setting, where long
range flow is represented with a temporal motion basis layered on top of a geometric proxy surface.The complete compact model is demonstrated on several examples, including modeling of cloth
deformation on arms, transferring the appearance of wrinkles on pants to novel walk cycles, and
applications of free-viewpoint compression. -
- Graduation date
- Fall 2011
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.