Johnny T. Chang

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Hair exhibits strong anisotropic dynamic properties which demand distinct dynamic models for single strands and hair-hair interactions. While a single strand can be modeled as a multibody open chain expressed in generalized coordinates, modeling hair-hair interactions is a more difficult problem. A dynamic model for this purpose is proposed based on a(More)
BACKGROUND Although symmetry is hailed as a fundamental goal of aesthetic and reconstructive surgery, our tools for measuring this outcome have been limited and subjective. With the advent of three-dimensional photogrammetry, surface geometry can be captured, manipulated, and measured quantitatively. Until now, few normative data existed with regard to(More)
We present methods for recovering surface height fields such as geometric details of 3D textures by incorporating shadow constraints. We introduce shadow graphs which give a new graph-based representation for shadow constraints. It can be shown that the shadow graph alone is sufficient to solve the shape-from-shadow problem from a dense set of images.(More)
We present a method to solve shape-from-shadow using shadow graphs which give a new graph-based representation for shadow constraints. It can be shown that the shadow graph alone is enough to solve the shape-from-shadow problem from a dense set of images. Shadow graphs provide a simpler and more systematic approach to represent and integrate shadow(More)
PURPOSE The pedicled reverse-flow lateral arm flap has been described primarily for the reconstruction of nontraumatic elbow wounds. We describe our experience using this flap in staged operations for soft tissue coverage after elbow trauma, including acute coverage of open fractures and salvage of infected hardware. METHODS Review of patients who(More)
This paper presents a novel approach for estimating the flow fields of dynamic temporal textures whose motion differs radically from that of rigid bodies. Our approach is based on a local flow probability distribution function at each pixel using the STAR model and the data from a spatio-temporal neighborhood. The peak of this density function can be(More)
BACKGROUND In cases of mutilating hand injuries, the primary goal is recovery of prehensile function. This is particularly true in the case of joints, which are extremely difficult to replace or reconstruct adequately when damaged. Heterotopic vascularized joint transfer is indicated when salvageable joints are available for transfer to a more functionally(More)
BACKGROUND Orbital reconstruction requires knowledge of orbital depth in order to prevent optic nerve injury. Numerous analyses of adult orbital dimensions have been undertaken previously in order to characterize this measurement, including skull specimen and computerized tomography studies. However, there is a paucity of information regarding the pediatric(More)