Abstract:
The human skin is the largest organ of the human body. It is a complex structure with anisotropic, heterogenous and viscoelastic properties lending itself to numerous aspects of the human body. It is because of this that there has been a major focus to characterise the behaviour of skin. Available instrumentation are able to apply a rich a set of deformations to regions of skin allowing for the anisotropic and non-homogenous properties to be studied. However to acquire a full understanding of how the skin is deforming, surface strains need to be analysed. This can be done by using a non-contact stereosustem. Surface deformation and therefore can be measure using stereoscopy. This investigation looked to implement a novel phase-based cross-correlation method developed at the Auckland Bioengineering Institute. It was implemented for a 3-camera stereoscopic system to track material points individually through 3D space. The phase-based cross-correlation was method characterised for a series of in-plane and out-of-plane tracking and compared against a normal cross-correlation based method. A series of unconstrained and constrained matching, with sampling from neighbouring material points, was used. In addition to this, a deformation function was incorporated into the matching algorithm to compensate for perspective distortions and shearing. Linear displacements were tracked to subpixel accuracy and measurements of in-plane angular rotation location estimates were accurate to under a micron.
