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Author: search.filters.author.Tosranon, PrasongSubject: search.filters.subject.Surface

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    3D face alignment and registration in the presence of facial expression diff{ligature}erences
    (2013-01-01)
    Pintavirooj, Chuchart
    ;
    Cohen, Fernand S.
    ;
    Tosranon, Prasong
    This paper deals with the problem of 3D alignment of faces in the presence of some facial expression changes. The data are three dimensional and obtained using a laser scanner. Our approach is based on the diff{ligature}erential geometry of the surface and computes the intrinsic local fi{ligature}ducial points on the surface and on curves that reside on the surface. Because these fi{ligature}ducial points are local, they allow partial alignment, where part of the face is viewed. Moreover, since the fi{ligature}ducial points are relatively affi{ligature}ne-invariant to local affi{ligature}ne transformations, they allow matching and alignment when facial expression changes aff{ligature}ect part of the face. A fast, noniterative alignment procedure is presented in this paper that establishes reliable correspondences between fi{ligature}ducial points without any prior knowledge of the overall nonlinear global transformation that takes place after the changes in facial expressions. This is achieved through the construction of a set of ordered novel absolute local affi{ligature}ne invariants. With enough fi{ligature}ducial points set as correspondents, the overall nonlinear transformation is computed and the face before and after the transformation are aligned. For comparison, we also compare the alignment performance of our method with that of the iterative closest point (ICP) method and the coherent point drift (CPD) method which is based on the Gaussian mixture model by looking at the between-to-within variation (signal-to-noise ratio, SNR) between these two classes (match vs nonmatch) based on the average alignment errors for the genuine matches and nonmatches, normalized by their respective within variation, and by running it on the 3D face database GavabDB. The separation between the true match and nonmatch is best for our zero-torsion method (SNR of 1.2), followed by the ICP method (SNR of 0.37)and the CPD method (SNR of 0.15). It is interesting to observe here that, although the alignment error for the true match cases is lowest for the CPD method, it is also extremely low for the nonmatch cases, which would mean that the method would force a query into a wrong face, yielding poor specificity (lots of false alarms). © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
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    Using intrinsic surface geometry and absolute invariants for 3D face alignment and registration
    (2010-12-01)
    Pintavirooj, Chuchart
    ;
    Tosranon, Prasong
    ;
    Cohen, Fernand S.
    In this paper we derive novel surface fiducial points that are computed from the differential geometry of the surface. The fiducial intrinsic points are intrinsic, local, and relative invariants, i.e., they are preserved under similarity, affine, and nonlinear transformations that are piecewise affine. As the fiducial points are computed from high order surface shape derivatives, their sensitivity to any noise either due to measurement error or local distortion is high. To reduce these effects, we use a B-Spline curve/surface representation that smoothes out the curve/surface prior to the computation of these intrinsic invariant points. The fiducial points are used in a non-iterative geometric-based method for 3D shape matching and registration of human faces. The matching is achieved by establishing correspondences between fiducial points after a sorting based on a set of absolute local affine invariants derived from them. The performance of the matching based on these fiducial points although shown for face alignment, the overall approach is generic to the alignment a variety of objects for which these intrinsic fiducial points exist and for scenarios where the classes of nonlinear transformations are piecewise affine. © 2010 IEEE.