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2D & 3D Reconstruction

Free-form reconstruction through the use of
implicit polynomial (IP) curve & surface models

Implicit Polynomials (IP) are a powerful and rich mean to represent smooth approximations of 2D curves and 3D surfaces,

A d^th degree IP surface if the zero set of a d^th degree explicit polynomial. That is, the set of points (x,y,z) where the explicit polynomial is s.t. :

f(x,y,z) = SUM (i+j+k <= d)    { c_ijk * x^i * y^j * z^k }= 0

Such surfaces are generalizations of quadrics, e.g. hyper-ellipsoids, to more complicated shapes.

Initial shape. Fit without CP. Fit with 3 CPs.
Zoom: no CP. Zoom: with CPs. Final fit with CPs.
Example of an 8^th degree 3L fit of a butterfly shape with or without Control Points (CP).

The 3L fitting algorithm has been recently developed at LEMS. It is a robust and repeatable, under Euclidean transformations, process implemented as Linear LSE polynomial fitting.

Initial head data set 10^th degree fit (ears discarded) Reconstruction from 12 patches using 4^th degree IP surface models.
Fitting the head data set using 3L algorithm


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