Infoscience

Report

# Laplacian Operator, Diffusion Flow and Active Contour on non-Euclidean Images

We propose here some basic approaches to direct processing of the $360^o$-images as we take into consideration the geometry of each one. Obviously, the geometry of each of these images is a consequence of the geometry of the sensor's mirror used. This technical report is organized as follows: In the first section we develop the Laplacian operator on non-Euclidean manifolds. First we start by derivation of Laplacian operator on Riemannian manifolds and than we derive it explicitly for each of the non-Euclidean manifolds of our interest, i.e. hyperboloid, sphere and paraboloid. This allows us to implement the gradient and diffusion flow on hyperbolic and spherical image. For testing this techniques, a synthetic and a real image was used in the case of hyperboloid and sphere respectively. Then we demonstrate the active contour on non-Euclidean images. First it was derived by directly minimizing the energy functional where the specific geometry of the non-Euclidean image was taken into account. Then the same was proofed through Polyakov action. We give some examples in each of the cases and so derive conclusions about the influence of the geometry for each particular case.

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ITS

#### Reference

• EPFL-REPORT-87176

Record created on 2006-06-14, modified on 2017-05-10