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Bijectivity of digitized linear transformations is crucial when transforming 2D/3D objects in computer graphics and computer vision. Although characterisation of bijective digitized rotations in 2D is well known, the extension to 3D is still an open problem. A certification algorithm exists that allows to verify that a digitized 3D rotation defined by a quaternion is bijective. In this paper, we use geometric algebra to represent a bijective digitized rotation as a pair of bijective digitized reflections. Visualization of bijective digitized reflections in 3D using geometric algebra leads to a conjectured characterization of 3D bijective digitized reflections and, thus, rotations. So far, any known quaternion that defines a bijective digitized rotation verifies the conjecture. An approximation method of any digitized reflection by a conjectured bijective one is also proposed.

In this demonstration, we are going to propose an interactive animation of analytically defined discrete conics (quadrics in 2D) and discrete quadrics in 3D. The digitization is performed on the 2D quadratic equation: Ax2 + Bxy + Cy2 + Dx + Ey + F = 0 and the 3D quadric equation Ax2 + By2 + Cz2 + Dxy + Exz + F yz + Gx + Hy + Iz + J = 0.We propose 4 and 8-connected discrete 2D conics (naive and standard discrete conics) defined analytically where the user can see the resulting discrete conic while interacting with the parameters A, B, C, D, E and F. In the same way, we propose 6-separating and tunnel free 3D quadrics (naive and standard 3D quadrics) defined analytically where the user can can interactively modify the parameters A, B, C, D, E, F, G, H, I and J.

Within the framework of the development of a software which aims at unifying geometrical modelisation and image processing, based on both analytical and voxels representation of objects, we wish to extend this to parametrical objects. We focus, in this paper, on the study of parametrical simplexes and their relation with the discrete supercover model. Besides, we obtain a simple and incremental algorithm to run over nD discrete objects. This is also the basis of parametrical curves and surfaces studies.