Publications

Intersection of conic sections using geometric algebra

authors Clément Chomicki, Stéphane Breuils, Venceslas Biri, Vincent Nozick.
title Intersection of conic sections using geometric algebra.
conference CGI ENGAGE 2023, Aug 2023, Shanghai, China. pp.175-187
DOI https://dx.doi.org/10.1007/978-3-031-50078-7_14
HAL ID ⟨hal-04210085⟩

Comments

One of the goals of my thesis was to find a nice method to extract points from conics intersections objects, in a 2D version of QCGA that we called QC2GA. It is when working on that specific problem that I realized that considering these objects as pencils of conics helped to understand and manipulate them. This paper received the best presentation award of ENGAGE, and an extension has been published in the journal AACA.

Conics, Their Pencils and Intersections in Geometric Algebra

authors Clément Chomicki, Stéphane Breuils, Venceslas Biri, Vincent Nozick.
title Conics, Their Pencils and Intersections in Geometric Algebra
journal Advances in Applied Clifford Algebras 35, 1 (2025)
DOI https://doi.org/10.1007/s00006-024-01356-5
HAL ID ⟨hal-04774264⟩
   

Pencils of CGA for Voronoi and Power Diagrams

authors Clément Chomicki, Stéphane Breuils, Venceslas Biri, Vincent Nozick.
title Pencils of CGA for Voronoi and Power Diagrams.
conference CGI ENGAGE 2024, Jul 2024, Geneva, Switzerland.
DOI incomming
HAL ID ⟨hal-04636752⟩

Comments

We realized that pencils of circles are very convenient to compute the interface of two Voronoi Diagram cells. This also generalizes to any Power diagram with or without multiplicative weight.* Pencils and set operators in 3D CGA The paper have been accepted and presented at the conference, but we are waiting for it to be published.

Pencils and set operators in 3D CGA

authors Clément Chomicki, Stéphane Breuils, Venceslas Biri, Vincent Nozick.
title PENCILS AND SET OPERATORS IN 3D CGA.
conference AGACSE 2024, Aug 2024, Amsterdam, Netherlands.
DOI incomming
HAL ID ⟨hal-04569529⟩

We applied the pencils frameworks to circles of 3D CGA, who are \(2\)-pencils of spheres. All these results probably generalize to pencils of higher order, but this has not been tested yet.

The paper have been accepted and presented at the conference, but we are waiting for it to be published.

My Thesis

title Geometric Algebras for Conics Intersections and Generalization to Pencils of Algebraic Hypersurfaces
HAL ID ⟨https://theses.hal.science/tel-04998794⟩
date 28/11/2024
video https://www.youtube.com/watch?v=6bNnGOwPwsY

Jury

Membre Affiliation Rôle
Prof. Laurent Fuchs XLIM Rapporteur
Prof. Nicolas Magaud ICube Rapporteur
Prof. Raphaëlle Chaine LIRIS Examinatrice
Dr. Pooran Memari Polytechnique Examinatrice
Dr. Stéphane Breuils LAMA Examinateur
Dr. Vincent NOZICK LIGM Directeur
Prof. Venceslas BIRI LIGM Co-encadrant

Summary

Geometric algebra is an elegant tool for dealing with geometric problems and takes a place of increasing importance in many domains. Among many algebras, GAC (Geometric Algebra for Conics) and QC2GA (Quadric Conformal Two-Dimensional Algebra) allow to represent conics and their intersections. This thesis is then about trying to extract the points of conic-conic intersection objects of QC2GA.This task is achieved successfully in this thesis, and is the precursor for the making of framework based on pencils of shapes for the conception and consideration of geometric algebra based on blades of points. The resulting framework is then applied first to 3D CGA (conformal geometric algebra) for developing some set operators for pencils of spheres and applying them for finding the smallest tangent sphere of two skew lines, and lastly to 2D CGA for constructing Voronoi and power diagram as well as their multiplicatively weighted version with pencils of circles

Created: 2025-12-06 Sat 12:57