Team IGG : Computer Graphics and Geometry


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Main software developed by the team and valued

  • CGoGN is the geometric modeling platform of the IGG group. It is developped in C++ and provides an efficient and easy to use implementation of combinatorial maps, a topological model that allows the representation of meshes in any dimension (curves, surfaces, volumes, ...) and gives an optimal access to the neighborhood relations between the cells (vertices, edges, faces, ...). Several operators allow the manipulation of the meshes connectivity and many algorithms allow the computation of properties attached to the cells thanks to a dynamic attribute system. Multiresolution extensions allow the representation and traversal of objects at different scales. CGoGN enables the testing and integration of numerous works, in particular those concerning our works on geometric modeling and geometry processing (acquisition, deformation, subdivision, simplification, ...). Meshes representation also plays a fundamental role in many other fields such as numerical simulation in solid and fluid mechanics. Thanks to its genericity and efficiency, CGoGN is a particularly well suited library for this demanding context and several collaborations are currently underway.
  • We develop the ExRealis digitization platform. ExRealis offers a range of devices and software tools covering the whole digitization processing pipeline, from data acquisition to the creation of textured 3D models, that also proposes some tools for texture reconstruction and visualization accounting for complex lighting environments or material characteristics. Our software tools are based on out-of-core data structures and mechanisms that allow very large data management: millions of sample points and hundreds of photographs for a single object. ExRealis also includes a motion capture system for the animation of avatars in virtual reality or biomechanical applications. Our platform covers our needs in terms of acquisition and data processing and also makes it possible to capitalize developments achieved through our scientific production.
  • The GeoCoq library is the result of a Coq development started in 2006 with the thesis of Julien Narboux. It proposes the Coq formalisation of Tarski's geometry as described in the book "Metamathematische Methoden in der Geometrie" by W. Schwabhäuser et al. a large number of synthetic geometry theorems, tactics to simplify proofs, a study of the dependence links between various versions of the axiom of parallels, a fine study of decidability with different versions of the theory. Finally, through the coordination of geometry, it makes the link with the algebraic methods used in automatic proofs since the 1980s. This library contains about a hundred thousand lines of code and is freely available for researchers wanting to do proofs in geometry and/or certify geometric algorithms. The library has been partially ported to Isabelle. The part of GeoCoq concerning the formalisation of Euclid's elements has been integrated into Logipedia.

Other software deposited at the APP or on HAL

  • LARUS software developped by NARBOUX Julien and JANICIC Predrag, University of Belgrade, is an automatic theorem prover for coherent logic based on SAT/SMT solving.
  • PILOT software, developed by Caroline Essert and students, is protected by copyright. It was deposited at the Programs Protection Agency (APP) in Jul. 2015 under file n. IDDN.FR.001.280006.000.R.P.2015.000.31230: PILOT, and its spin-offs Brain-PILOT, RF-PILOT, Cryo-PILOT, is a preoperative assistance tool aiming at helping the surgeon in the decision-making process. It proposes automatically optimal trajectories for surgical tools (needles, electrodes) for percutaneous or keyhole procedures. It is currently under clinical testing in 3 different hospitals : Rennes Pontchaillou University Hospital, Pitié-Salpêtrière Paris Hospital, Strasbourg University Hospital, and expected soon at Trondheim hospital (Norway) and Brigham & Women's Hospital in Boston (USA).


  • Provisional patent application filed in the United States Patent Office on September 11, 2014. Serial No. 62/048,908. Inventors: Olga Dergachyova (30%), Caroline Essert (30%), Claire Haegelen (20%), Pierre Jannin (20%).


By way of its work on digitization, IGG team had the opportunity to execute several services (see also ExRealis framework):

  • Within the framework of the Eveil3D project, and in partnership with the technology transfer center Holo3, the digitization of two statues of the cathedral of Strasbourg has been performed in october 2013 for the Œuvre Notre Dame foundation. The goal was to use these statues in an immersive 3D environment for a language learning serious game.
  • The Inter-university House of Human Sciences (MISHA), Strasbourg, has at its disposal a huge collection of ethnographic artefacts, and has launched some years ago a project based on the OpenSIM game engine that provides a virtual world to make it possible the study and the contextualization of these artefacts. Obviously, this requires to have digital copies of them. A digitization campaign has thus been performed in autumn 2013 in order to produce digital copies of about ten african ethnographic artefacts.