Specifications, Constraints and Proofs in Geometry

Formalization and theorem proving in geometry

Illustration of Desargues theorem

Specification of a segmentation operation on 2D image represented by colored hypermaps (Détail)

Specification and resolution of geometric constraints

Geometric translation of a solution found algebraicaly

Direct construction

Formalization and planning of surgical interventions (Détail)

Inclusion of biomechanical simulations in the optimization loop [2-HPCE16].

Constraint solving for deep brain stimulation electrode placement [2-EHLA12].

Thermal propagation computation for cryoablation [2-JE15].

Possible insertion points on a Pareto front [4-HVCJ16].

Geometric Modeling, Simulation and Interaction

Adaptative and multiresolution volumic model

Volume subdivision of a torus with genus 3, modeled as a set of general polyhedra.

Automatic cell labeling to implicitly define a mesh hierarchy.

Detecting collisions in dynamic environments

Crowd simulation - Agents moving through mobile objects (red)

Crowd simulation - geographic data imported from OpenStreetMap

Crowd simulation - Building made of multiple levels

Crowd simulation - Virtual planet

Crowd simulation - Extreme topologies supported!

Virtual reality devices

Spidar & workbench

Gloves & wand

INCA

Haptic device's effector

Camera for position tracking

Real time simulation of cuts and tearing

An augmented elastic object undergoing large deformations and topological changes.

Augmented surgery sequence in medical environment.

Separation of degrees of freedom for manipulating objects

Study on the impact of degrees of freedom splitting for interaction in immersive environment.

Distances perception factor in virtual environments

Principle of hybrid projection and the various parameters used for the scene rendering.

The left picture shows the scene rendered with the standard perspective projection. The right picture shows an example from the same viewpoint with the hybrid projection. On the left picture, the user cannot see the chair legs in front of him.

Example of virtual visits: different location during the visit of a furnished house. Navigation path is represented by the green "breadcrumb".

Appearance and Movement

Motion capture devices

Shape analysis, registration, and segmentation of movement data

[2-MSC15] Dynamic feature points detected by our AniM-DoG framework are illustrated on a number of selected frames of animated meshes. The color of a sphere represents the temporal scale (from blue to red) of the feature point, and the radius of the sphere indicates the spatial scale.

Given a pair of animated meshes exhibiting semantically similar motion, we compute a sparse set of feature points on each mesh and compute spatial correspondences among them so that points with similar motion behavior are put in correspondence.

3D scanning and appearence digitization devices

Short range structured light scanner

Mid range time of flight laser scanner

Photography gears

3D Reconstruction of digitized objects (Détail)

Pipeline for reconstructing 3D objects from digitization data

Appearance reconstruction

Pipeline for the texturing of digitized 3D models from a set of pictures

Bear statue, cathedral of Strasbourg. From left: picture, 3D model reconstructed after geometry acquisition (35M points), textured 3D model reconstructed after appearance acquisition (55 pictures).

Bull statue, cathedral of Strasbourg. From left: picture, 3D model reconstructed after geometry acquisition (22M points), textured 3D model reconstructed after appearance acquisition (28 pictures).

Digital copies of three Dogon masks. From left: adone mask (antelope), kanaga mask, bird mask with a dege at the top of it.

Digital copy of a Hogon cup. Left-hand side: the cup fully assembled; right-hand side: each single piece presented separately.

Digital copies of two dege (female figurines).

Comparison between colour texture and light field. Reflections improve realism and offer a better understanding on the nature of the materials the object is made of.

Dragon. Geometry: 18.2M triangles. Texture: light field.

Mask1. Geometry: 7.7M triangles. Texture: light field.

Mask2. Geometry: 8.7M triangles. Texture: colour.

[2-VSGL13] Starting from a set of photos obtained from hand-held shooting, a virtual representation of the appearance of an object is reconstructed. This appearance especially encodes specular effects.