Geometric Modeling, Simulation and Interaction

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Geometric Modeling, Simulation and Interaction

Objectives / Challenges

The main objective is to improve the quality in terms of efficiency and robustness of geometric modeling and simulation operations. To achieve this goal, we operate our topological models based on combinatorial maps that facilitate the operations of geometric modeling design through their generic in terms of size and type of cell, and thanks also to the separation of the topology and the embedding of objects which is the basic concept.

Participants

• Two Professors : Dominique Bechmann et David Cazier
• One Senior Researcher : Stephane Cotin
• Three Assitant professors : Antonio Capobianco, Jérôme Grosjean et Pierre Kraemer
• Two Research engineers : Thierry Blandet et Sylvain Thery
• 5 PhD : Sabah Boustila (Project CIMBEES from Dec. 2012 to Sept. 2015 (PhD thesis defended on May 25, 2016)), Christoph Paulus (INRIA contract starting from January 2014), Thomas Pitiot (CNRS / Région Alsace doctoral contract from Oct. 2012 to Sept. 2015 (PhD thesis defended on December 17th, 2015)), Lionel Untereiner (UNISTRA doctoral contract from Oct. 2010 to Sept. 2013 (PhD thesis defended on November 8th, 2013)), Jonathan Wonner (Allocataire Normalien from January 2011 to Dec. 2013 (PhD thesis defended on October 8th, 2013)).

Results

Adaptative and multiresolution volumic model

A strong trend in geometric modeling is to use multiresolution to represent objects at different scales. We proposed a model quite original, combinatorial maps multiresolution model based on combinatorial maps. This work was extended with the thesis of Lionel Untereiner [8-UNTE13] in any dimension of meshes. We defined topological and geometric operators to first work on dimension 3 tetrahedral and hexahedral meshes, and more generally on arbitrary topologies with a multi-scale approach [3-UCB12, 2-UCB13].

If multiresolution representations are studied for long time for surfaces, multiresolution models supporting volumetric representations or greater dimension are very rare and limited to very specific applications. The development of generic models with multiresolution simplification operators, subdivision and refinement both topological and geometrical is a major issue in geometric modeling. This work was implemented in the modeling platform CGoGN [4-KUJT13]. An implicit representation, more compact, also has been proposed [2-UKCB15].

Détection des collisions dans des scènes en mouvement

Simulation de découpe en temps réel

Separation of degrees of freedom for manipulating objects

Our interaction concern is to improve the creation and interactive manipulation of digital objects. The hopes raised by the virtual reality in the beginning, was that the immersive environment would be likely to improve the perception of 3D objects. In fact, if stereoscopic vision provides a feeling of 3D, it makes them less accurate direct manipulation. Our goal has been to offer solutions that leverage these immersive environments.

We got convincing results for positioning and orientation tasks of an object through the separation of degrees of freedom (DOF) and the use of proprioception (awareness that one has to position its own body). We have shown that, contrary to the approach generally operated, based on maximum integration of the different DOF for such type of tasks, it is preferable to isolate the control of the dimensions if we require a significant level of accuracy in the final phase of the task. In consecration of this work, we have obtained a publication in the best international conference IEEE Virtual Reality VR'2011 [4-VCB11] where this year it was to be the only long accepted paper from a French laboratory.

Aids for selection of targets in immersive environements

As part of the thesis of Jonathan Wonner [8-Wonn13], we proposed three areas for improvement and help in the selection of immersive targets.

1. To locate a target with an indication of its orientation, the challenge is to give the user 3D direction information without visual overload. The original idea is to use a series of circles around an axis indicating a direction with a simple color code, the red-green direction giving the right direction. These circles are positioned on the surface of a sphere and thus seen as ellipses, depending on the orientation of the sphere and the point of view of the user. Integrated with a spherical pointer whose radius adapts to reach the nearest object, the analysis of experimental results showed that this selection technique [4-WGCB13] offers a credible alternative to the best technical support of the state of the art (3D arrow) for the localisation.

2. For selecting a target in dense environment, the key idea of an original technique of guidance, also coupled to the spherical pointer, is to offer dynamic branches along segments connecting the pointer to potential targets. The preset target is performed by applying multiple filters: distance filter, angular filter, the maximum number of target. The highlight of the 'Starfish' '4-http://icube-publis.unistra.fr/4-WGCB12 WGCB12 which clearly shows the interest and relevance of the method is that the error rate remains stable when increasing the density of the target in the immersive environment.

3. Finally, a new method of estimating the target based on the movement of the hand and specifically the control phase of the movement after the peak speed of movement of the hand, led to a prediction of the target, from the user selection gesture [5-WGCB11].

Facteur de perception des distances en environnement virtuel

Perspectives