Microsoft has recently released a mixed reality headset called HoloLens. This semi-transparent visor headset allows the user who wears it to view the projection of 3D virtual objects placed in its real environment. The user can also grasp these 3D objects, which can also interact with each other. The framework of this new technology taking into account this physical approach (interactions, collisions) is called mixed reality . We had the opportunity to digitally transform a conventional nutrition workshop for patients waiting for bariatric surgery by designing a mixed reality software using the HoloLens headset. This software is called HOLO_NUTRI. In this paper, we present this software and its assessment (acceptance of this technology) by a cohort of thirty patients.

Ma and Sonka proposed a fully parallel 3D thinning algorithm which does not always preserve topology. We propose an algorithm based on P-simple points which automatically corrects Ma and Sonka's algorithm. As far as we know, our algorithm is the only fully parallel curve thinning algorithm which preserves topology.

We describe the calibration of a catadioptric omnidirectional video projection system that adjusts its projection to the geometry of any scene by means of a rotating camera. Correction of geometric distortions requires 3D reconstruction of the scene. A camera is used to detect projected point features and calibration is performed in three successive steps: precalibration of camera assuming pure rotation, precalibration of catadioptric projector under central approximation and calibration of the global system, by minimizing the squared distance between the reflected and perceived rays, and by relaxing previous constraints, to refine values of extrinsic parameters. Simulation is used to validate estimated values of parameters and distance between the 3D reconstruction of the projection room and its expected geometry. Influence of noise in detected point coordinates is studied and preliminary results for the reconstruction and projection in real conditions are reported.