## Journées “Informatique et Géométrie” 2006

I had the pleasure to give a talk at the Days “Data processing and Geometry” (this is what google makes from the title) at Lyon the first two days of june.

It is quite an experience to attend a scientific meeting when having only a faint idea of the language (the spoken one, not the scientific) :-). While lasting only two days the conference covered quite a widespread range of topics. Especially interesting to me was some introduction into the design of the CGAL library — a collection of robust and efficient algorithms for geometry presented by Sylvain Pion and Raphaelle Chaine. An other interesting talk was from Alain Daurat on discrete tomography of convex sets. The question here is about algorithms that allow the reconstruction of the shape given the sample values along some finite number of directions (and what are the conditions on the choice of directions to ensure a reconstruction is possible). The complete reconstruction of any set given sample data along any discrete straight line was turned into a game by us recently. Many of the talks dealt with (re)construction of shapes: like arithmetic definition for Bresenham circles (Jean-Luc Toutant), a modeler based on the topology of discrete objects (Alain Daurat), or an algorithm for implicit surfaces (Christophe Raffalli)

I myself tried to draw the attention to the Berlin grown software jReality and oorange.