12 months post-doctoral research position

«3D reconstruction of liquid specular object»

Contacts :

Olivier Aubreton

Le2i (UMR CNRS 5158)

Pierre Sallamand

LICB (UMR CNRS 5209)

email :

Alexandre Mathieu

LICB (UMR CNRS 5209)

The goal of this postdoctoral position is to develop some solutions in order to obtain 2D and 3D reconstruction of mirroring objects in case of specular and liquid moving surface such as the melt pool obtained by laser welding process.

The 3D reconstruction by artificial vision has been often studied since the last decade. Classical approaches by active scanning, (by projecting a light pattern), work very well on Lambertian surfaces but are not suitable for specular surfaces because they reflect light as a mirror.

We can find in the literature some approaches which have been proposed to reconstruct the 3D shape of mirroring surfaces (1). As an example, Deflectometry or Shape From Distortion approaches seems to be more appropriated to this problem (2).

In this research program we propose to study the possibility to apply one of these methods in order to obtain 2D and 3D geometrical information of the surface. The acquisition setup is based on a hight speed camera installed on the welding system. The first step is to realise some video acquisitions during the welding process and develop some image processing tools to determine 2D geometrical informations (length and width) of the melt pool. In a second step some experiments will be realise in order to test Deflectometry in order to obtain 3D reconstruction of the surface.

This study is part of the ANR Project SISHYFE (“SImulation du Soudage HYbride en Forte Epaisseur “: Simulation of hybrid welding in case of thick sheets). This project started 1 year ago and is managed by the team Laser and Treatments of Materials from the Laboratory ICB (3) (UMR 5209). The team Vision 3D of the laboratory Le2I (UMR 5158) (4) is the partner of the LTM Team for this part of the project.

(1) “State of the Art in Transparent and Specular Object Reconstruction”, I. Ihrke, K. N. Kutulakos, H. P. A. Lensch, M. Magnor, and W. Heidrich, in STAR Proceedings of eurographics, pp. 87–108 (2008)

(2) « 3D Acquisition of Mirroring Objects» M. Tarini, H. P. A Lensh., M. Goesele, H.P. Seidel. Graphical Models 67, 4 (2005), 233–259.

(3)

(4)

Keywords : Image processing, Computer Vision, Machine vision, Deflectometry ,3D reconstruction

Practical informations :

Salary range: ≥ 35,000 and < 45,000€ annual gross

LEII and LTM Teams are based in “Le Creusot” (University of Burgundy antenna)

(by High Speed TGV Train : 1h20 from Paris / 40 min from Lyon):

a single room flat for rent is about 300 €, and 600 € for a house with garden