Deflectometry & Surface reconstruction

1. Project presentation

Holo3 is a technology transfer center, located in located in St Louis ( Alsace, France ) specializing into optical methods and imaging. Their main activities are to develop and make available to industries optical ressources on different forms, such as feasibility studies, tailored services with their own equipments or specific measure method supplies.

Among all their activities stand Polymap, a device born from the collaboration between Holo3 and the Institut Charles Sadron ( Strasbourg, France ). It can be used to measure local slopes of a surface, by using deflectrometry principle, and reconstruct it in 3D. It also have the capacity, as a result of its high sensibility, to measure prints on the study surface, about the micron size. Furthermore, the measures are done in a short time laps, without any specific preparations to do.


The project present in this document is the direct development of an previous internship with the Master CSMI realised in 2015. The main goal consists of reconstructing, from the slopes obtained by the Polymap device, the associated surface with the Finite Element method. At this main task,we want to add the possibility to take in account initial conditions, height mean of the surface for example, to work on an irregular mesh, due to camera deformations, or to exclude automatically areas with non compliant, or even nonexistent, data.

2. Project roadmap

During this project, our main objectives are as following :

  • Check the old codes, written by B. Vanthong, and determine what has benne done and what and how we can improve these to gain execution time

  • Port the application on Windows OS ( or at least allow to launch it at distance from a Windows computer )

  • Create a serial control application, that will reproduce the actual surface reconstruction for N cases and optimize for time execution

  • Implement the Levelset method, in order to detect problematic areas and supress them from the resolution.

  • Explore the Non-linear version of the surface reconstruction problem, that taken in account the cameras lenses caracteristics and the deformation resulting from them.