Speaker: Neus Sabater, Caltech
Title: Reliability and accuracy in stereovision (Joint work with J.-M. Morel and A. Almansa)
Abstract:
This work is a contribution to stereovision written in the
framework of the MISS (Mathematics for Stereoscopic Space Imaging) project
launched by CNES (French Space Agency). This project has the ambitious goal
to model a stereo satellite, using two almost simultaneous views of the
Earth with small baseline in urban areas. Its main goal is to get an
automatic chain of urban reconstruction at high resolution from such pairs
of views. The project faces fundamental problems that our work aims at
solving.
The first problem is the rejection of matches that could occur just by chance, particularly in shadows or occlusions, and the rejection of moving objects (vehicles, pedestrians, etc.). In this work we have proposed a method for rejecting false matches based on the "a contrario" methodology. The mathematical consistency of this rejection method will be shown and it will be validated. The reliable accepted matches reach a 40% to 90% density in the tested pairs.
The second issue is the accuracy. Indeed, the type of considered stereoscopy requires a very low baseline between the two views, which are visually almost identical. To get a proper relief, an extremely accurate shift must be estimated, and the noise level that allows this accuracy must be calibrated. In this work a subpixel disparity estimation method is proposed, which will be proved optimal by experimental and mathematical arguments.