The extraction of a 3D topological map from an Oriented Boundary Graph can be needed to refine a 3D Split and Merge segmentation using topological information such as the Euler characteristic of regions. A presegmentation could thus be efficiently obtained using a light structuring model, before proceeding to the extraction of more information on some regions of interest. In this paper, we present the topological map extraction algorithm which allows to reconstruct locally a set of regions from the Oriented Boundary Graph. A comparison of the two models is also presented.