Automatic 3D land register extraction from altimetric data in dense urban areas
Abstract
This work present an automatic algorithm that extract 3D land register from altimetric data in dense urban areas. Altimetry of a town is a data which is easily available yet difficult to exploit. For instance, we present here results on two kind of measurements : the first one consists in a Digital Elevation Model (DEM) built using a correlation algorithm and some optical data, while the second one consists in a DEM obtained by Laser measurments.Our main objective is to design an entirely automatic method that is able to deal with this kind of data in very dense urban areas.We thus focus on elementary shape extraction and propose an algorithm that extracts rectangular buildings. The result provided consists in a kind of vectorial land register map that can be used, for instance, to perform precise roof shape estimation.The proposed algorithm uses our previous work. Using a point process framework, we model towns as configuration of rectangles. An energy is defined, that takes into account both a low level information provided by the altimetry of the scene, and some geometric knowledge of the disposition of buildings in towns.The estimation is done by minimizing the energy using a simulated annealing. We use a MCMC sampler that is a combination of general Metropolis Hastings Green techniques and Geyer and Møller algorithm of sampling of point processes. We use some original proposition kernels, such as birth or death in a neighborhood and define the energy with respect to an inhomogeneous Poisson point process.We present results on real data provided by IGN (French Mapping Institute). Results were automatically obtained, on areas that are 200m by 200m large. These results consist in configurations of around 100 rectangles describing considered areas with an error of 15 missclassification.