Structural change detection by direct 3D model comparison

: Tracking the structural evolution of a site has important fields of application, ranging from documenting the excavation progress during an archaeological campaign, to hydro-geological monitoring. In this paper, we propose a simple yet effective method that exploits vision-based reconstructed 3D models of a time-changing environment to automatically detect any geometric changes in it. Changes are localized by direct comparison of time-separated 3D point clouds according to a majority voting scheme based on three criteria that compare density, shape and distribution of 3D points. As a by-product, a 4D (space + time) map of the scene can also be generated and visualized. Experimental results obtained with two distinct scenarios (object removal and object displacement) provide both a qualitative and quantitative insight into method accuracy.