To increase the accuracy of 3D rockfall trajectography analysis, we propose a tool that uses point cloud data directly as the input topography for 3D rockfall modeling as opposed to gridded-Digital Elevation Models (DEM) that are used in current softwares. The goal is to take into account overhanging slopes and other irregular features that are smoothed or suppressed in the rasterizing/gridding process. Point clouds acquired obliquely to a rock cliff, either by laser scanner or photogrammetry, accurately represent its topography and they are now used for structural analysis, volume calculation, change detection and displacement analysis. We propose a rockfall simulation algorithm that uses a vegetation-free point cloud as the topography input. It enhances the analysis: for example, an overhanging slope can be used as a rockfall source. A future research avenue of using point clouds instead of a gridded-DEM is the study of the impact of vegetation on rockfall travel.