VISIBILITY ANALYSES USING 3D URBAN MODELS GENERATED BY LOW-COST MULTI-SENSOR APPROACHES

The conditions of visibility of a user moving through an outdoor or indoor environment affect his safety. In both environments it is fundamental to guarantee a sufficient visibility in order to avoid possible collisions. The available sight distance (ASD) is that part of the roadway ahead which is visible to the driver and should be of sufficient length to allow a vehicle to stop before colliding with a stationary object. For indoor environment, in particular for public buildings it is necessary to identify the easiest paths to follow in order to ensure a fast and efficient escape route in emergency cases. The ways in which a person is able to move within the environment are strongly influenced by the space he is able to see in front of himself and by the position of some objects. Today, the estimation of the ASD and the visible space are still carried out on digital terrain models (DTM) or 2D maps, without considering the effects of sight obstructions. The aim of this research work is to propose automatic methods for the visibility analysis, that take into account the dynamism of the individual and the environment. Since it is essential to have a 3D model on which to base the analyses, the first part of the research, will be focused on the investigation of rapid, flexible and low-cost survey methods for collecting 3D information of environment at different scales. A goal of this work is related to evaluate the possibility to realize and to use low-cost mobile mapping systems (MMSs) as an alternative for obtaining 3D information of urban infrastructure. The second part of the activities aimed at the development of automatic procedures to perform visibility analysis exploiting the obtained 3D model. Different tools for the visibility analysis and the estimation of the ASD from a driver’s point of view were compiled and tested, taking into account the dynamicity of the movement. Finally, a procedure for quantitatively assessing the complexity of a known path to follow in emergency cases inside of public buildings was proposed.