Identification of road surface conditions based on laser scanning

Detection water and aqueous land hazards in outdoor navigation is a big challenge in unknown outdoor environment. Advantages of laser scanning are encouraging, firstly due to its distinguished detection capacity at night and less quantity of data. It was found by experiments that there was no evident changing trend of laser remission with the increase of color density in water, no matter green, red, or dark blue. These colored water shared common feature of weak mirror-deflection with pure water. However, remission of black water surface dropped linearly approximately with the increase of color density, and strong mirror-deflection was observed. Experiments also indicated that water turbidity had great effect on both remission and mirror-deflection, and there was significant positive correlation between laser remission and the soil moisture content. These phenomena could be explained with twice reflected pulse property of laser range finder and optical property of water-air interface in laser scanning. Based on the experiment results, methods to distinguish pure or turbid water surface from land and to distinguish hazard aqueous land from safe dry land in natural scene were put forward.