Infrared Reflectance Requirements of the Surrogate Grass from Various Viewing Angles

To minimize the risk of run-off-road collision, new technology in Advanced Driver Assistive System (ADAS), called Road Departure Mitigation Systems (RDMS), is being introduced recently. Most of the RDMS rely on clear lane markings to detect road departure events using the camera for decision-making and control actions. However, many roadsides do not have lane markings or clear lane markings, especially in some rural and residential areas. The absence of lane markings forces RDMS to observe roadside objects and road edge and use them as a reference to determine whether a roadway departure incident is happening or not. To support and guide for developing and evaluating RDMS, a testing environment with representative road edges needs to be established. Since the grass road edge is the most common in the US, the grass road edge should be included in a testing environment. This paper studied the spectral features of various kinds of grasses as well as determined the reflectance range of these grass types in different measurement conditions with LiDAR. The long-term goal of this research was to develop surrogate roadside grass samples that have representative spectral characteristics of the real roadside grass as measured by automotive LIDAR. The results from this study indicate that LiDAR operation conditions can be mimicked in a lab setup with an ASD spectrometer. The upper and lower limits of infrared (IR) reflectance of different grasses at 0-70° viewing angles have been specified. These measurement results can be utilized to develop roadside surrogate grass for evaluating RDMS.