Camera preparation and performance for 3D luminance mapping of road environments

Abstract

Road lighting measurements are executed with stationary imaging luminance photometry. In these measurements, a digital camera is utilized to create 2D luminance data maps of the scenery. We consider the third dimension to be a meaningful advancement for luminance data presentation and analysis. Hence, we present the preparation for a digital camera in order to use it as an imaging luminance photometer combined with a laser scanning system. The target area of use for our measuring system is the night-time road environment. We assessed the limiting factors when integrating luminance photometry into laser scanning systems. We achieved the initial luminance data and 3D point cloud integration for terrestrial laser scanning (TLS) and mobile laser scanning (MLS) systems. In stationary luminance measurements, the target luminance range was achieved. For mobile measurements, the target luminance range was compromised. The mobile measurement luminance range was limited because a long exposure time could not be used. Ashort exposure time was compensated for by increasing the sensor sensitivity, which reduced the signal-to-noise ratio. In mobile measurements, the luminance range can be extended towards the low end only by reducing the movement velocity or by accepting more motion blur in the measurements.