Use of a wide angle CCD line camera for BRDF measurements

In order to determine the Bi-directional Reflectance Distribution Function (BRDF) of natural surfaces a CCD line camera is used. This allows measureme nts under natural conditions with a high azimuth and zenith angular resolut ion in a short time. The CCD line spans a field of view of 80 degrees as th e zenith angle range. For covering the azimuth range, the camera is mounted on a rotating device and an extendible boom provides an aerial platform. T his set up allows the measurement of the [almost] complete reflectance dist ribution of the surface below the camera for the 30-s rotation period of th e camera. The camera used for this set up is the wide angle airborne camera (WAAC), which was developed at the DLR for airborne stereo imaging purpose s, This paper presents the radiometric calibration of the system and shows the initial results of our approach in measuring the BRDF with high angular resolution for a short period. (C) 2000 Elsevier Science B.V. All rights r eserved.