Absolute calibration over bi-reflectance target for airborne and spaceborne cameras

This paper deals with the in-the-field absolute calibration of airborne or spaceborne passive optical sensors in the reflective domain. One way to proceed is to image an area whose radiance is known and to have information about atmosphere. Usually, in order to limit the sensitivity to unwell-known parameters, areas are chosen uniform, large, flat, with stability of their reflectance and their atmospheric context. This leads for spaceborne sensors to desert areas, African deserts or Antarctica for instance. For high resolution sensors such as airborne sensors, it is necessary to find closer areas. This paper presents a calibration method relying on a dark and bright target. The use of two reflectances simplifies the assessment of the radiance entering in the camera and probably reduces the sensitivity to the environment of the target. This method is tested for the ONERA airborne camera named PELICAN.