Ground-look Radiometric Calibration Approaches for Remote Sensing Imagers in the Solar Reflective

Since the early 1990s, the availability of remote sensing imagery in the solar reflective (400 to 2500 nm) has seen a dramatic increase. Airborneand satellite-based sensors now cover this spectral range with a variety of spectral resolutions (from the multispectral to hyperspectral) and spatial resolutions ranging from better than 0.3 m for some airborne systems (and better than 1 m for satellite-based sensors) to 1 km. A critical component to the successful use of data from these systems is the pre-flight and in-flight radiometric calibration of the sensors. This paper provides an overview of currently-used calibration approaches for the inflight calibration using terrestrially-based sites. These methods are colloquially known as vicarious calibration and, alternatively referred to as radiance validations. This discussion focuses on reflectance-based and cross-comparison approaches that can be used at a range of spatial and spectral resolutions. An example of the application of the in-flight and pre-flight calibrations is demonstrated showing results from ALI, ASTER, Hyperion, ETM+, Ikonos, and MODIS.