Updated results of calibration and validation of PRISM and AVNIR-2
Takeo Tadono(1), Masanobu Shimada(1), Junichi Takaku(2) and Sachi Kawamoto(2)
(1) JAXA, 2-1-1, Sengen,, 305-8505, Japan
(2) Remote Sensing Technology Center of Japan, Roppongi First Build., 1-9-9, Roppongi, Minato-ku, 106-0032, Japan
The Advanced Land Observing Satellite (ALOS, nicknamed “Daichi”) was successfully launched on January 24, 2006, and continuously operating very well. This paper describes updated results of calibration, validation and image quality evaluation for two ALOS optical sensors i.e. the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) and the Advance Visible and Near Infrared Radiometer type-2 (AVNIR-2). PRISM consists of three independent panchromatic radiometers and is using to derive a digital surface model (DSM) with high spatial resolution, which is an objective of the ALOS mission.
The preliminary results of calibration, validation and image quality evaluations of PRISM and AVNIR-2 have been presented. At that time, we analyzed data acquired during the initial mission check (IMC) and the initial calibration phase (ICP), which was spent 9 months after the launch and beginning of operational phase until 2007. As the results of beginning of operational phase as of September 2007, the sensor characterizations have been evaluated, and the radiometric accuracies of both PRISM and AVNIR-2 were almost sufficient, and geometric accuracies of them were also good. However, accuracy degradations with a time after launch are founded. Therefore, accuracy assessments are continuously carried out as the operational calibration.
We are also developing DSM and ortho-rectified image generation software as a part of validation. Those products are defined as a high level product in JAXA. Thus, geometric calibration is important in generating a highly accurate DSM with stereo pair images of PRISM. Relative radiometric calibration is carried out using acquired images over homogeneous targets such as ocean, deserts, ice and snow areas, and nighttime observation. The absolute radiometric calibration is applying with the cross-calibration method using calibrated satellite images (e.g. MODIS aboard Terra and Aqua satellites, ASTER, and SPOT-5). In this paper, the updated results of calibration and validation as well as stabilities of sensor characterization will be given.