抄録
Preliminary investigation on users' performance requirements to the sensors onboard Japanese Earth Resources Satellite (JERS-1) was performed using image data obtained in the initial evaluation stage. JERS-1 carries two observation sensors; Synthetic Aperture Radar (SAR) and Optical Sensor (OPS). The SAR uses L-band microwave with an off-nadir angle of 35 degrees. Compared with the SAR image obtained by European Remote Sensing Satellite (EERS-1) with an off-nadir angle of 23 degrees, JERS-1 SAR images have much smaller topographic distortions such as layover and fore-shortening that make photogeologic interpretation very difficult. The JERS-1 images of L-band exhibit a better capability to discriminate vegetation types compared with the C-band EERS-1 SAR and X-band airborne SAR images. Topographic texture patterns on the JERS-1 SAR images were quite useful to distinguish lithologic units.
The OPS has better ground resolution than LANDSAT TM and thus allows us more detailed surface observation. In the case of the normal gain setting, DN mean and deviation of OPS image data were small, because of six bits quantization and the large maximum input radiamce, which was chosen not to be saturated at even very bright targets. On the other hand, saturation occurs at bright targets in a few bands with low gain setting. Considering these situations, flexible and complex operation with frequent gain changes is highly desired. The SWIR data is expected to be useful for lithologic mapping but shows high interband correlation as expected. It is necessary to employ techniques to enhance spectral response patterns such as the decorrelation stretching and spectral index methods.
