Various video multispectral systems were investigated in respect to their advantages, disadavantages and their costs for monitoring the water environment. It was found that line filter video multispectral systems present various advantages compared with conventional video multispectral systems. Such a line filter or Fabry-Perot-filter was fixed in front of a video camera lens by moving the filter to and fro with a certain frequency according to the required ground speed for airborne operations. The imaging spot on the filter was selected in such a way that it cuts out a spectral width of 10 nm for each channel ranging from 400 to 790 nm with 40 bands. A LED at the end of the filter serves as a calibration light spot of 370 nm which is the maximum of the sky irradiance. Its known radiance is recorded after each channel sequence on the video camera CCD. With this arrangement the images can be obtained, digitized, calibrated, post- and image processed.
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