Quantitative remote sensing with off-the -shelf instruments on a small UAV

Kurzfassung

The Stuttgarter Adler is a small, remote controlled aircraft which was designed as a platform for small-scale remote sensing from 100 to 300 meters above the ground. Equipped with off-the-shelf cameras and a spectrometer it offers a flexible and inexpensive means to collect detailed remote sensing data in the visible and near infrared as well as the thermal infrared range. This paper shows the capability of the platform with its VIS/NIR and thermal instrumentation to acquire remote sensing data of high resolution. A number of calibration methods have been adapted and procedures have been developed for this purpose. Digital numbers of the VIS/NIR cameras and of the spectrometer with the current calibration is better than 7 percent of spectral radiance. Relative errors during calibration caused by noise range from 1 percent for the spectrometer to 2 percent for the NIR-camera. In order to derive reflectance values, the atmospheric properties are measured during image acquisition and used as input to numerical radiation transport to calculate irradiance. For geometric processing and referencing, recent developments in photogrammetric methods, based on image matching and robust bundle adjustment, have been adapted and applied to the data. Image data can be referenced with an accuracy of 0.02 to 0.04 meters. First steps of quality evaluation have been taken for VIS/NIR airborne data by comparison between the instruments and calculation of reflectance.