| Popis: |
It has been found that a close relationship exists between the spectral reflectance and the health as well as the productivity of soybean canopies. Basing on this property, a remote sensing method was used to assess the plant productivity and health, which was able to cover a large area simultaneously. In this project, aerial images and reflectance measurements were obtained from two soybean fields located in Story Country, Iowa during summer 2000 and 2001. Aerial image were taken on both infrared band and color band. An eight-band radiometer was used to obtain the reflectance reading at ground level, which ranged from 460-nm to 810-nm. A study on aerial-radiometer data relation for two continuous years was carried out. The reflectance measurement from radiometer served as ground truth. Also, the calibration procedure for aerial image was applied. Because the atmospheric distortion became more pronounced when the aerial image was taken at higher altitude. Scattering and absorption will affect the image intensity which indirectly affect our analysis. The red, green and blue ground cloths were put beside the fields when the aerial image was taken. They are used as references to evaluate color distortion in the red, blue and green bands respectively. |
