Preliminary Comparison of the Multispectral Cameras Onboard UAV Platform for Environment Monitoring

Unmanned aerial vehicle (UAV) provides an alternative way to collect data conveniently, when corresponding sensor (s) is (are) equipped onboard. In this paper, two multispectral cameras were compared mainly based on simulated channel reflectance, which covered visible (i.e., Blue, Green, and Red), near infrared (NIR), and red-edge (RE) regions. The preliminary investigation shows the between-sensor differences in sensor settings, the related differences in channel reflectance, and in the derived vegetation indices. The between-sensor differences in channel reflectance vary with channels. Compared with the Green and NIR channels, the RE and Red channels show more obvious between-sensor difference, which contributes significantly to the differences in the derived vegetation indices. The between-sensor differences in the RE channel are required to be eliminated, because the RE reflectance and the derived indices correspondingly are important in modeling biophysical parameters. Case study shows that the between-sensor differences of vegetation indices were generally more obvious than the reflectance differences of individual channels. Damage assessment for plant over flooded areas was readily done with the help of vegetation indices. Accordingly, the between-sensor differences are likely significant in practical applications. In conclusion, the importance to make consistency among data collections by different sensors (i.e., onboard UAV) is highlighted, and an effective way for between-sensor transformation is required in further investigations.