Radiometric corrections of the vignetting effect in aerial digital images

• Main Authors: Andrés L. G. Jaime, Rubens A. C. Lamparelli, Jansle V. Rocha
• Format: Article
• Language: English
• Published: Universidade Federal de Uberlândia 2004-07-01
• Series: Revista Brasileira de Cartografia
• Subjects: Yield estimate; Remote Sensing; Vignetting effect.
• Online Access: http://www.rbc.ufrj.br/_pdf_56_2004/56_1_07.pdf

Monitoring agriculture cultures by aerial remote sensing present high potential of application. Despite of that potential, some problems still have been detected. One of them is the vignetting effect. This phenomenon introduces error in DN as far away as geometric image center the target is, according to the cos4Theta law. To study this effect it was adopted the procedure that computes Equation - Equação. If these values increase with the distances from images geometric center then the vignetting effect increases proportionally. The study was carried out analyzing the DN of white plate targets in aerial images in two dates 02/11/2001 and 11/04/2002. The white plate targets were distributed in the field and could be seen around the images geometric center, in different distances. In the aerial images the DN from the plates were extracted according to the cos4Theta law and compared to several distances in conformity to Equation - Equação. The results showed that the effect was observed in the first (02/11/2001) images, but not in later (11/04/2002) images. That difference can be explained by the different atmospheric haze and sensor-illumination source geometry. On the other hand when the experiment was performed at ground level the vignetting effect was identified. Therefore the effect exists and can be modeled.