|Qi, J. - USDA-ARS-USWCL, PHOENIX|
|Bryant, R. - USDA-ARS-USWCL, PHOENIX|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 19, 1998
Publication Date: N/A
Technical Abstract: Chemically-treated polyester tarps of large dimension (8 x 8m) have been used to provide a stable ground reference for calibration of images from airborne sensors. In this study, we addressed the issues of tarp calibration and tarp size relative to pixel resolution for tarps of nominal reflectances 0.04, 0.08, 0.32, 0.48, and 0.64. Results showed that the tarps of all reflectances were highly non-lambertian, and the calibration equations varied with both spectral wavelength and tarp reflectance. The tarp properties were relatively consistent in the visible and near-infrared spectrum, but were less predictable in the shortwave-infrared. Additional tests showed that nominal tarp reflectance degraded with both time and tarp dirtiness. For field deployment with airborne cameras, a pixel resolution to tarp size ratio 1:8 was recommended as a minimum to avoid the contamination of reflectances at the tarp edges.