Utilizing a Consumer-Grade Camera System to Quantify Surface Reflectance

Authors

Joseph J. Lehnert, University of Nebraska - LincolnFollow

First Advisor

Arthur I. Zygielbaum

Date of this Version

Summer 8-2-2017

Document Type

Article

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Arts, Major: Geography, Under the Supervision of Professor Arthur I. Zygielbaum. Lincoln, Nebraska: August, 2017

Copyright (c) 2017 Joseph J. Lehnert

Abstract

Consumer-grade camera systems are often employed in aerial remote sensing to provide insight into patterns and processes of interest to science and industry, a trend that has largely been encouraged by the rapid growth of the small unmanned aircraft system (sUAS) industry. However, little research exists on the ability of these systems to accurately measure surface reflectance in specific wavebands, a crucial consideration for many remote sensing applications. This research was conducted on the premise that with proper equipment and calibration techniques consumer-grade cameras would be capable of accurately measuring surface reflectance in user-defined wavebands of interest. A stereo-pair, Fujifilm IS Pro camera system was constructed and fitted with specialized filters to isolate wavebands related to vegetative features of interest. Multi-colored foam swatches and turf grass nitrogen calibration plots were imaged in a number of environments. Images were subsequently processed using linear calculation, vignette correction, and reflectance adjustment. Image reflectance values were then compared to Ocean Optics 2000+ reflectance captured at the same location and the coefficient of determination (r²) was used to determine the degree of similarity between the two systems. Turf plot reflectance was used to calculate the red edge Chlorophyll Index (CI_{red edge}) from both instruments and these values were also compared using r². Foam swatch comparisons resulted in r² = 0.97 or better for all lens/filter combinations, suggesting consumer-grade cameras are capable of accurate measures of reflectance. CI_{red edge} comparisons yielded daily averaged r² values of 0.86 and 0.70, depending on the lens/filter combination used, suggesting these systems could potentially be utilized in a number of advanced remote sensing roles.

Advisor: Arthur I. Zygielbaum