(DSLR) Cameras
Optimizing Radiometric Fidelity to Enhance Aerial Image Change Detection Utilizing Digital Single Lens Reflex (DSLR) Cameras Andrew D. Kerr and Douglas A. Stow Abstract Our objectives are to analyze the radiometric characteris- benefits of replicating solar ephemeris (Coulter et al., 2012, tics and best practices for maximizing radiometric fidel- Ahrends et al., 2008), specific shutter and aperture settings ity of digital single lens reflex (DSLR) cameras for aerial (Ahrends et al., 2008, Lebourgeois et al., 2008), using RAW image-based change detection. Control settings, exposure files (Deanet al., 2000, Coulter et al., 2012, Ahrends et al., values, white balance, light metering, ISO, and lens aper- 2008, Lebourgeois et al., 2008), vignetting abatement (Dean ture are evaluated for several bi-temporal imagery datasets. et al., 2000), and maintaining intra-frame white balance (WB) These variables are compared for their effects on dynamic consistency (Richardson et al., 2009, Levin et al., 2005). range, intra-frame brightness variation, acuity, temporal Through this study we seek to identify and determine how consistency, and detectability of simulated cracks. Test- to compensate and account for, the photometric aspects of im- ing was conducted from a terrestrial, rather than airborne age capture and postprocessing with DSLR cameras, to achieve platform, due to the large number of images collected, and high radiometric fidelity within and between digital multi- to minimize inter-image misregistration. Results point to temporal images. The overall goal is to minimize the effects of exposure biases in the range of −0.7 or −0.3EV (i.e., slightly these factors on the radiometric consistency of multi-temporal less than the auto-exposure selected levels) being preferable images, inter-frame brightness, and capture of images with for change detection and noise minimization, by achiev- high acuity and dynamic range.
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