Comparison of reflective band (Vis, NIR, SWIR, eSWIR) performance in daytime reduced illumination conditions

Lindsey Wiley, Richard Cavanaugh, Joshua Follansbee, Derek Burrell, Robert Grimming, Rich Pimpinella, Jeff Voss, Orges Furxhi, Ronald Driggers

Research output: Contribution to journalArticlepeer-review

Abstract

Daytime low-light conditions such as overcast, dawn, and dusk pose a challenge for object discrimination in the reflective bands, where the majority of illumination comes from reflected solar light. In reduced-illumination conditions, the sensor signal-to-noise ratio can suffer, inhibiting range performance for detecting, recognizing, and identifying objects of interest. This performance reduction is more apparent in the longer wavelengths where there is less solar light. Range performance models show a strong dependence on cloud type and thickness, as well as time of day across the reflective wavebands. Through an experimental and theoretical analysis of a passive sensitivity- and resolution-matched testbed, we compare Vis (0.4–0.7 µm), NIR (0.7–1 µm), SWIR (1–1.7 µm), and eSWIR (2–2.5 µm) to assess the limiting cases in which reduced illumination inhibits range performance. The time during dawn and dusk is brief yet does show significant range performance reduction for SWIR and eSWIR. Under heavy cloud cover, eSWIR suffers the most at range due to a low signal-to-noise ratio. In cases of severe reduction in illumination, we propose utilizing active illumination or the emissive component of eSWIR to improve the signal-to-noise ratio for various discrimination tasks.

Original languageEnglish (US)
Pages (from-to)8316-8326
Number of pages11
JournalApplied optics
Volume62
Issue number31
DOIs
StatePublished - 2023

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Engineering (miscellaneous)
  • Electrical and Electronic Engineering

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