Pixels to pyrometrics: Uncrewed aircraft systems to evaluate and monitor prescribed fire

O'Neill, Leo (2023) Pixels to pyrometrics: Uncrewed aircraft systems to evaluate and monitor prescribed fire. Masters thesis, Northern Arizona University.

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Abstract

Prescribed fire is vital for fuel reduction and ecological restoration, though the effectiveness and fine-scale interactions are poorly understood. Uncrewed aircraft systems (UAS) coupled with infrared (IR) sensors present new opportunities for advancing prescribed fire science and evaluation. Here, I present three main chapters to introduce, research, and synthesize the concept of UAS-IR derived pyrometrics. The literature review chapter covers UAS for ecological monitoring, focusing on forest biometrics and fire pyrometrics. I describe the limitations of each and present a framework for understanding how these innovative technologies can improve our understanding of complex biophysical properties. As UAS-derived measurement accuracies improve, it is important to highlight the collaborative nature of these challenges; interdisciplinary collaboration will undoubtedly play a crucial role in future management practices. In the research chapter, I develop methods for processing UAS-IR imagery into spatially explicit pyrometrics: measurements of fuel consumption, rate of spread, and residence time to quantitatively measure three prescribed fires. I collected nadir IR imagery continuously (0.2 Hz) over a fixed area at three prescribed burns and one experimental calibration burn, capturing fire progression and post-frontal combustion for a total of 16 hours. Stabilizing the images with an Enhanced Correlation Coefficient model was robust against large perspective shifts and produced image stacks with less than one meter drift. UAS-IR fuel consumption correlated strongly with weight-based measurements of ten experimental burn plots, validating our approach to estimating consumption with a cost-effective UAS-IR sensor (R2 = 0.99). UAS-IR pyrometrics of the three prescribed burns agreed with visual observations and showcased significant variability between each of the three fires. These findings demonstrate UAS-IR pyrometrics are an accurate approach to monitoring fire behavior and effects at spatiotemporal scales required to characterize prescribed fire. Additional research is needed to validate and compare against numerical, field-sampled standards. We noted that two of the three prescribed fires likely achieved consumption objectives, though objectives were often broad, unrealistic, and/or did not directly pertain to measured pyrometrics. Lastly, I synthesized the findings into a fact sheet tailored for fire and fuel managers. UAS-IR monitoring of prescribed fires is an accurate, efficient method of measuring fire. Refined fire monitoring coupled with refined objectives will be pivotal in informing fire management of best practices, justifying the use of prescribed fire, and providing quantitative feedback in an environment saturated with uncertainty.

Item Type:	Thesis (Masters)
Publisher’s Statement:	© Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords:	fire behavior; fire monitoring; fire radiative energy (FRE); fire radiative power (FRP); fire rate of spread; fuel; Uncrewed aircraft systems; Prescribed burning; Forest management
Subjects:	S Agriculture > SD Forestry
NAU Depositing Author Academic Status:	Student
Department/Unit:	Graduate College > Theses and Dissertations College of the Environment, Forestry, and Natural Sciences > School of Forestry
Date Deposited:	24 Jul 2026 18:27
Last Modified:	24 Jul 2026 18:27
URI:	https://openknowledge.nau.edu/id/eprint/6315

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