Geocorrection of Airborne Mid-Wave Infrared Imagery for Mapping Wildfires without GPS or IMU.

Gabriela Ifimov,George Leblanc,Juan Pablo Arroyo-Mora,Madeline D Lee,Tomas Naprstek,Joshua M Johnston

doi:10.3390/s21093047

Abstract

The increase in annual wildfires in many areas of the world has triggered international efforts to deploy sensors on airborne and space platforms to map these events and understand their behaviour. During the summer of 2017, an airborne flight campaign acquired mid-wave infrared imagery over active wildfires in Northern Ontario, Canada. However, it suffered multiple position-based equipment issues, thus requiring a non-standard geocorrection methodology. This study presents the approach, which utilizes a two-step semi-automatic geocorrection process that outputs image mosaics from airborne infrared video input. The first step extracts individual video frames that are combined into orthoimages using an automatic image registration method. The second step involves the georeferencing of the imagery using pseudo-ground control points to a fixed coordinate systems. The output geocorrected datasets in units of radiance can then be used to derive fire products such as fire radiative power density (FRPD). Prior to the georeferencing process, the Root Mean Square Error (RMSE) associated with the imagery was greater than 200 m. After the georeferencing process was applied, an RMSE below 30 m was reported, and the computed FRPD estimations are within expected values across the literature. As such, this alternative geocorrection methodology successfully salvages an otherwise unusable dataset and can be adapted by other researchers that do not have access to accurate positional information for airborne infrared flight campaigns over wildfires.

Highlights

As wildfire events have increased in many areas of the world with catastrophic consequences [1,2,3,4], the ability to accurately monitor these events at different spatial and temporal scales is becoming a key concern and focus for governments around the globe [5,6,7]
Our study provides a novel geocorrection methodology for a case where GPS and Inertial Measurement Unit (IMU) airborne equipment malfunctions occurred during a 2017 airborne wildfire campaign collecting FLIR MWIR images
Based on the MWIR radiance method [11], our study shows fire radiative power density (FRPD) values up to 39.17 kWm−2 (Figures 14 and 15A) during the nighttime and up to 47.65 kWm−2 (Figures 14 and 15B) for data acquired during daytime

Summary

Introduction

As wildfire events have increased in many areas of the world with catastrophic consequences [1,2,3,4], the ability to accurately monitor these events at different spatial and temporal scales is becoming a key concern and focus for governments around the globe [5,6,7]. Airborne infrared imagery acquired over wildfires is adequate to generate end-products such as fire-front locations [30], rate of spread [24], fire radiative power and fire-line intensity [31]. These estimations can be further compared and/or integrated with satellite imagery, such as Sentinel-3 Sea and Land Surface Temperature Radiometer (SLSTR) [12], the Visible Infrared Imaging Radiometer Suite (VIIRS) [8] and the future Canadian WildFireSat [13], to establish a wildfire management system at local and national scales

Methods

Results

Discussion

Conclusion