Georeferencing Oblique Aerial Wildfire Photographs: An Untapped Source of Fire Behaviour Data

Henry Hart,Daniel D B Perrakis,Stephen W Taylor,Christopher Bone,Claudio Bozzini

doi:10.3390/fire4040081

Henry Hart, Daniel D B Perrakis + Show 3 more

Open Access

https://doi.org/10.3390/fire4040081

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Abstract

In this study, we investigate a novel application of the photogrammetric monoplotting technique for assessing wildfires. We demonstrate the use of the software program WSL Monoplotting Tool (MPT) to georeference operational oblique aerial wildfire photographs taken during airtanker response in the early stages of fire growth. We located the position of the fire front in georeferenced pairs of photos from five fires taken 31–118 min apart, and calculated the head fire spread distance and head fire rate of spread (HROS). Our example photos were taken 0.7 to 4.7 km from fire fronts, with camera angles of incidence from −19° to −50° to image centre. Using high quality images with detailed landscape features, it is possible to identify fire front positions with high precision; in our example data, the mean 3D error was 0.533 m and the maximum 3D error for individual fire runs was less than 3 m. This resulted in a maximum HROS error due to monoplotting of only ~0.5%. We then compared HROS estimates with predictions from the Canadian Fire Behavior Prediction System, with differences mainly attributed to model error or uncertainty in weather and fuel inputs. This method can be used to obtain observations to validate fire spread models or create new empirical relationships where databases of such wildfire photos exist. Our initial work suggests that monophotogrammetry can provide reproducible estimates of fire front position, spread distance and rate of spread with high accuracy, and could potentially be used to characterize other fire features such as flame and smoke plume dimensions and spotting.

Highlights

Fire behaviour prediction is important to operational wildfire decision-making and fire fighter safety [1]
There is a paucity of reliable wildfire spread observations to evaluate the Fire Behaviour Prediction (FBP) System head fire rate of spread (HROS) models, or all types of fire spread and growth models [15,16,17]
We demonstrate a method to extract wildfire spread observations from oblique aerial photographs taken during wildfire response in the province of British Columbia, Canada

Summary

Introduction

Fire behaviour prediction is important to operational wildfire decision-making and fire fighter safety [1]. 2. Demonstrate the use of the procedure to obtain estimates of wildfire spread rates and validate fire behaviour models, using the FBP System models as an example. Demonstrate the use of the procedure to obtain estimates of wildfire spread rates and validate fire behaviour models, using the FBP System models as an example To address these objectives, we investigated a novel application of a conventional photogrammetric method called monoplotting to extract fire behaviour data from oblique aerial images. While our immediate goal was to investigate the utility and limitations of this method to obtain observations to validate HROS models within the Canadian FBP System, the method can be used to georeference oblique wildfire photographs for other fire behaviour or management applications

Monoplotting Process

Resu44lABts

Findings

Recommendations for Future Research and Application