Comprehensive methodology for tracking burning firebrands in a vertical wind tunnel using multi-view video analysis

Misarah Abdelaziz; Andrew. L. Sullivan

doi:10.1071/WF25153

RESEARCH ARTICLE (Open Access)

Next Contents Vol 34(10)

Comprehensive methodology for tracking burning firebrands in a vertical wind tunnel using multi-view video analysis

Misarah Abdelaziz

^A ^* and Andrew. L. Sullivan

^A

+ Author Affiliations

- Author Affiliations

^A CSIRO, GPO Box 1700, Acton, Canberra, ACT 2601, Australia.

^* Correspondence to: E misarah.abdelaziz@csiro.au

International Journal of Wildland Fire 34, WF25153 https://doi.org/10.1071/WF25153

Submitted: 17 June 2025 Accepted: 22 September 2025 Published: 17 October 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of IAWF. This is an open access article distributed under the Creative Commons Attribution 4.0 International License (CC BY).

Abstract

Background

Burning debris (firebrands) can potentially travel significant distances to ignite spot fires many kilometres downwind of a wildfire, posing substantial challenges for fire spread prediction and management.

Aim

To improve our understanding of the combustion and flight behaviours of common bark firebrands through better quantification and detailed analysis of their motion, combustion and aerodynamic behaviour.

Methods

A custom firebrand tracking system consisting of three synchronised video cameras positioned orthogonally around the working section of a vertical wind tunnel was built and bespoke image processing algorithms developed to automatically reconstruct the 3D trajectory and combustion behaviour of a bark sample.

Key results

The system was found to accurately estimate bark sample position as well as spatial velocity, orientation changes and burnout profile.

Conclusions

A robust and accurate methodology to track the dynamic trajectory and behaviour of untethered burning bark falling at its terminal velocity was developed that overcomes many of the limitations of previous tracking approaches.

Implications

This study, applicable to a broad range of bark species as well as other firebrand materials under varying conditions, enables the development of more accurate predictive models of firebrand transport that will help improve the simulation and prediction of spotting in wildfires.

Keywords: 3D trajectory, bushfire behaviour, combustion dynamics, computer vision, fluid mechanics experiment, image processing algorithm, inconsistent particle tracking, spotfire, spotting.

References

Abdelaziz M, Sullivan A (2024) The modification and characterisation of the CSIRO vertical wind tunnel for the study of untethered freefalling firebrands. In ‘Proceedings of the 24th Australasian Fluid Mechanics Conference (AFMC)’. Canberra, Australia. Paper No. AFMC2024-299. doi:10.5281/zenodo.14213598

Almeida M, Porto L, Viegas D (2021) Characterization of firebrands released from different burning tree species. Frontiers in Mechanical Engineering 7, 651135.
| Crossref | Google Scholar |

Bathija A, Sharma G (2019) Visual object detection and tracking using YOLO and SORT. International Journal of Engineering Research Technology 8(11), 345-355.
| Google Scholar |

Bouvet N, Link ED, Fink SA (2021) A new approach to characterize firebrand showers using advanced 3D imaging techniques. Experiments in Fluids 62(9), 181.
| Crossref | Google Scholar |

Carranza F, Zhang Y (2017) Study of drag and orientation of regular particles using stereo vision, Schlieren photography and digital image processing. Powder Technology 311, 185-199.
| Crossref | Google Scholar |

Cruz M, Sullivan A, Gould J, Sims N, Bannister A, Hollis J, Hurley R (2012) Anatomy of a catastrophic wildfire: the Black Saturday Kilmore East fire in Victoria, Australia. Forest Ecology and Management 284, 269-285.
| Crossref | Google Scholar |

Cruz MG, Gould JS, Alexander ME, Sullivan AL, McCaw WL, Matthews S (2015) Empirical-based models for predicting head-fire rate of spread in Australian fuel types. Australian Forestry 78(3), 118-158.
| Crossref | Google Scholar |

Diwan T, Anirudh G, Tembhurne JV (2023) Object detection using YOLO: challenges, architectural successors, datasets and applications. Multimedia Tools and Applications 82(6), 9243-9275.
| Crossref | Google Scholar |

Ellis P (2010) The effect of the aerodynamic behaviour of flakes of jarrah and karri bark on their potential as firebrands,. Journal of the Royal Society of Western Australia 93, 21-27.
| Google Scholar |

Ellis P (2011) Fuelbed ignition potential and bark morphology explain the notoriety of the eucalypt messmate ‘stringybark’ for intense spotting. International Journal of Wildland Fire 20(7), 897-907.
| Crossref | Google Scholar |

Ellis P (2013) Firebrand characteristics of the stringy bark of messmate (Eucalyptus obliqua) investigated using non-tethered samples. International Journal of Wildland Fire 22(5), 642-651.
| Crossref | Google Scholar |

Ellis P (2015) The likelihood of ignition of dry-eucalypt forest litter by firebrands. International Journal of Wildland Fire 24(2), 225-235.
| Crossref | Google Scholar |

Ellis PF (2000) The aerodynamic and combustion characteristics of eucalypt bark: a firebrand study. PhD Thesis, Department of Forestry, The Australian National University, Canberra, ACT, Australia. doi:10.25911/5D7A2814C478D

Filkov A, Prohanov S (2019) Particle tracking and detection software for firebrands characterization in wildland fires. Fire Technology 55, 817-836.
| Crossref | Google Scholar |

Filkov AI, Tihay-Felicelli V, Masoudvaziri N, Rush D, Valencia A, Wang Y, Blunck DL, Valero MM, Kempna K, Smolka J, et al. (2023) A review of thermal exposure and fire spread mechanisms in large outdoor fires and the built environment. Fire Safety Journal 140, 103871.
| Crossref | Google Scholar |

Hall J, Ellis PF, Cary GJ, Bishop G, Sullivan AL (2015) Long-distance spotting potential of bark strips of a ribbon gum (Eucalyptus viminalis). International Journal of Wildland Fire 24(8), 1109-1117.
| Crossref | Google Scholar |

Hines F, Hines F, Tolhurst KG, Wilson AA, McCarthy GJ (2010) Overall Fuel Hazard Assessment Guide. Fire and Adaptive Management Report No. 82. (Victorian Government Department of Sustainability: Melbourne, Vic, Australia)

Knight I (2001) The design and construction of a vertical wind tunnel for the study of untethered firebrands in flight. Fire Technology 37(1), 87-100.
| Crossref | Google Scholar |

Knight I, Ellis P, Sullivan A (2001) The CSIRO Vertical Wind Tunnel. (CSIRO Forestry and Forest Products: Canberra, ACT, Australia)

Koo E, Pagni PJ, Weise DR, Woycheese JP (2010) Firebrands and spotting ignition in large-scale fires. International Journal of Wildland Fire 19(7), 818-843.
| Crossref | Google Scholar |

MATLAB (2023) Version 23.2.0 (R2023b). (The MathWorks Inc.: Natick, MA, USA)

McArthur AG (1967) ‘Fire behaviour in eucalypt forests.’ Forestry and Timber Bureau Leafet 107. (Commonwealth Department of National Development: Canberra, ACT, Australia)

McArthur AG (1969) The Tasmanian bushfires of 7th February, 1967, and associated fire behaviour characteristics. In ‘Mass Fire Symposium’, 10–12 February 1969, Collected Papers. 24 p. (Defence Standards Laboratory: Maribyrnong, Vic, Australia)

Petersen AJ, Banerjee T (2024) Characterizing firebrands and their kinematics during lofting. Physics of Fluids 36(10), 106611.
| Crossref | Google Scholar |

Prevost CG, Desbiens A, Gagnon E (2007) Extended Kalman filter for state estimation and trajectory prediction of a moving object detected by an unmanned aerial vehicle. In ‘2007 American Control Conference’. pp. 1805–1810. (IEEE: New York, NY, USA)

Sullivan A, Ball R (2012) Thermal decomposition and cobustion chemistry of cellulosic biomass. Atmospheric Environment 47, 133-141.
| Crossref | Google Scholar |

Sullivan AL (2017) Inside the inferno: fundamental processes of wildland fire behaviour. Part 2: Heat transfer and interactions. Current Forestry Reports 3, 150-171.
| Crossref | Google Scholar |

Sullivan AL, McCaw WL, Cruz MG, Matthews S, Ellis PF (2012) Fuel, fire weather and fire behaviour in Australian ecosystems. In ‘Flammable Australia: Fire Regimes, Biodiversity and Ecosystems in a Changing World’. (Eds RA Bradstock, AM Gill, RD Williams) pp. 51–77. (CSIRO Publishing: Melbourne, Vic, Australia)

Tohidi A, Kaye NB (2017) Aerodynamic characterization of rod-like debris with application to firebrand transport. Journal of Wind Engineering and Industrial Aerodynamics 168, 297-311.
| Crossref | Google Scholar |

Tolhurst KG, Cheney NP (1999) Synopsis of the knowledge used in prescribed burning in Victoria. (Department of Natural Resources, Environment)

Wadhwani R, Sullivan C, Wickramasinghe A, Kyng M, Khan N, Moinuddin K (2022) A review of firebrand studies on generation and transport. Fire Safety Journal 134, 103674.
| Crossref | Google Scholar |

Zhejiang Uniview Technologies Co., Ltd. (2021) EZStation [computer software]. Available at https://www.uniview.com.