Orthorectification of Helicopter-Borne High Resolution Experimental Burn Observation from Infra Red Handheld Imagers

To pursue the development and validation of coupled fire-atmosphere models, the wildland fire modeling community needs validation data sets with scenarios where fire-induced winds influence fire front behavior, and with high temporal and spatial resolution. Helicopter-borne infrared thermal cameras have the potential to monitor landscape-scale wildland fires at a high resolution during experimental burns. To extract valuable information from those observations, three-step image processing is required: (a) Orthorectification to warp raw images on a fixed coordinate system grid, (b) segmentation to delineate the fire front location out of the orthorectified images, and (c) computation of fire behavior metrics such as the rate of spread from the time-evolving fire front location. This work is dedicated to the first orthorectification step, and presents a series of algorithms that are designed to process handheld helicopter-borne thermal images collected during savannah experimental burns. The novelty in the approach lies on its recursive design, which does not require the presence of fixed ground control points, hence relaxing the constraint on field of view coverage and helping the acquisition of high-frequency observations. For four burns ranging from four to eight hectares, long-wave and mid infra red images were collected at 1 and 3 Hz, respectively, and orthorectified at a high spatial resolution (<1 m) with an absolute accuracy estimated to be lower than 4 m. Subsequent computation of fire radiative power is discussed with comparison to concurrent space-borne measurements.

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A Simple Model for Wildland Fire Vortex–Sink Interactions

Atmosphere ◽

10.3390/atmos12081014 ◽

2021 ◽

Vol 12 (8) ◽

pp. 1014

Author(s):

Bryan Quaife ◽

Kevin Speer

Keyword(s):

Large Scale ◽

Wildland Fire ◽

Fire Behavior ◽

Lateral Spreading ◽

Background Flow ◽

Fire Plume ◽

Poisson Equations ◽

Fuel Burn ◽

Fire Front ◽

The Stability

A model is developed to explore fire–atmosphere interactions due to the convective sink and vorticity sources in a highly simplified and idealized form, in order to examine their effect on spread and the stability of various fire front geometries. The model is constructed in a cellular automata framework, is linear, and represents a background flow, convective sink, and vortices induced by the fire plume at every burning cell. We use standard techniques to solve the resulting Poisson equations with careful attention to the boundary conditions. A modified Bresenham algorithm is developed to represent convection. The three basic flow types—large-scale background flow, sink flow, and vortex circulation—interact in a complex fashion as the geometry of the fire evolves. Fire-generated vortex–sink interactions produce a range of fire behavior, including unsteady spread rate, lateral spreading, and dynamic fingering. In this simplified framework, pulsation is found associated with evolving fire-line width, a fire-front acceleration in junction fires, and the breakup of longer initial fire lines into multiple head fires. Fuel is very simply represented by a single burn time parameter. The model fuel is uniform yet patchiness occurs due to a dynamic interaction of diffusive and convective effects. The interplay of fire-induced wind and the geometry of the fire front depends also on the fuel burn time.

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Automated crop plant counting from very high-resolution aerial imagery

Precision Agriculture ◽

10.1007/s11119-020-09725-3 ◽

2020 ◽

Vol 21 (6) ◽

pp. 1366-1384 ◽

Cited By ~ 1

Author(s):

João Valente ◽

Bilal Sari ◽

Lammert Kooistra ◽

Henk Kramer ◽

Sander Mücher

Keyword(s):

High Resolution ◽

Machine Vision ◽

Surface Area ◽

Spatial Resolution ◽

Image Data ◽

Validation Data ◽

Counting Error ◽

Use Of Resources ◽

Automated Method ◽

Very High

Abstract Knowing before harvesting how many plants have emerged and how they are growing is key in optimizing labour and efficient use of resources. Unmanned aerial vehicles (UAV) are a useful tool for fast and cost efficient data acquisition. However, imagery need to be converted into operational spatial products that can be further used by crop producers to have insight in the spatial distribution of the number of plants in the field. In this research, an automated method for counting plants from very high-resolution UAV imagery is addressed. The proposed method uses machine vision—Excess Green Index and Otsu’s method—and transfer learning using convolutional neural networks to identify and count plants. The integrated methods have been implemented to count 10 weeks old spinach plants in an experimental field with a surface area of 3.2 ha. Validation data of plant counts were available for 1/8 of the surface area. The results showed that the proposed methodology can count plants with an accuracy of 95% for a spatial resolution of 8 mm/pixel in an area up to 172 m2. Moreover, when the spatial resolution decreases with 50%, the maximum additional counting error achieved is 0.7%. Finally, a total amount of 170 000 plants in an area of 3.5 ha with an error of 42.5% was computed. The study shows that it is feasible to count individual plants using UAV-based off-the-shelf products and that via machine vision/learning algorithms it is possible to translate image data in non-expert practical information.

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Estimation of Byram’s Fire Intensity and Rate of Spread from Spaceborne Remote Sensing Data in a Savanna Landscape

Fire ◽

10.3390/fire4040065 ◽

2021 ◽

Vol 4 (4) ◽

pp. 65

Author(s):

Gernot Ruecker ◽

David Leimbach ◽

Joachim Tiemann

Keyword(s):

Remote Sensing ◽

Fuel Consumption ◽

Spatial Resolution ◽

Fire Behavior ◽

Remote Sensing Data ◽

Fire Intensity ◽

Rate Of Spread ◽

Radiative Power ◽

Sentinel 2 ◽

Fire Radiative Power

Fire behavior is well described by a fire’s direction, rate of spread, and its energy release rate. Fire intensity as defined by Byram (1959) is the most commonly used term describing fire behavior in the wildfire community. It is, however, difficult to observe from space. Here, we assess fire spread and fire radiative power using infrared sensors with different spatial, spectral and temporal resolutions. The sensors used offer either high spatial resolution (Sentinel-2) for fire detection, but a low temporal resolution, moderate spatial resolution and daily observations (VIIRS), and high temporal resolution with low spatial resolution and fire radiative power retrievals (Meteosat SEVIRI). We extracted fire fronts from Sentinel-2 (using the shortwave infrared bands) and use the available fire products for S-NPP VIIRS and Meteosat SEVIRI. Rate of spread was analyzed by measuring the displacement of fire fronts between the mid-morning Sentinel-2 overpasses and the early afternoon VIIRS overpasses. We retrieved FRP from 15-min Meteosat SEVIRI observations and estimated total fire radiative energy release over the observed fire fronts. This was then converted to total fuel consumption, and, by making use of Sentinel-2-derived burned area, to fuel consumption per unit area. Using rate of spread and fuel consumption per unit area, Byram’s fire intensity could be derived. We tested this approach on a small number of fires in a frequently burning West African savanna landscape. Comparison to field experiments in the area showed similar numbers between field observations and remote-sensing-derived estimates. To the authors’ knowledge, this is the first direct estimate of Byram’s fire intensity from spaceborne remote sensing data. Shortcomings of the presented approach, foundations of an error budget, and potential further development, also considering upcoming sensor systems, are discussed.

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Experimental validation in Mediterranean shrub fuels of seven wildland fire rate of spread models

International Journal of Wildland Fire ◽

10.1071/wf01006 ◽

2001 ◽

Vol 10 (1) ◽

pp. 15 ◽

Cited By ~ 13

Author(s):

S. Sauvagnargues-Lesage ◽

G. Dusserre ◽

F. Robert ◽

G. Dray ◽

D.W. Pearson

Keyword(s):

Wildland Fire ◽

Fire Risk ◽

Mediterranean Area ◽

Fire Service ◽

Civil Defense ◽

Prescribed Fires ◽

Validation Data ◽

Rate Of Spread ◽

Forest Fire Risk ◽

Validation Experiments

Indexes of forest fire risk are broadcast throughout the Summer months by the French Civil Defense Authority. They are used to guide the deployment of fire prevention resources. However, in some departments, the number of fires during the Winter and Spring months of March–April is equal to or greater than during the Summer months. Some days, conditions are favourable for the propagation of fire (soil moisture content, vegetation in dormancy, relative humidity, ...), but indexes for estimating the risk during this period are not calculated. The objective of this paper is to evaluate various models of fire rate of spread, in order to choose one for Winter and Spring fires. The Fire Service of a department of the French Mediterranean area (the Lozère department) provides the opportunity and the means to conduct validation experiments on prescribed fires. Also, validation data from another department of the French Mediterranean area (Pyrénées Orientales) are presented for the same rate of spread models.

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

Fire ◽

10.3390/fire4040081 ◽

2021 ◽

Vol 4 (4) ◽

pp. 81

Author(s):

Henry Hart ◽

Daniel D. B. Perrakis ◽

Stephen W. Taylor ◽

Christopher Bone ◽

Claudio Bozzini

Keyword(s):

Fire Behavior ◽

Fire Spread ◽

Behavior Prediction ◽

Empirical Relationships ◽

Rate Of Spread ◽

Front Position ◽

Fire Front ◽

Initial Work ◽

The Mean ◽

Behaviour Data

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.

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Fire Weather and Smoke Management

Mountain Meteorology ◽

10.1093/oso/9780195132717.003.0022 ◽

2000 ◽

Author(s):

C. David Whiteman

Keyword(s):

Forest Canopy ◽

Wildland Fire ◽

Fire Suppression ◽

Fire Behavior ◽

Plant Succession ◽

Fire Intensity ◽

Rate Of Spread ◽

Resource Managers ◽

Insect Infestations ◽

Ecological Objectives

Wildland fires consume large areas of forest and grasslands every year. Fires are described in terms of fire behavior, which includes rate of spread and fire intensity. A fire that spreads rapidly burns less of the available fuel per square unit of area than a fire that moves slowly and allows the flaming front a longer residence time. A fire with flames that reach only two feet above the ground produces less heat and is less destructive than an intense fire that crowns, that is, has long flames and burns at the top (i.e., crown) of the forest canopy (figure 13.1). Fire suppression activities are initiated when a wildfire threatens people, property, or natural areas that need protection. These activities include dropping water or chemicals on a fire and establishing a fire line around the fire. A fire line is a zone along a fire’s edge where there is little or no fuel available to the fire. Roads, cliffs, rivers, and lakes can be part of a fire line, or land can be cleared by firefighters. Backfires may be set within the fire line to burn toward the fire, widening the fire line and reducing the likelihood of the fire spreading beyond it (figures 13.2 and 13.3). Fires can cross a fire line if the intensity is high or if spotting occurs, that is, if the wind carries burning material (firebrands) beyond the fire and across the fire line (figure 13.4). A wildland fire can be very destructive, but it can also be beneficial and may be used by land resource managers to accomplish specific ecological objectives. For example, smaller fires can reduce the danger of a large catastrophic fire by burning off underbrush. Fire can also be used to prepare land for planting, to control the spread of disease or insect infestations, to benefit plant species that are dependent on fire, to influence plant succession, or to alter the nutrients in the soil. When a fire is used to manage land resources, it is called a prescribed fire.

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Testing the Effect of Fuel Consumption on Fire Spread Rate

International Journal of Wildland Fire ◽

10.1071/wf9950143 ◽

1995 ◽

Vol 5 (3) ◽

pp. 143 ◽

Cited By ~ 9

Author(s):

RS McAlpine

Keyword(s):

Fuel Consumption ◽

Fire Behavior ◽

Fire Spread ◽

Data Sets ◽

Behavior Prediction ◽

Spread Rate ◽

Data Set ◽

Weak Relationship ◽

Rate Of Spread ◽

Fire Front

It has been theorized that the amount of fuel involved in a fire front can influence the rate of spread of the fire. Three data sets are examined in an attempt to prove this relationship. The first, a Canadian Forest Service database of over 400 experimental, wild, and prescribed fires showed a weak relationship in some fuel complexes. The second, a series of field experimental fires conducted to isolate the relationship, showed a small effect. The final data set, from a series of 47 small plots (3m x 3m) burned with a variety of fuel loadings, also show a weak relationship. While a relationship was shown to exist, it is debatable whether it should be included in a fire behavior prediction system. Inherent errors associated with predicting fuel consumption can be compounded, causing additional, more critical, errors with the derived fire spread rate.

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Resolving vorticity-driven lateral fire spread using the WRF-Fire coupled atmosphere–fire numerical model

Natural Hazards and Earth System Science ◽

10.5194/nhess-14-2359-2014 ◽

2014 ◽

Vol 14 (9) ◽

pp. 2359-2371 ◽

Cited By ~ 17

Author(s):

C. C. Simpson ◽

J. J. Sharples ◽

J. P. Evans

Keyword(s):

High Spatial Resolution ◽

Wildland Fire ◽

Fire Spread ◽

Weather Research And Forecasting ◽

Grid Spacing ◽

Fire Behaviour ◽

Model Framework ◽

Rate Of Spread ◽

Fire Front ◽

Vertical Grid

Abstract. Vorticity-driven lateral fire spread (VLS) is a form of dynamic fire behaviour, during which a wildland fire spreads rapidly across a steep leeward slope in a direction approximately transverse to the background winds. VLS is often accompanied by a downwind extension of the active flaming region and intense pyro-convection. In this study, the WRF-Fire (WRF stands for Weather Research and Forecasting) coupled atmosphere–fire model is used to examine the sensitivity of resolving VLS to both the horizontal and vertical grid spacing, and the fire-to-atmosphere coupling from within the model framework. The atmospheric horizontal and vertical grid spacing are varied between 25 and 90 m, and the fire-to-atmosphere coupling is either enabled or disabled. At high spatial resolutions, the inclusion of fire-to-atmosphere coupling increases the upslope and lateral rate of spread by factors of up to 2.7 and 9.5, respectively. This increase in the upslope and lateral rate of spread diminishes at coarser spatial resolutions, and VLS is not modelled for a horizontal and vertical grid spacing of 90 m. The lateral fire spread is driven by fire whirls formed due to an interaction between the background winds and the vertical circulation generated at the flank of the fire front as part of the pyro-convective updraft. The laterally advancing fire fronts become the dominant contributors to the extreme pyro-convection. The results presented in this study demonstrate that both high spatial resolution and two-way atmosphere–fire coupling are required to model VLS with WRF-Fire.

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Impacts of Forest Thinning on Wildland Fire Behavior

Forests ◽

10.3390/f11090918 ◽

2020 ◽

Vol 11 (9) ◽

pp. 918 ◽

Cited By ~ 3

Author(s):

Tirtha Banerjee

Keyword(s):

Wind Speed ◽

Wildland Fire ◽

Fire Severity ◽

Fire Behavior ◽

Fire Intensity ◽

Fuel Moisture ◽

Forest Thinning ◽

Rate Of Spread ◽

Wide Range ◽

Actual Fire

Key message: We have explored the impacts of forest thinning on wildland fire behavior using a process based model. Simulating different degrees of thinning, we found out that forest thinning should be conducted cautiously as there could be a wide range of outcomes depending upon the post-thinning states of fuel availability, fuel connectivity, fuel moisture and micrometeorological features such as wind speed. Context: There are conflicting reports in the literature regarding the effectiveness of forest thinning. Some studies have found that thinning reduces fire severity, while some studies have found that thinning might lead to enhanced fire severity. Aims: Our goal was to evaluate if both of these outcomes are possible post thinning operations and what are the limiting conditions for post thinning fire behavior. Methods: We used a process based model to simulate different degrees of thinning systematically, under two different conditions, where the canopy fuel moisture was unchanged and when the canopy fuel moisture was also depleted post thinning. Both of these scenarios are reported in the literature. Results: We found out that a low degree of thinning can indeed increase fire intensity, especially if the canopy fuel moisture is low. A high degree of thinning was effective in reducing fire intensity. However, thinning also increased rate of spread under some conditions. Interestingly, both intensity and rate of spread were dependent on the competing effects of increased wind speed, fuel loading and canopy fuel moisture. Conclusion: We were able to find the limits of fire behavior post thinning and actual fire behavior is likely to be somewhere in the middle of the theoretical extremes explored in this work. The actual fire behavior post thinning should depend on the site specific conditions which would determine the outcome of the interplay among the aforementioned conditions. The work also highlights that policymakers should be careful about fine scale canopy architectural attributes and micrometeorological aspects when planning fuel treatment operations.

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Mapping and Monitoring of the Land Use/Cover Changes in the Wider Area of ltanos, Crete, Using Very High Resolution EO Imagery With Specific Interest in Archaeological Sites

10.31219/osf.io/3vrth ◽

2019 ◽

Cited By ~ 1

Author(s):

Sawyer Reid stippa ◽

George Petropoulos ◽

Leonidas Toulios ◽

Prashant K. Srivastava

Keyword(s):

High Resolution ◽

Spatial Resolution ◽

Satellite Images ◽

Archaeological Site ◽

Digital Photography ◽

Archaeological Sites ◽

Large Area ◽

High Resolution Imagery ◽

Site Mapping ◽

Rule Sets

Archaeological site mapping is important for both understanding the history as well as protecting them from excavation during the developmental activities. As archaeological sites generally spread over a large area, use of high spatial resolution remote sensing imagery is becoming increasingly applicable in the world. The main objective of this study was to map the land cover of the Itanos area of Crete and of its changes, with specific focus on the detection of the landscape’s archaeological features. Six satellite images were acquired from the Pleiades and WorldView-2 satellites over a period of 3 years. In addition, digital photography of two known archaeological sites was used for validation. An Object Based Image Analysis (OBIA) classification was subsequently developed using the five acquired satellite images. Two rule-sets were created, one using the standard four bands which both satellites have and another for the two WorldView-2 images their four extra bands included. Validation of the thematic maps produced from the classification scenarios confirmed a difference in accuracy amongst the five images. Comparing the results of a 4-band rule-set versus the 8-band showed a slight increase in classification accuracy using extra bands. The resultant classifications showed a good level of accuracy exceeding 70%. Yet, separating the archaeological sites from the open spaces with little or no vegetation proved challenging. This was mainly due to the high spectral similarity between rocks and the archaeological ruins. The satellite data spatial resolution allowed for the accuracy in defining larger archaeological sites, but still was a difficulty in distinguishing smaller areas of interest. The digital photography data provided a very good 3D representation for the archaeological sites, assisting as well in validating the satellite-derived classification maps. All in all, our study provided further evidence that use of high resolution imagery may allow for archaeological sites to be located, but only where they are of a suitable size archaeological features.

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