Thierry Molinier

A 3D vision system for the measurement of the rate of spread and the height of fire fronts

This paper presents a three-dimensional (3D) vision-based instrumentation system for the measurement of the rate of spread and height of complex fire fronts. The proposed 3D imaging system is simple, does not require calibration, is easily deployable in indoor and outdoor environments and can handle complex fire fronts. New approaches for measuring the position, the rate of spread and the height of a fire front during its propagation are introduced. Experiments were conducted in indoor and outdoor conditions with fires of different scales. Linear and curvilinear fire front spreading were studied. The obtained results are promising and show the interesting performance of the proposed system in operational and complex fire scenarios.

Estimation of fire volume by stereovision

This paper presents a new approach for the estimation of fire front volume in indoor laboratory experiments. This work deals with fire spreading on inclinable tables. The method is based on the use of two synchronized stereovision systems positioned respectively in a back position and in a front position of the fire propagation direction. The two vision systems are used in order to extract complementary 3D fire points. The obtained data are projected in a same reference frame and used to build a global form of the fire front. An inter-systems calibration procedure is presented and permits the computation of the projection matrix in order to project all the data to a unique reference frame. From the obtained 3D fire points, a three dimensional surface rendering is performed and the fire volume is estimated.

Measurement of the geometric characteristics of a fire front by stereovision techniques on field experiments

This paper presents stereovision techniques for measurement of the geometrical properties (position, rate of spread, fire height, fire inclination angle, fire base width, view factor) of fires obtained by experimental burnings at field scale. The system consists of two synchronized and pre-calibrated multi-baseline stereo cameras operating in the visible spectrum. The cameras are positioned in the back and the lateral positions relatively to the direction of fire propagation. Algorithms have been developed in order to (i) register these cameras, (ii) model in three dimensions the fire front from the back stereoscopic images and (iii) estimate some geometrical properties of fire such as the inclination angle and the fire base width from the lateral stereoscopic images. A user graphical interface was developed as a practical tool to estimate fire propagation features and to display the obtained results. Fire spread experiments were conducted at field scale (about 20 m wide and 3 m high). The fuel consists of Mediterranean shrub vegetation. The obtained results are promising and show interesting performance achieved by the proposed system in operational and complex fire scenarios.

Relationship Between Flame Length and Fireline Intensity Obtained by Calorimetry at Laboratory Scale

The difficulties in measuring Byrams fireline intensity have led many researchers to derive an empirical relation between the fireline intensity and flame length, which is easier to measure at the practical (firefighting) level. In this article, we address both the estimation of Byrams fireline intensity by comparison with oxygen consumption calorimetry (OC) measurement and the test of formulations for fireline intensity versus flame length. We directly measured the fireline intensity for spreading fires on a laboratory scale under conditions of no wind and no slope by OC. The fires were set across beds of Pinus pinaster needles, Avena fatua straw, and Genista salzmannii spines. Fireline intensity obtained by OC ranged from 28 to 160 kW/m, depending on species and load. Byrams index of fire intensity ranged from 38 to 185 kW/m. It was observed that Byrams intensity overestimated the fireline intensity measured by OC. Combustion efficiency was introduced in Byrams formulation, which led to a better estimate of fireline intensity. The indirect estimation of fireline intensity through the observation of the flame length was carried out using a stereovision system. Mean flame length ranged from 0.35 to 0.84 m according to the species and the fuel load. A new relationship was established between the fireline intensity and the flame length.

Measurement of laboratory fire spread experiments by stereovision

This paper presents a stereovision framework developed to monitor and to measure laboratory fire spreads. New algorithms were developed for the estimation of fire characteristics like position, rate of spread, height, depth and the distance between the fire front and metrological instruments.

Image processing and vision for the study and the modeling of spreading fires

This paper presents a work conducted in the field of image processing and computer vision in order to measure geometrical characteristics of spreading fires; this allows understanding the phenomenon occurring during the propagation and improving and/or validating mathematical models by comparing experimental data with numerical ones. In order to develop a metrological system based on vision for wildland fires, it is necessary to solve scientific locks that are also presented in this paper.

Stereovision for the determination of fireline intensity in vegetation fire

Fireline intensity is one of the most relevant quantities in forest fire science. It helps to evaluate the effects of fuel treatment on fire behaviour, to establish limits for prescribed burning. It is also used as a quantitative basis to support fire suppression activities. However, its measurement at field scale for actual fire remains a challenge. Hence, it has been poorly used as a key quantity to test the new generation of models of fire spread that have been developed these last ten years. An inverse method to obtain fireline intensity is through the observation of the flame length. This geometrical information is measured using a stereovision system placed in the lateral position relative to the direction of the fire spread. Algorithms were developed in order to automatically segment the fire area of the images and estimate the 3D coordinates of salient fire points and then the flame length. The three dimensions of the information permit to obtain the flame length with metric measures. In the present work, we directly measure the fireline intensity at laboratory scale by oxygen consumption calorimetry. The results are then used to establish a relationship between fireline intensity and flame length obtained by the stereovision system

Stereovision based algorithm for measuring fire spreading characteristics

This paper presents a new algorithm for automatically measuring fire spreading characteristics by means of a stereovision system. The proposed framework is based on the use of a pre-calibrated trinocular stereo camera. The first and second steps permit the segmentation and features detection in the images. The third step is a stereo matching approach used in order to automatically process successive images of spreading fires. In the fourth step, stereovision techniques are applied in order to derive the 3D fire structure. In the last step, new developed algorithms are used to estimate, in the case of complex fire spreading, information like the position of the fire over time, its rate of spread and its height.