In case of fire, the visibility plays a major role as it limits the occupants’ orientation capabilities and the perception of signs. These effects are determined by the light extinction due to smoke or other aerosols produced in fires. The presented method is based on the optical observation of an array of light sources during a fire in a laboratory experiment. The smoke induced into the compartment leads to a drop in intensity of each individual light source. This information is used to deduce the extinction along the line-of-sight to the camera. Once the data are captured, an automated processing is used to locate the diodes on the images and determine their intensity. Here, the optical image of the small diodes is assumed to have a known shape, so that the optimisation algorithm is capable to identify the location of the diode's centre and quantify the luminosity in a sub-pixel range. The result is a time series for each diode, indicating the change of the relative luminosity, w.r.t. the initial values. Finally, a model for the extinction along each line-of-sight is formulated. It assumes that the light extinction coefficient is distributed in homogeneous layers. The number of layers is a free model parameter. Given this spatial distribution of the extinction coefficient and the experimental geometry, each line-of-sight is impacted by a number of layers, of yet unknown coefficient values. An inverse modelling approach is used here to find coefficient values that match the modelled line-of-sight extinction with the observed luminosity drops. The final result is a time- and height-dependent distribution of the light extinction coefficient during the full experiment.

中文翻译：

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隔间火灾消光系数的时空测量

在发生火灾时，能见度起着重要作用，因为它限制了居住者的定向能力和对标志的感知。这些影响是由火灾中产生的烟雾或其他气溶胶引起的光熄灭决定的。所提出的方法基于在实验室实验中火灾期间对光源阵列的光学观察。进入隔间的烟雾会导致每个单独光源的强度下降。该信息用于推断沿视线到相机的消光。捕获数据后，将使用自动处理来定位图像上的二极管并确定它们的强度。这里，假设小二极管的光学图像具有已知形状，因此优化算法能够识别二极管的位置' s 中心并量化子像素范围内的亮度。结果是每个二极管的时间序列，指示相对光度的变化，与初始值对应。最后，制定了沿每个视线的灭绝模型。它假设消光系数分布在均匀层中。层数是一个自由模型参数。鉴于消光系数的这种空间分布和实验几何，每个视线都受到许多层的影响，这些层的系数值未知。此处使用逆建模方法来查找将建模的视线消光与观察到的光度下降相匹配的系数值。最终结果是整个实验过程中消光系数的时间和高度相关分布。