摘要
开展了烟气条件下疏散指示能见度的初步研究。首先通过实验统计分析了观察者给出的烟气条件下疏散指示能见度等级变化规律,重点分析了疏散指示的亮度对能见度的作用,发现亮度是影响能见度的主要因素。这区别于无烟条件下疏散指示能见度的主要影响因素:亮度、大小和颜色。然后对实验过程中采集到的图像进行分析,获得了疏散指示亮度信息的图像特征——对比度的变化,发现烟气条件下疏散指示图像的对比度变化信息较好地符合了观察者对疏散指示能见度等级评价的变化规律,且在烟气浓度变化缓慢的条件下可以细致评价疏散指示性能,故采用对比度信息来衡量烟气条件下疏散指示的安全性有更大的安全余量。结果表明,数字图像分析是量化烟气条件下疏散指示能见度的一种有效方法。
This paper aims to present our study of visibility of the building exit signs quantitatively and qualitatively through experiments and digital image processing （ DIP）. First of all, we have divided the visibility of the building exit signs into five ranks, marked by ‘ 1 ＇ ,‘2＇,‘3＇,‘4＇,‘5＇, according to the legibility of the signs. Let ‘1＇ stand for ＇ very visible＇ whereas ‘ 5＇ - for ＇ not at all visible＇ . Then observers were randomly invited from USTC campus to rank the signs. When the invited participants in the experiments were asked to observe the exit signs, they are also asked to rate the visibility in smoke conditions. From their response, it can be deduced that luminance is one of the most important factors affecting their choice. This is quite different from that in clean air conditions, where the influential factors may include luminance, color and exit sign size. Secondly, scenes of exit signs in smoke conditions where statistical experiments took place were captured by a color CCD at the speed of 25 frames per second and then processed digitally, i.e. , firstly binary digitalization and then segmentation, to get pixel intensity of the exit sign figure/text as well as its background. Next, we have calculated the contrast value, i.e. , the qualitative features of the luminance in the image of the exit signs in accordance with the pixel intensity. From comparison of the contrast value with the passing time, it can be found that the curves that have elapsed go well with the visibility rank curves given by the observers. Thus, we can believe that such a contrast value can be used not only as an effective means to measure of the visibility of exit signs in smoke conditions, but also as a means to compare the safety of different exit signs quantitatively, especially when the smoke density is combatively low with slow change rate. Therefore, the proposed DIP based method here is expected to evaluate the visibility of exit signs quantitatively and qualitatively.
出处
《安全与环境学报》
CAS
CSCD
2007年第3期110-115,共6页
Journal of Safety and Environment
基金
国家自然科学基金项目(50678164)
国家科技支撑项目(2006BAK06B00)
关键词
安全工程
人员疏散
疏散指示
能见度
图像分析
safety engineering
evacuation
exit signs
visibility
image processing
