作者：徐博林、杜媛媛、陳神飛、楊松柏、李緯晟、張兵、李田茵、趙海天(深圳大學(xué)建筑與城市規(guī)劃學(xué)院)
我們基于低位道路照明研究了一種新的方法來(lái)增強(qiáng)霧的能見(jiàn)度。
實(shí)驗(yàn)裝置：如圖所示，該實(shí)驗(yàn)是在長(zhǎng)度為1.5米*寬度為1.2米*高度為4.0米的密封裝置中進(jìn)行的，根據(jù)準(zhǔn)確比例1:15模擬了一條長(zhǎng)度為60米，三車(chē)道寬度為3.75米，緊急車(chē)道寬度為3.0米的高速公路。
我們使用亮度成像儀記錄目標(biāo)的亮度，汽車(chē)照明由兩個(gè)LED聚光燈模擬。照度計(jì)收集聚光燈的照度值。低位路燈設(shè)置在兩側(cè)40厘米的距離內(nèi)，以模擬路燈。目標(biāo)1距離亮度成像儀1.5米，目標(biāo)2距離亮度成像儀3.0米。聚光燈和照度計(jì)用于計(jì)算霧濃度。實(shí)驗(yàn)裝置的所有控制電源均通過(guò)無(wú)線控制終端進(jìn)行集中遠(yuǎn)程控制。
實(shí)驗(yàn)過(guò)程：
在無(wú)霧情況下，即相對(duì)霧濃度為0時(shí)，采用機(jī)動(dòng)車(chē)照明和低位照明時(shí)的兩種照明環(huán)境下，機(jī)動(dòng)車(chē)照明環(huán)境優(yōu)于低位照明環(huán)境。然后，我們向裝置內(nèi)加霧。在此過(guò)程中，切換兩種照明形式，我們很容易發(fā)現(xiàn)使用汽車(chē)照明會(huì)引起強(qiáng)烈的白墻效果。
當(dāng)霧濃度為1時(shí)，霧濃度最高，使用汽車(chē)照明會(huì)產(chǎn)生嚴(yán)重的“白墻現(xiàn)象”，在兩種照明條件下都無(wú)法確定目標(biāo)。
最后，停止加霧，隨著霧濃度降低，低位道路照明先于汽車(chē)照明確定目標(biāo)1。
霧濃度為0.957時(shí)，隨著霧濃度的降低，在汽車(chē)照明中只能觀察到目標(biāo)1，而在低位置道路照明中能觀察到目標(biāo)2，并且在低位道路照明中可以觀察到目標(biāo)2的亮度對(duì)比度比汽車(chē)照明中的目標(biāo)1高。這也表明，與汽車(chē)照明相比，采用低位道路照明可以將可見(jiàn)度從1.5米提高到3.0米。
霧氣濃度為0.594時(shí)，隨著霧氣濃度一定程度的降低，白墻現(xiàn)象消失，汽車(chē)照明中目標(biāo)1的識(shí)別效果優(yōu)于低位道路照明。對(duì)于近距離目標(biāo)1，汽車(chē)照明的亮度對(duì)比度值高于低位道路照明的亮度對(duì)比度值。但是對(duì)于較遠(yuǎn)的目標(biāo)2，低位道路照明比汽車(chē)照明要好。
實(shí)驗(yàn)結(jié)論：在濃霧天氣下，低位道路照明比汽車(chē)照明將裸眼能見(jiàn)度增加一倍以上。
AMethod to Enhance Visibility in Fog
We develop a new method toenhance visibility in fog based on low-position road lighting.
Asis shown in the picture The experiment is conducted in a hermetic equipmentthat is 1.5 meters in length*1.2 meters in width*4.0 meters in height,simulating the highway which is 60 meters in length, 3.75 meters in width by 3lanes and 3.0 meters in width by an emergency lane according to the accurateratio of 1:15.
We use luminance imager to recordthe luminance of the targets, Automotive lighting is simulated by two LEDspotlights. The illuminometer collects the illuminance value of the spotlight.The low-position road lights are set in the distance of 40 centimeters on bothsides for simulating road lighting. Target 1 is 1.5 meters away from luminanceimager and Target 2 is 3.0 meters away from luminance imager. Spotlight andilluminometer is used to calculate the fog concentration. All control powersupplies of the experimental device adopted centralized remote control by awireless Control Terminal.
1、Next, start the experiment. Whenthere is no fog, that is to say, the relative fog concentration is 0, theenvironment under automotive lighting is better than that under low-positionlighting when adopting the two illuminating forms.
Then, we fill the device withfog. In this process, switching the two illuminating forms, we easily find thatusing automotive lighting will cause a strong white wall effect.
2、When the fog concentration is 1,the fog concentration is the highest, and using automotive lighting wouldproduce a serious "white wall phenomenon", targetsin both lighting conditions can’t be identified.
3、Finally, stop generating fog, asfog concentration decreases, target 1 is identified in low-position roadlighting preceding automotive lighting.
4、Whenthe fog concentration is 0.957, as fog concentrationdecreases, only the target 1 can be observed in automotive lighting while thetarget 2 can be observed in low-position road lighting, and the luminancecontrast of target 2 in low-position road lighting is higher than that oftarget 1 in automotive lighting. This also indicates that, compared withautomotive lighting, the visibility can be increased from 1.5 meters to 3.0meters by adopting low-position road lighting.
5、When the fog concentration is0.594, as fog concentration decreases by a certain extent, the white wallphenomenon disappears and the identification of target 1 in automotive lightingis better than that of low-position road lighting.For close-range target 1, the luminance contrast value of automotive lightingis higher than that of low-positionroad lighting. But for distant target 2, that low-position roadlighting is better than automotive lighting.
