基於逐點計算法之路面平均照度估算方法研究

本文提出一種基於逐點計算法的路面平均照度估算方法，內容包括參考國際間照度取樣方式，以幾何光學原理推導單側、交錯、相對及中央排列路燈之逐點照度計算公式，將之編譯成C程式，進行路面平均照度計算，所得結果再利用商用照明軟體DIALux與傳統係數法進行驗證，以比較國內常見路燈光源、燈具傾斜角與路燈排列方式對路面照度之影響。研究結果顯示，逐點估算法比現行係數法可得更為精確的路面平均照度，路面照度分佈亦較DIALux軟體符合距離平方反比定律，此外，所提逐點估算法對上述四種路燈排列之最佳路面取樣點數作出建議，可供其他方法進行道路照明估算時參考。

關鍵字

路燈照明；平均路面照度；逐點法；最佳取樣點數； DIALux

並列摘要

This paper presents a computational method to estimate the average road-surface illuminance in street lighting. The proposed method is derived based on the one by one dot method which complies with the principle of geometry optics and international convention in sampling road points. The exact road-surface illumination formulas for single-sided, staggered, opposite, and central twin bracket street lightings are derived. A C-language program has been developed for the method to be implemented in computer. Applicability of the formula is confirmed by verification with the commercial lighting software DIALux and the traditional coefficient method. Comparisons in terms of average road-surface illuminance and lighting distribution profile resulted from various light sources, inclination angles of luminaire, and street lighting arrangements are performed. As a result, the one by one dot method generates more accurate results than the coefficient method in calculating average road-surface illiminance. More reasonable lighting distribution profile conforming with the inverse square law of distance is obtained from the one by one dot method instead of DIALux software. In addition, the optimal number of road sampling points in different street lighting arrangements are recommended, which can be referred by other methods for street lighting evaluation.