数字摄像法测量白天能见度算法设计

数字摄像法测量白天大气能见度,常用的方法是双亮度差法,此方法需尽可能保证标准的观测条件,例如两组目标-背景视线方向一致,尽量选择观测反射率低得可以忽略的人工实用黑体目标物等,否则会产生较大的误差。为此设计了一种新的基于数字摄像机的白天能见度算法:拍摄包含合适的目标物和天空背景图像,通过暗原色先验估计透射率,通过调节光圈大小获得散焦图像,把S变换应用到图像处理中,计算视觉距离,可以得出大气消光系数,从而反演出大气能见度值。实验数据表明,该算法在能见度的值在4 000~8 000 m范围内最大误差小于9%,测量结果比双亮度差方法误差减小2.1%~3.4%。

Design of measuring daytime visibility algorithm of digital photography

The common method for testing daytime visibility by digital photography is dual differential luminance al-gorithm, which asks for standard observation conditions.For example, the two groups of target-background view should be in the same direction and the researcher should try to choose black practical man-made object target to observe, whose reflectivity should be low enough to ignore.Otherwise, serious error will be made.Thus, a new daytime visibility algorithm based on digital camera is proposed , which contains the appropriate object and sky background image.The result of atmospheric visibility could be obtained by estimating transmittance based on dark channel priority and adjusting the camera aperture size to get defocused images, and then the S transform is applied for image processing to computer vision distance to derive atmospheric extinction coefficient values .The experimen-tal data shows that the maximum error of the proposed algorithm is less than 9% in visibility observation range 4 000~8 000 m.This algorithm can make the error of dual differential luminance algorithm reduced by 2.1%~3.4%.