Algorithm for Haze Determination Using Digital Camera Images

摘要

An algorithm for haze determination was developed based on the atmospheric optical properties to determine the concentration of particulate matter with diameter less than 10 micrometers (PM10). The purpose of this study was to use digital camera images to determine the PM10 concentration. This algorithm was developed based on the relationship between the measured PM10 concentration and the reflected components from a surface material and the atmosphere. A digital camera was used to capture images of dark and bright targets at near and far distances from the position of the targets. Ground-based PM10 measurements were carried out at selected locations simultaneously with the digital camera images acquisition using a DustTrak~(TM) meter. The PCI Geomatica version 9.1 digital image processing software was used in all image-processing analyses. The digital colour images were separated into three bands namely red, green and blue for multi-spectral analysis. The digital numbers (DN) for each band corresponding to the ground-truth locations were extracted and converted to radiance and reflectance values. Then the atmospheric reflectance was related to the PM10 using the regression algorithm analysis. The proposed algorithm produced a high correlation coefficient (R) and low root-mean-square error (RMS) between the measured and estimated PM10. This indicates that the technique using the digital camera images can provide a useful tool for air quality studies.