Volume 5, No. 1, June 2005, Pages 39-47 PDF(197 KB)
Investigation of Urban Atmospheric Visibility Hsing Haar Wavelet Transform
Chin-Hsiang Luo1, Chung-Shin Yuan2, Che-Yen Wen3, Jiun-Jian Liaw4, Shih-Hsuan Chiu4
1 Department of Environmental Engineering, Hung-Kuang University, 34, Chung-Chie Road, Taichung, Taiwan, R.O.C.
2 Institute of Environmental Engineering, National Sun Yat-Sen University 70, Lien-Hai Road, Kaohsiung, Taiwan, R.O.C
3 Department of Forensic Science, National Central Police University, 56, Shu-Ren Road, Da-Gang, Guei-Shan, Tao-Yuan, Taiwan, R.O.C
4 Department of Polymer Engineering, National Taiwan University of Science and Technology, 43, Kee-lung Road, Section 4, Taipei, Taiwan, R.O.C
A method of image processing, Haar wavelet transform, was first applied to establish a new index and provide accurate digital data to present urban atmospheric visibility, instead of the conventional observing method. Digital images of urban areas in Kaohsiung, a city at the south of Taiwan, are analyzed according to brightness (gray level). An index value for a scene image is calculated with a processor of Haar wavelet transform. As a result, a good correlation between the wavelet index values and the visual range values estimated by three trained observers is affirmed by the correlation coefficient (R2) of 0.81. Convenient transmission and the exchangeability of digital images of the real-time landscape facilitate the demonstration of the results on the web site.
Visibility; Wavelet transform; Image processing; Air quality.