C. J. Wong C. K. Teo M. Z. MatJafri K. Abdullah H. S. Lim Using webcam for indoor air quality monitoring. 734110 2009 Visual Information Processing http://dx.doi.org/10.1117/12.820329 conf/spieVIP/2009 db/conf/spieVIP/spieVIP2009.html#WongTMAL09