Remotely sensed estimation of forest canopy density: a comparison of the performance of four methods, Chudamani Joshi,; Leeuw, J, de; Skidmore, A, K.; Duren, I, C. van; Oosten, H, van , International Journal of Applied Earth Observation and Geoinformation, Volume 8, Number 2, p.84-95, (2006) Abstract