Evaluation of Infrared-Sensitive Film for Determination of Spectral Quality within a Forest Canopy

Abstract

Kodak Ektachrome Infrared film was evaluated in terms of its potential use for qualitative spectral information on solar radiation within plant canopies. It was found that an exposure rating of 125 (ASA) provides properly exposed images using through-the-lens metering, with infrared images of forest species in shaded areas appearing deep red (as these species reflect strongly in the infrared), while images of sunfleck illuminated species appear yellow because they reflect in the green spectral region. Infrared color film serves as an inexpensive means of supplementing spectroradiomctric analysis of light within canopy systems, and provides semi-qualitative information about the source of radiation of a particular wave-length. The major limitation observed was the film's tendency to form numerous colors which, in effect, masked the primary colors.