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Color Infrared And Vegetation

COLOR INFRARED AND VEGETATION

Natural color digital cameras are sensitive in the spectral regions of Blue (~446 to 520nm), Green (~520 to 600nm) and Red (~630 to 690nm). These individual sensitivities are combined to form images that appear true to the color of the object. Vegetation structure containing the pigments chlorophyll a and b absorb light in the blue and red portions of the spectrum, giving rise to the green color of plant leaves. A human sees the leaf as green due to the photopic response of the eye to the absorption of blue and red.

However, at wavelengths beyond the response of the human eye the cell structure of a healthy plant reflects strongly. The Landsat Thematic Mapper, as shown below as an example, images this Near-Infrared (NIR) spectral region as Band 4 (~760 to 900nm). Differing types of vegetation and differing stresses upon the vegetation will affect the plantís absorption / reflection of Red and NIR radiation.

Nearly 40 years ago Kodak developed a "False Color" film that was sensitive in the NIR portion of the spectrum.This NIR-sensitive layer of the film, when processed to a positive print or transparency, was displayed using a red dye. The red-sensitive film layer was displayed using a green dye and the green-sensitive layer was displayed using a blue dye. The latest (and final) evolution of this False Color Infrared film was the Aerochrome III Infrared Film 1443 and Infrared NP Film SO-734. Kodak has now discontinued manufacture of these film products.

The continuing need for monitoring the global extent and health / vigor of vegetation has resulted in virtually all earth-imaging satellites (i.e. Landsat, SPOT, ASTER, etc.) having the capability to generate Color Infrared imagery using nominal green, red and NIR spectral bands. The Cirrus CIR Camera provides a simple and cost-effective solution to the reduced availability of color-infrared film and the complexity of a multi-camera digital CIR system. Primary applications include delineation of vegetation species and mapping of agriculture health and vigor.

Research & Design

Sample Imagery

CIR Imagery animation

These images highlight the usefulness of Color Infrared Photography for various research programs and governmental projects.