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Aerial Films for Forest Inventory: 0ptimizing Film Parameters

1995; American Society for Photogrammetry and Remote Sensing; Volume: 61; Issue: 3 Linguagem: Inglês

2374-8079

Livio Fent, Ronald J. Hall, R. K. Nesby,

Species Distribution and Climate Change

Recent advances in aerial film emulsions and processing techniques have not been evaluated to determine their suitability to forest inventory operations. Five black-and-white films (Kodak's Double-X 2405, Infrared 2424, and Panatomic-X 2412; Agfa's Aviphot Pan 200; and Ilford's FP3) and two color films (Kodak's Aerocolor 2445, and Aerochrome Infrared 2443 processed as a positive and as a negative) were evaluated for their accuracy and user preference for forestry photo interpretation at a scale of 1:20,000. The black-and-white films were also exposed and processed at three average gradients (1.0, 1.4, 1.8) except for the Panatomic-X (1.8, 2.0, 2.2) and Ilford FP3 (1.4 only). Species composition, crown closure, stems per hectare, and height were examined collectively to determine photointerpretation accuracy for each film/average gradient combination. The highest interpretation accuracies were attained when average gradients produced densitometric range measurements of 0.11 to 0.17 (0.12-mm aperture) in mixed coniferous-deciduous forest stands. The Panatomic-X emulsion achieved the highest interpretation accuracy (83 percent) and Aerocolor 2445 attained the lowest (68 percent). Interpreter preference was highest with Aerochrome I.R. 2443 positive processing (7.2 on a scale of 1 to 10) and lowest with Aerochrome I.R. 2443 negative processing (4.1 on a scale of 1 to 10). Higher interpreter preferences were associated with increasing spectral sensitivity to the infrared. There was no correlation, however, between interpreter accuracy and preference for the 16 average gradient/film combinations. Using Panatomic-X film in forest inventory entails practical trade-offs between gains in interpretation accuracy and its requirements for proper exposure. Panatomic-X is a fine-grained, slow speed film with narrower exposure latitude, narrower photo acquisition windows (day and season) relative to other panchromatic films, and likely requires image motion compensation for optimal exposure at a scale of 1:20,000