Computer-Assisted Photointerpretation Aids to Forest Inventory Mapping: Some Possible Approaches

Aerial photointerpretation is the mainstay of management forest inventories. Accuracy and consistency of this interpretation is a major concern. In addition there is a growing demand for these inventories to provide more quantitative information and data on new forest parameters. Incorporation of computer-assisted techniques to the interpretation process offers potential to improve forest inventories along these fronts.Techniques must fit into the current infrastructure of mainly small or independent interpreter groups or individuals using 1:10 000 to 1:20 000 scale stereo photography. Computer-assisted interpretation therefore must be based on digitized photography and not necessitate large computers or costly display systems or analysis software. They must be simple to apply and not require inordinate fine tuning or trial and error by the interpreter.Envisaged techniques are: 1) computer-based interpretation keys, 2) recall acid display of ancillary data, 3) computer-assisted interpretation review where interpreters can quickly compare all stands they have interpreted as a given stand type, 4) automated single tree analysis including automated single tree isolation, delineation and species classification, plus estimations of stems/ha, crown closure, crown size, numbers of snags, and gap or patch size distribution, and 5) pixel and area based features such as conventional pixel classification and various texture measures for stands that could be presented visually or numerically to the interpreter as an aid. As well, visual or parametric comparison of current and past inventory photography presents a vast array of possible benefits to interpretation.