Acquisition of Imagery
Digital remote sensing images of forests can be acquired from field-based, airborne, and satellite platforms. Imagery from each platform can provide a data set with which to support forest analysis and modeling, and those data sets may be complementary. For example, field-based remote sensing observations might be comprised of a variety of plot or site photographs or images (Chen et al., 1991) and nonimaging spectroscopy measurements (Miller et al., 1976) which, together with airborne or satellite data, can be used to extend the detailed analysis of a small site to larger and larger study areas. Many types of ground platforms (e.g., handheld, tripod, ladder, mast, tower, tramway or cable car, boom, cherry picker) have been used in remote sensing of forest canopy spectral reflectance (Blackburn and Milton, 1997). The variety of free-flying airborne platforms that have been employed in collecting remote sensing observations is nothing short of astonishing: at various times, airships (Inoue et al., 2000), balloons, paragliders, remotely piloted aircraft, ultralight aircraft, and all manner of fixed-wing light aircraft have all been used with varying degrees of success in remote sensing. While not all of these have operational potential, it is a virtual certainty that in supporting sustainable forest management activities in a forest region, a variety of imagery and data from field-based, airborne, and satellite platforms will be required.