Advances in mapping woody plant canopies using the NASA MISR Instrument on terra

Red (672 nm) band reflectance estimates from the NASA multi-angle imaging spectro-radiometer (MISR) on the earth observing system Terra satellite were used to obtain maps of woody plant fractional crown cover, mean canopy height, and biomass for large parts of south-eastern Arizona and southern New Mexico (>200,000 km²). MISR red band bidirectional reflectance estimates in nine views mapped to a 250 m grid were used to adjust the simple geometric-optical model (SGM) that is based on the principles of Boolean geometry first exploited in Li-Strahler geometric-optical (GO) models. The soil-understory background signal was decoupled a priori by exploiting relationships with the nadir camera reflectance data and the kernel weights of the LiSparse-RossThin kernel-driven bidirectional reflectance distribution function (BRDF) model. Maps of fractional crown cover, mean canopy height, and biomass were produced via retrievals of the mean crown radius and shape parameters from inversion of the SGM using the Praxis algorithm. The mean absolute error in randomly sampled and filtered estimates of fractional crown cover, mean canopy height, and woody biomass was 0.10, 2.2 meters, and 4.5 tons acre^-1 (10.1 Mg ha^-1), with RMS errors of 0.12, 3.3 and 6.2 (14.0), and coefficients of determination (R²) of 0.78, 0.69, and 0.81, respectively, significant at the 0.01 level (N=576).