A computer-graphics based model for radiation interception in vegetation canopies is used to investigate the feasibility of estimating leaf size and crown size, for deciduous and coniferous trees, from canopy reflectance in the hotspot region. For deciduous trees, as represented by aspen trees, it appears that under certain conditions one can estimate leaf size; we specify optimal Sun-view geometry, wavelength, and index, which can minimize the impacts of other structural parameters (e.g., leaf area index, leaf angle distribution, and interplant spacing) for the most accurate estimation of leaf size. However, for coniferous trees an accurate estimation of crown size seems unlikely, except possibly for sparsely spaced canopies. ¿ 1997 American Geophysical Union