Estimating canopy spectral invariants from ground reference and remote sensing data

Physically-based remote sensing methods have progressively become more attractive for monitoring the vertical and horizontal structure of vegetation. A relatively recent development in modeling the radiation field of a vegetation canopy is the spectral invariants theory. The theory states that the radiation budget of a vegetation canopy can be parameterized using only spectrally invariant parameters which depend on canopy structure in a complex manner. In this paper, we briefly review how spectral invariants can be estimated from hyperspectral remote sensing data or in situ vegetation canopy gap fraction measurements.