Leaf directional-hemispherical or bidirectional reflectance and transmittance spectra can directly feed canopy reflectance models as input parameters, but the measurement of these properties is not an end in itself. A large number of spectral analysis methods have been proposed to detect plant biochemistry, ranging from simple band ratios to inversion of radiative transfer methods of varying complexity. The estimation of leaf biophysical parameters is often developed in parallel with the estimation of canopy characteristics, using the same methods as detailed below.