Examples of hyperspectral signatures of different types of tissue and related model fitting
In most cases spectral measurements are done on green leaves or canopies. The green tissue generates a characteristic signature pattern, which varies with the age structure of the plant. In fact, the two dynamic processes "growth" and "senescence" can mask any other factors. A fully grown, mature leaf does not change much, we see some kind of upper asymptote in the signature, again, masking potential traits or factors of interest. But the library also shows the diversity of hyperspectral signatures and gives reasons affecting the signatures. The visual comparison with model fits demonstrate the flexibility of our analysis method for all available spectra, transfering hyperspectral signals into parameters usable for statistics and comparisons.
Classical standard spectrum of a mature green leaf with
all characteristics of a sugar beet leaf. (leaf structure, cuticula, leaf
diameter etc.). Example demonstrates the asymptotic boundary of a
healthy, mature crop. Measurement taken above canopy.
Again, one of the classical results: green, mature
sugar beet leaf, measurement taken with plant probe directly taken from the leaf
surface with own light source and no disturbances in the signal.
Measurements taken with a plant probe were found to result in stable
signals and are most likely to represent some kind of "true" signal of a
tissue. we have constant light conditions and no disturbances in the
reflectance. Data gained on this base allow the statistical analysis
with respect to minor differences in the parameters. We recommend this
method for specific questions in stress responses or trait phenotyping
in greenhouse experiments or simple pot experiments, etc.
Example of an N fertilised vine leaf of
elder age, but before the beginning of senescence.
Vine leaf in the beginning of senescence stage and disturbances in
some domains (760nm). Fitting the model adjusts such disturbances without loss of information. That
is of need, as the usual analysis methods might emphasise on that
domain and would find arbitrary differences.
Green leaf with a thick cuticula and waxed leaf surface,
strong light absorption (= low reflection) in the chlorophyll domains.