ASD Document 600540 Rev. J 64 FieldSpec® 3 User Manual
www.asdi.com Chapter 7 Field Measurements
7.8 Rocks, Soils, and Man-Made Materials
The shape of the spectral signature of rocks and soil tends to be invariant with
respect to the viewing geometry, unlike vegetation. The overall brightness of
the observed spectrum does change with illumination and viewing geometry
due to changes in the amount of shadow in the field-of-view of the
spectrometer.
Sensor
• Canopy
» type (plant or tree nominal class)
»closure
» orientation
» systematic (e.g., rows)
» unsystematic (random)
•Crown
» shape (e.g., circular, conical)
» diameter (m)
• Trunk or Stem
» density (units per m
2
)
» tree diameter-at-breast-height: tree trunks or
plant stems have a certain density.
• Leaf
» leaf-area-index: defines the area that interacts
with solar radiation; the surface that is
responsible for carbon absorption and
exchange with the atmosphere.
» leaf-angle-distribution: may change
throughout the day as the leaves orient
themselves toward or away from the incident
radiation.
Understory same as vegetation
Soil
•Texture
•Color
• Moisture content
Table 7-1 Major variables affecting the Bidirectional Reflectance Distribution Function
(BRDF) of a vegetated canopy
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