Vegetation canopy reflectance drivers: which parameters are considered when determining canopy reflectance in optical remote sensing?

Introduction / Context:
Canopy reflectance depends not only on leaf properties but also on illumination and viewing geometry and the canopy architecture. These controls are formalized in bidirectional reflectance distribution function (BRDF) models used to normalize and interpret satellite data.

Given Data / Assumptions:

• Solar zenith and azimuth define illumination geometry.
• Sensor look angle defines viewing geometry.
• Leaf number, orientation, and clumping define canopy structure.

Concept / Approach:
Changing sun–sensor geometry alters path lengths and shadow fractions, producing anisotropic reflectance (hotspot effects, forward/backscatter asymmetry). Canopy architecture modulates multiple scattering and shadowing, thus affecting reflectance magnitude and shape across wavelengths.

Step-by-Step Solution:
Include solar zenith/azimuth: control illumination and cast shadows.Include look angle: controls sensor-viewed mixture of lit and shaded elements.Include leaf arrangement: dictates gap fraction and multiple scattering.Therefore, all listed parameters are considered.

Verification / Alternative check:
BRDF corrections and canopy radiative transfer models (e.g., SAIL, PROSAIL) explicitly include these parameters.

Why Other Options Are Wrong:

• Any subset omits important drivers of anisotropy and reflectance magnitude.

Common Pitfalls:

• Ignoring geometry when comparing multi-temporal imagery, leading to false change detection.

Final Answer:
All of these