Organism Silhouette Area using Shape Approximations

The function estimates the projected (silhouette) area as a portion of the surface area of the organism. The function estimates the projected area as a function of the dimensions and the angle between the solar beam and the longitudinal axis of the solid, using Figure 11.6 in Campbell and Norman (1998) . The function is useful for estimating absorbed solar radiation.

proportion_silhouette_area_shapes(shape, theta, h, d)

Arguments

shape

character Shape to use to approximate an organism. Shapes are assumed to be prolate or have the longest axis parallel with the ground. Current choices are "spheroid", "cylinder flat ends", and "cylinder hemisphere ends".

theta

numeric angle between the solar beam and the longitudinal axis (degrees).

h

numeric height (long axis in m). Cross section length for spheroid.

d

numeric diameter (short axis in m). Cross section length for spheroid.

Value

numeric silhouette area as a proportion.

References

Campbell GS, Norman JM (1998). Introduction to environmental biophysics, 2nd ed. edition. Springer, New York. ISBN 0387949372.

See also

Other allometric functions: mass_from_length(), proportion_silhouette_area(), surface_area_from_length(), surface_area_from_mass(), surface_area_from_volume(), volume_from_length()

Examples

  proportion_silhouette_area_shapes(shape = "spheroid", 
                                    theta = 60,  
                                    h     = 0.01,  
                                    d     = 0.001)
#> [1] 0.2748564
  proportion_silhouette_area_shapes(shape = "cylinder flat ends",  
                                    theta = 60,  
                                    h     = 0.01, 
                                    d     = 0.001)
#> [1] 0.2744423
  proportion_silhouette_area_shapes(shape = "cylinder hemisphere ends",  
                                    theta = 60,  
                                    h     = 0.01, 
                                    d     = 0.001)
#> [1] 0.2733313