Specular reflection in external surfaces--Algorithm 1.43

A specular reflection of the sky can occur in glossy external surfaces, such as a glazed curtain wall. If the reflected sky zone includes the sun, glare or overheating can be caused.

The same equations may be used to trace the reflection of rays in an interior.

a. Direction of a reflected ray

Input
Direction cosines of the original ray or line of sight,
Direction cosines of surface normal, (algorithm 5.12)

Equation
The direction cosines of the reflected ray are

Source
General theory of analytic geometry
b. Luminance of reflected sky, Lv'
Input
Luminance of sky zone, Lv
Direction cosines of the original line of sight,
Direction cosines of surface normal, (algorithm 5.12)
Specular reflectance of the surface at angle of incidence q, r'(q)

Equation

Source
General theory of analytic geometry


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