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Chapter 8. Physics on Geometry, BRDF, Monitor Luminance,
etc.
In this new chapter some basics about the physics and made approaches are described, as well as
the used angles, some reflection and scattering models etc.
8.1. Geometry
The following sketch visualizes the used geometry, this is intended to show the parameters and
achieve geometrical motivated approaches for some different BRDF models. The light comes from
the left, intersects with the road surface (middle) and is detected by the observer (right).
hi,o are the heights of the light-source and the observer, zi,o are the horizontal distances (along the
road surface). N is the normal of the road surface at the intersection point, I and O are the vectors
pointing towards the light-source and the observer, respectively; ϑi,o are the respective included
angles.
Figure 8.1: A sketch of the scattering process
dLo
~ = fr (ϑi , ϑo )
→ fr (~I, O)
dEi
1
R 1
~ =R
default BSDF : fr (~I, O)
=
~ >
π < ~I, N
π cos ϑi
1
1
R
~ =R
Lommel − Seeliger : fr (~I, O)
=
~
~
~
~
π < I, N > + < O, N >
π cos ϑi + cos ϑo
BSDF :
(8.1)
More precise the differential ratio in the first equation has to be determined pixel by pixel for each
point on the road surface.
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