Surface
(Term used in the Radiance software)
Radiance defines all geometry by means of surfaces.
There are a number of different surface types,
most of which have a front and a back side.
The types are defined as follows:
- source
-
This a virtual surface that should rather be thought
of as a solid angle.
It is defined by a direction and a diameter in degrees,
and is used for specifying light sources that are very distant.
- polygon
-
This is the most common surface type. It is defined
by three or more coplanar points. The surface normal
is determined by the right hand rule.
- ring
-
A ring is a circular planar disk, possibly with a hole
in the center. It is defined as a center point,
the surface normal, the inner radius, which may
be zero, and the outer radius.
- sphere
bubble
-
Spheres and bubbles are defined by a center point
and a radius. A sphere has the surface normal to the
outside, a bubble to the inside.
- cone
cup
-
Cones and cups are megaphone shaped objects, truncated
by two planes perpendicular to their axis.
They are defined by two endpoints and a starting and
endigh radius, one of which may be zero.
A cone has the surface normal to the outside,
a cup to the inside.
- cylinder
tube
-
Cylinders and tubes are similar to cones and cups,
but their starting and ending radii are equal.
