2013

Table Of Contents
14 The set of vertical angles, listed in increasing order. If the distribution
lies completely in the bottom hemisphere, the first and last angles must
be 0° and 90°, respectively. If the distribution lies completely in the top
hemisphere, the first and last angles must be 90° and 180°, respectively.
Otherwise, they must be 0° and 180°, respectively.
15 The set of horizontal angles, listed in increasing order. The first angle
must be 0°. The last angle determines the degree of lateral symmetry
displayed by the intensity distribution. If it is 0°, the distribution is axially
symmetric. If it is 90°, the distribution is symmetric in each quadrant.
If it is 180°, the distribution is symmetric about a vertical plane. If it is
greater than 180° and less than or equal to 360°, the distribution exhibits
no lateral symmetries. All other values are invalid.
16 The set of candela values. First, all the candela values corresponding to
the first horizontal angle are listed, starting with the value corresponding
to the smallest vertical angle and moving up the associated vertical plane.
Then, the candela values corresponding to the vertical plane through
the second horizontal angle are listed, and so on until the last horizontal
angle. Each vertical slice of values must start on a new line. Long lines
may be broken between values as needed by following the instructions
given earlier.
Example of Photometric Data File
The following is an example of a photometric data file.
726 | Chapter 13 Render Drawings