IES standard file formats
can be created and modified.
can create a photometric data file in the IES format using the IES
LM-63-1991 standard file format for photometric data. (IES stands
for Illuminating Engineering Society.) However, only the information
relevant to AutoCAD is described here. For a complete description
of the IES standard file format, see IES Standard File Format for
Electronic Transfer of Photometric Data and Related Information,
prepared by the IES Computer Committee (http://www.iesna.org).
luminous intensity distribution (LID) of a luminaire is measured
at the nodes of a photometric web for a fixed set of horizontal
and vertical angles. The poles of the web lie along the vertical
axis, with the nadir corresponding to a vertical angle of zero degrees.
The horizontal axis corresponds to a horizontal angle of zero degrees
and is oriented parallel to the length of the luminaire. This type
of photometric web is generated by a Type C goniometer and is the
most popular in North America; other types of goniometry are supported
by the IES standard file format but are not discussed here.
The photometric data
is stored in an ASCII file. Each line in the file must be less than
132 characters long and must be terminated by a carriage return/line-feed
character sequence. Longer lines can be continued by inserting a carriage
return/line-feed character sequence.
Each field in the file must begin on
a new line and must appear exactly in the following sequence:
- [TEST] The test report number of your
- [MANUFAC] The manufacturer of the luminaire
initial rated lumens for the lamp used in the test or -1 if absolute
photometry is used and the intensity values do not depend on different
multiplying factor for all the candela values in the file. This
makes it possible to easily scale all the candela values in the
file when the measuring device operates in unusual units—for example,
when you obtain the photometric values from a catalog using a ruler
on a goniometric diagram. Normally the multiplying factor is 1.
- The number of vertical angles in the
- The number of horizontal angles in the
- The type of unit used to measure the
dimensions of the luminous opening. Use 1 for feet or 2 for meters.
- The width, length, and height of the
luminous opening. It is normally given as 0 0 0.
- 1.0 1.0 0.0
- 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.
- 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.
- 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
The following is an example
of a photometric data file.