2012

Table Of Contents
same amount of light shines upward and downward. No point has a very large
X or Y component, either positive or negative, so less light is cast laterally
from the light source.
IES Standard File Format
IES standard file formats can be created and modified.
You 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 for Mac 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).
The 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:
1 IESNA91
2 [TEST] The test report number of your data
3 [MANUFAC] The manufacturer of the luminaire
4 TILT=NONE
5 1
6 The 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
lamp ratings.
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