Autodesk LIGHTSCAPE, Manual

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309
E
IES Standard File Format
This appendix describes the IES LM-63-1991 standard file format used for
creating photometric data files. Only the information relevant to Lightscape is
described.
The luminous intensity distribution (LID) of a lumi-
naire 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 hori-
zontal 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 goni-
ometry are supported by the IES standard file format
but are not discussed here.
For a complete description of the IES format, see IES
Standard File Format for Electronic Transfer of
Photometric Data and Related Information
, prepared
by the IES Computer Committee.
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 inten-
sity values do not depend on different lamp ratings.
7. A 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 multi-
plying factor is 1.