9

1326 Chapter 15: Lights and Cameras
Free Area Light (Photometric) (page 2–1309)
Intensity/Color/D i stribution Rollout (page 2–1352)
Web Parameters Rollout (page 2–1355)
IES Standard File Format ( page 2–1328)
Procedure
To cr eate a light from a manufacturer ’s I ES f ile:
1.
OntheCreatepanel,clickLights.
2. Choose Photometric from the drop-down list.
(The default is Standard.)
3. In the Object Type rollout, select any
photometric light type.
4. In the Intensity/Color/Distribution rollout,
select Web from the Dist ribution list.
5. If you are creating a Target Point, Linear, or
Area light, drag in a view port. The i nitial point
of the drag is the location of the light, and
thepointwhereyoureleasethemouseisthe
location of the target. If you are creating a Free
Point, Linear or Area light, click i n a v iewport
to position the light.
A light is created using the default photometric
web which is a diffuse distribution shining f rom
one edge.
6. Go to the Web Parameters rollout, and select
the IES file that you want to u se. See Web
Parameters (page 2–1355).
7. Set the creat ion parameters.
You can use the Move transform to position the
light (page 2–1282).YoucanalsousethePlace
Highlight (page 1–467) command to change a
light’s position.
Ph otometr ic Webs
Lightthatusesaphotometricweb
A photometric web is a 3D representation of
the light intensity distribution of a light source.
This directional light distribution information is
stored in a photometric data file in the IES format
using the IES LM-63-1991 standard file format
(page 2–1328), or in the LTLI or CIBSE formats
for photometric da ta. You can load photometric
data files prov ided by various manufacturers as
web parameters (page 2–1355).Thelighticon
represents the photometric web you select.
To describe the directional distribution of the light
emitted by a source, 3ds Max approximates the
source by a point light placed at its photometric
center. With this approximation, the distribution
is characterized as a function of the outgoing
direction only. The luminous intensity of the
source for a predetermined set of horizontal and
vertical angles is provided, and the system can
compute the luminous intensity along an arbitrary
direction by i nterpolation.