492
AutoCAD and Its Applications—Advanced
Copyright Goodheart-Willcox Co., Inc.
Lighting Units
There are three types of lighting units available in AutoCAD: standard (generic),
American (foot-candles), and International (lux). Generic lighting is the only type of
lighting that was used in AutoCAD prior to AutoCAD 2008. This lighting provides
very nice results, but the settings are not based on any real measurements. American
or International lighting is called photometric lighting. Photometric lighting is physi-
cally correct and attenuates at the square of the distance from the source. For more
accuracy, photometric data fi les can be imported from lighting manufacturers.
The
LIGHTINGUNITS
system variable sets what type of lighting is used. A setting of
0 means that standard (generic) lighting is used. However, for more realistic lighting, it
is recommended that photometric lighting be used. A setting of 1 or 2 results in photo-
metric lighting. Entering a value of 1 specifi es American lighting units. A setting of
2 specifi es International lighting units. This is the default setting. The only difference
between a setting of 1 and 2 is that American units are displayed as foot-candles (fc)
and International units are displayed as lux (lx).
Sunlight and Location
To turn sunlight on or off, pick the
Sun Status
button in the
Sun & Location
panel on
the
Visualize
tab of the ribbon. Refer to Figure 17-6. This button is blue when sunlight is
on. Sunlight can also be turned on or off in the
Sun Properties
palette, which is discussed
in the next section. Sunlight is not represented by a light glyph. The date, time, and
geographic location can also be set in the
Sun & Location
panel on the
Visualize
tab of the
ribbon. These properties determine how the scene is illuminated by the sun.
To change the current date, drag the
Date
slider left or right. Sunlight must be on for
the slider to be enabled. As you drag the slider, the date is displayed on the right-hand
end of the slider. The time is changed in the same manner. Drag the
Time
slider left or
right. As you drag the slider, the time is displayed on the right-hand end of the slider.
The location of the scene can be set to an actual geographic location. This is impor-
tant if you want to replicate the lighting and shadows of an actual site. The
Set Location
drop-down list on the
Sun & Location
panel on the
Visualize
tab of the ribbon provides
two options for setting the location of the scene:
From Map
and
From
File. The
From
Map
option allows you to select a geographic location from the Autodesk online maps
SUNSTATUS
Ribbon
Visualize
Sun & Location
Sun Status
Type
SUNSTATUS
GEOGRAPHICLOCATION
Ribbon
Visualize
Sun & Location
Set Location
From Map
Type
GEOGRAPHIC-
LOCATION
GEO
NORTH
NORTHDIR
Pick to toggle
default lighting
on and off
Brightness
Contrast
Midtones
Pick to toggle
display of
light glyphs
Pick to
open
Lights in
Model
palette
Lighting units
Pick to open the
Sun Properties
palette
Pick to create
user-created
lights
Pick to toggle
sunlight on
and off
Date and
time
Sky
setting
Pick to set
the geographic
location
A B
Figure 17-6.
The tools for adding and controlling lights. A—Tools in the
Lights
panel of the
Visualize
ribbon tab. B—Tools in the
Sun & Location
panel of the
Visualize
ribbon tab.