Autodesk LIGHTSCAPE, Manual

Page: 169 / 362

Interior Model Considerations
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2.
Click the Processing tab.
3.
To instruct the sun to cast shadows, enable Cast
Shadows in the Sunlight group box.
4.
To instruct the light from the sky to cast shad-
ows, enable Cast Shadows in the Sky light group box.
5.
Click OK or Apply to accept the processing op-
tions.
For more information on enabling shadows, see
“Setting Daylight Processing Parameters” on page
165.
To enable shadows and adjust their accuracy in the
radiosity solution:
1.
Choose Process | Parameters.
The Process Parameters dialog appears.
2.
In the Process group box, enable
Daylight (su sky light).
3.
Enable Shadows.
4.
Adjust the Sky Light Accuracy slider to control
the definition of shadows attributed to skylight.
A higher value results in longer processing time and
more accurate shadows.
For more information, see Chapter 11, “Radiosity
Processing.”
Interior Model Considerations
Computing the sky illumination onto the center of
an interior model requires looking for sky contribu-
tions from all directions around this center. Most of
the time, the sky is occluded by the walls and ceiling
of the model. Typically, only a few of the sky dome
sectors considered during this computation are
visible through a window.
Those sectors that are visible through a window
often only partially overlap with the window. Light-
scape, however, considers their contributions as if
they were fully visible. This can result in inaccurate
estimates of sky illumination.
To obtain more accurate and efficient results for
natural daylight in the interior of a model, you
should specify the windows and openings through
which light enters the space.
There are two points of entry through which
daylight can enter an interior model:
•
Windows
• Openings.
When you start the radiosity process, illumination
from the sky through a window or opening is calcu-
lated in advance. The window or opening is then
treated as a diffuse light source that illuminates the
interior of the room.
Although the amount of light energy emitted into
the room’s interior is correct using this method, the
directional distribution of the skylight is replaced by
a diffuse distribution. As a consequence, the ceiling