Autodesk LIGHTSCAPE, Manual

Page: 189 / 362

Initiating the Model
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This parameter scales the minimum and maximum
mesh spacing for the selected surfaces. If the global
minimum value is 12 inches, setting this parameter
to 2 decreases the mesh resolution by dividing the
global minimum in half (to 6 inches) and applying it
locally to the selected surfaces. The maximum mesh
value is also halved. In addition, the global Subdivi-
sion Contrast Threshold is decreased, making it
more likely that the system will subdivide the mesh
elements to capture illumination details cast over the
surface.
Setting this parameter to a value less than 1
decreases the likelihood of triggering the mesh
subdivision process.
No Mesh
Use No Mesh to control whether mesh subdivision
on a surface is allowed. Enable this parameter to
disallow any mesh subdivision on the surface.
Reset Mesh
Use Reset Mesh to reset the radiosity mesh of a
surface to its coarsest state, with all the illumination
values at its vertices set to 0.
Initiating the Model
Before you can begin the radiosity processing, you
must
initiate the model. Initiation converts the data
describing the surfaces and light sources in the
model to a more efficient form for radiosity
processing.
▲
Once the system completes this conversion,
you can no longer create or reposition any surfaces
or light sources. You must make any such changes
to the original Preparation model and reinitiate the
model. Consequently, you should always save your
Preparation model before initiating it.
Note: For large models, the initiation process may
be completed more quickly by making sure that no
one layer contains a large number of input
surfaces.
To initiate the model:
Choose Process | Initiate, or click the Initiate
button
.
The Solution model replaces the Preparation model
in the Graphic window.
After initiation, every surface in the model has a
radiosity mesh with an illumination value of 0 at
each of the mesh vertices. The model appears
dark—light is propagated through the scene once
you begin processing. You can enable
Ambient
to approximate the effect of undistrib-
uted light energy in the environment before
processing.
Note: From this point on, you save the data as a
Solution file with a .ls extension rather than as a
Preparation file with a .lp extension.
Results of Initiating the Model
Although the initiation process does not change the
form or surface characteristics of the objects in the
scene, it substantially transforms the underlying
data representation. The main changes that occur
during this process are described in the following
sections.
Model Hierarchy Is Flattened
The initiation process flattens the model hierarchy
and explodes all instances in the model into indi-
vidual surfaces.
The system stores the illumination values on the
surfaces themselves. Since instances of the same
block may have different illumination values, their
surfaces need to be explicitly defined.