Autodesk LIGHTSCAPE, Руководство пользователя

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Processing Workflow
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Progressive Refinement
Lightscape computes the simulation in successive
iterations. At each iteration, the system selects the
brightest light source and computes its contribution
to all the surfaces in the scene. Once the primary
light sources are accounted for, the system computes
the inter-reflections of light between surfaces,
selecting the brightest reflecting surface at each
iteration.
This process is called progressive refinement because
the system refines the radiosity solution at each iter-
ation—that is, each iteration is a better
approximation of the final result.
In principle, the refinement process continues until
it accounts for all the multiple inter-reflections of
light. In practice, however, the simulation converges
rapidly toward the final result, so that visual differ-
ences between successive iterations become
unnoticeable after only a fraction of the surfaces (but
the most important of them) have reflected their
light contribution back into the environment.
Ambient Approximation
Because each progressive refinement iteration adds
light to the environment, displaying the radiosity
solution during processing initially shows a dark
scene, which becomes brighter with every iteration.
Instead of displaying only the completed light after
each iteration, the system can add a rough approxi-
mation of the yet uncomputed lighting, so that the
average brightness of the scene is approximately the
same after every iteration. When you use such an
ambient approximation during display, the lighting
of the scene initially appears very flat and uniform;
but at each iteration the system replaces this coarse
approximation with a more accurate solution and all
the subtle variations in lighting typical of radiosity
solutions.
Processing Workflow
The accuracy, speed, and memory usage of a radi-
osity simulation are controlled by a number of
parameters, organized into two main groups: global
controls and local controls.
First, you must set the processing parameters , or
global controls, which affect the simulation over the
entire scene. If required, you next set the
surface
processing parameters
, or local controls, which only
affect the processing of a particular surface or group
of surfaces.
Once you have set the processing parameters,
initiate the model to move from the Preparation
stage to the Solution stage. During this step, Light-
To compute a solution, you must first specify the light sources, materials, and texture maps associated
with the surfaces in the environment. You define this data for a model during the Preparation stage.
Once you initiate the model for processing (convert it to a Solution file), you can no longer create or
reposition any surfaces or light sources. All modifications of this nature must be performed during the
Preparation stage.
During the Solution stage, you can modify the characteristics of light sources and materials at any time;
the simulation compensates for the resulting changes in illumination. This feature promotes an inter-
active approach to design, so you can quickly evaluate and make refinements to obtain precisely the
look you want.
Moving from Preparation Stage to Solution Stage