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60 Chapter 17: Rendering
6.
In the Interactive Tools group of the Radiosity
Processing rollout, click Setup to display the
Environment panel (page 3–272),whereyouset
exposure controls.
7. When working with non-physically based
lights, a lways use the Logarithmic Exposure
Control (page 3–297).OntheLogarithmic
Exposure Control rollout, select Affect Indirect
Only.Thiswillcausetheexposurecontrolto
affect only the results of the radiosity solution.
By doing so, you will maintain the way your
direct lights render without radiosity. Use
the Brightness and Contrast controls of the
exposure control to adjust the intensity of the
radiosity solution to match the lighting at an
appropriate level.
Tip: You can use the thumbnail preview to adjust
brightness and contrast interact ively.
8. Click Render Scene to render the scene
after radiosity processing.
Summar y
The following table will help you obtain good
results with radiosity.
Physically Based
Workfl ow
Non Physically
Based Workflow
Lights Photometric Lights
(page 2–1301)
Standard Lights (page
2–1288)
Daylight
IES Sun (page 2–1309)
and IES Sky (p age
2–1312)
Directional Light
(page 2–1292)
and Skylight (page
2–1296)
Exposure
Control
Any
Logarithmic (page
3–297)
turn on
Affect Indirect Only.
Units
Make sure your
scene is set to the
appropriate scale.
Make sure your
scene is set to the
appropriate scale.
Animation with R adiosity
By default, a radiosity solution (page 3–51)
is calculated at the current frame. If you are
animating objects and you want to perform a
radiosity solution at every frame, select Compute
Advanced Lighting When Required in the
Render Scene dialog > Render panel > Common
Parameters rollout (page 3–27) >Advanced
Lighting group.
Once the renderer starts processing each frame
of your animation, the radiosity solution will be
computed for each f rame as required. This occurs,
forexample,whenanobjectmoves,oralight
intensity changes. If nothing changes in the scene
from one frame to the n ext, the radiosity engine
will not recalculate the solution.
Note: Due to the random statistical sampling u sed
by the radiosity engine, there might be some
flicker ing between f rames. If this occurs, increase
the value of Initial Quality or the number of Refine
Iterations to solve the problem.
Tip: Before launching a lengthy animation with
radiosity, you should process a radiosit y solution
manuallyforasingleframetomakesurethe
results are acceptable.
Tip: If you animate only your camera (as in
an architectura l walkthrough) then you can
calculate a radiosity solution for only the first
frame of the animation, and reuse it in all
subsequently rendered frames by tur n ing off
Compute Advanced Lighting When Required on
the Common Parameters rollout of the Render
Scene dialog .
Avoid using the A u tomatic Exposure Control (page
3–295) for animations. This exposure control can
change from frame to f rame, creating a flickering
effect.