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72 Chapter 17: Rendering
and shadows. This second option is usual ly
slower but more accurate. With Render Direct
Illumination, the radiosity solution provides only
the indirect lighting.
When Render Direct Illumination is the method
you choose, you can turn on regathering to correct
artifacts and shadow leaks. Regathering provides
the slowest but the best-quality rendering.
Note: Regatheringisextremelyintensiveforyour
CPU and uses a lot of RAM, so it might not be
practical for print-resolution images (for example,
4000 x 4000 pixels).
Inter face
Re-Use Direct I llumina tion fr om R adi osity
Solution—
3ds Max doesn’t render direct lights,
but uses the direct lighting stored in the radiosity
solution. If you turn on this option, the Regather
Indirect Illumination option is disabled. The
quality of shadows in the scene depends on the
mesh resolution. Capturing fine shadow details
mightrequireafinemesh,butinsomesituations
this option can speed up overall rendering time,
especially for a nimations, because the lights don’t
have to be recalculated by the scanline renderer.
You should use this option if you are using the
Assign Vertex Colors utility (page 2–1734).
Left: Direct light only is stored in the radiosity mesh.
Middle: Indirect light only is stored in the radiosity m esh.
Right: Direct and indirect light both stored in the radiosity
mesh (the shadows are usually very coarse).
Wa rn in g : If you choose this option but haven’t
generated a radiosity solution, rendering generates a
completely black image.
Render Dir ect I ll uminat ion—
3ds Max renders
shadows from the lights at each rendering frame,
and then adds indirect light from the radiosity
solution.Thisisthedefaultrenderingmode.
Left: Direct light calculated only by the scanline renderer.
Middle: Indirect light calculated only by the radiosity mesh.
Right: Direct and indirect light combined.
Regather Indirect I llumination—In addition to
recalculat ing a ll the direct lig hting, 3ds Max
recalculates the indirect lighting at each pixel by
regather ing illumination data f rom the existing
radiosity solution. Using this option can produce
themostaccurate,artifact-freeimages,butitcan
add a considerable amount of rendering time.
Note: If you know that you want to use the
regathering option, then typically you don’t need
as dense a mesh for the radiosity solution. Even
if you don’t subdivide the surfaces at all and do
an Initial Quality of 0%, the regather ing will
work, and might provide an acceptable visual
result (useful for quick tests as well). However,
accuracy and subtle details depend on the quality
of the radiosity solut ion stored in the mesh.