9.5.2

354 • CHAPTER 7
OBJECTS MENU • LIGHTING • 355
Outer Distance, Relative Scale
Between the Inner Distance and the Outer Distance the density of the visible light changes from 100%
to 0%. When using spotlights, modify the scale of the Outer Distance value along each axis using the
three Relative Scale text boxes.
Sample Distance
The Sample Distance is relevant for visible volumetric lights. Adjusting this value denes how nely
the visible light’s volumetric shadow will be computed. Larger values lead to a somewhat rough (but
swift) calculation, while smaller values lead to a much ner, but more time-consuming, result.
Take care with the Sample Distance values. Finding a happy medium (small for
ne detail, but as large as possible for reducing render time) is the key here.
The value of this Sample Distance is measured in world units. This value thus determines how nely the
shadows within a visible light will be sampled. Values will usually be from 1/10th to 1/1000th of the
light source radius. By increasing the value your scene will render noticeably faster but certain parts
of your scene will be sampled very roughly, resulting in sampling artefacts. To reduce these sampling
artefacts requires a reduction in your sampling value too. The smaller the value, however, the higher
the cost in rendering time.
CINEMA 4D contains an integrated antialiasing technique for surface shine, ensuring even the roughest
surfaces render smoothly, allowing you to set the Sample Distance value somewhat higher than
without this feature.
Sample Distance tips
To produce ne shafts of light, such as those produced when light beams radiate through cracks or
from behind stone columns, set the Sample Distance to a relatively low value. On the other hand, a
light that is completely covered and allows no beams of light to break through may be sampled at a
much higher value. To clarify this, here’s a small example; the pumpkin in the pictures below has a
radius of 150 units, the visible volumetric light a radius (Outer Distance) of 700 units.
From left to right: Distance: 10. Render time: 105 s. The volumetric light looks perfect. /
Sample Distance: 20. Render time: 60 s. Here the rays emitting from the mouth and the right eye are
showing the rst signs of artefacts. / Sample Distance: 40. Render time: 35 s. You can clearly see now
how the rays in the visible light are losing their ne edges. / Sample Distance: 80. Render time: 23 s.
The picture has, quite literally, been rendered useless.