U g I n f o r d e s I g n e r s

V-Ray for SketchUp
63

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Users can have a low set of values for Min and Max Rate to render faster previews while creating the lighting 
and material setting in the scene. For example: -6 and -5 or -4 to -3. Although the quality will very not be 
good it will be okay for previews. After all settings are correct, then render with higher value to get the best 
final quality image.
Image on the left is showing Irradiance
Map
'
s last prepass for a Min/Max Rate of -3/0. The image on the right 
is the final result.
Default setting of -3 and 0 represent four passes of render job. From -3, -2, -1 to 
0. So you can see the Prepass 1 of 4 to Prepass 4 of 4 from the render process 
dialog box.
According to definitions above for Min Rate and Max Rate,
it
doesn
'
t mean that -8 
and -5 setting will have the same result of -3 and 0, eventhough each has the 
Primary Engine: Irradiance Map
It can only be used for
primary
bounces.
Open file 
and open the Irradiance Map 
control panel under Options. There is a very important setting option here related to image quality: Min Rate 
and Max Rate.
Default for Min Rate and Max Rate are -3 and 0. In this file they are currently -8 and -7. Render it and you will 
get
image
as
below
. 
Notice
that
the
calculation
speed
is
very
fast
, 
but
the
shadow
and
illumination quality are 
low. There are splotchiness and artifacts as well
Min Rate: the control of minimum sample for each pixel
. 0 
value
means
1 
pixel
as
1 
sample
. 
Value
of
-1 
means
2 
pixels
as
1 
sample
. 
Value
of
-2 
means
4 
pixels
as
1 
sample
and
so
on
. 
Smaller
value
means
fewer
amount
of
samples
been
taking
from
the
object
, 
so
the
render
qualities
of
shadow
, 
reflection
and
refraction
are
not
very
good
. 
Opposite way will result in better quality but longer render time. 
Max Rate: To control the maximum sample for each 
pixel. 0= 1 pixel uses 1 sample. 1= 1 pixel uses 4 
samples. 2= 1 pixel uses 8 samples and so on. Smaller 
value means fewer total samples used to calculate the 
light. Opposite will result in better quality but
longer
render
time
.
Chairs-Irradiance-Map-01.skp