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

V-Ray for SketchUp
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Another important option with Light Cache is the Sample Size. This is used to determine the size of each 
sample. A smaller number will yield more detail and a sharper image, where a larger number will loose some 
detail but have a smoother result. 
With each of these images the primary and secondary bounces are calculated with Light Cache. The images 
on the left has a sample size of .02 and the images on the left has a size of .03. With both cases the top image 
is the result at the end of the Light Cache calculation and the bottom image is the rendered result.
It is important to note that Light Cache is not appropriate to be used for primary bounces, as it does not 
produce smooth results or good details. It is only being used as a primary bounce in this case to illustrate the 
difference in sample size 
Scale in Light Cache
In order to determine the size of each sample, Light Cache gives itself a scale to work with. The default 
setting for scale is Screen. This means that each sample is a percentage of the image. The default value is 
.02, or 2 percent. Which means that the size of each sample is approximately 2 percent of the total image.
It is possible to use the scene units to determine the size of the samples. To do this change the scale to 
World, and now the sample size is in scene units. The advantage to using screen units over world units is that 
with screen units more samples will be added to objects which are in the foreground of the image. With 
world units many samples will be added to objects far away, while objects which are closer to the camera will 
receive fewer samples. Because of this issue it is recommended to keep the scale at the default value of 
screen. 
V-Ray for SketchUp
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Point Light
Rectangular Light
Below are all light types
' 
details
supported by V-Ray for SketchUp. Each light
'
s content is different. 
Other then color, multiplier and shadow on/off, each also has Subdivs for shadow quality control, 
Photon Map for render quality control, Caustic Subdivs control and Bias for shadow offset. The 
difference is
only with
Point
Light
which has the ability
to
adjust
the
radius
of
shadows
.
Point Lights are the ones that need to control the Decay itself: Linear, Inverse and Inverse Square.
The last two Decay dramatically. So when using Inverse or Inverse Square, you must increase the 
multiplier. That means Point Lights are very much affected by the distance from an object, so it 
will take longer time to adjust these lights.
Lighting Dialog Box