VRay for SketchUp Manual
Chairs-Refraction-Original.skp. We are going to
introduce how to add and edit the refraction layer. Select the red chair from
above. Select "Materials Editor" icon over V-Ray toolbar to edit chair material.
Add Refraction Layer
1. Click on the "+" to the right of the
Chair_Red, and then right click on Refraction Layers. Select Add new layer. You
will see the Refraction layer added to the right of the window.
Controlling the amount of transparency
2. If you don't see the transparency from
the material preview window, that's because the Transparency is set to black.
Use this color to adjust the degree of Transparency. Click on the color and
change it to white, which will give you 100% of transparency to the material.
3. Click on the Update Preview again and
you will see the transparency, but without its original red color. When you set
the transparency to 100% white, no matter what you have for diffuse color, it
will not show up. It will render like the image at the bottom.
color of refractive materials
When you want to apply color to a refractive material, the best way to do
this is through the Fog Color, which is located to the lower right of the
Refraction dialog box.
4. Click on Fog Color and change it to
the same color as the original Diffuse Color. Click on the Update Preview and
you will see the red color show up on the material this time.
Image on the left is what you will get. Do the same changes to the other two
colors and you will get the image looks like the one to the right. Under Render
Environment, change the background color from black to white and see what you
will get this time.
The appearance of Fog depends on three parameters; Fog color, Fog Multiplier,
and object size. The Fog color is a very important factor, and the wrong color
can make it hard to achieve your desired effect. It is best to set your color to
a very light or desaturated version of the desired color. The Fog multiplier
will be determined by the Fog color and the object size. The object’s size is
important because Fog is created by calculating how much light penetrates an
object. Therefore, a larger object will absorb more light than a smaller object.
This means that a single setting will not necessarily produce the same effect
from object to object. The image below is two spheres with the same
material applied to them, but the sphere on the right is 4 times larger. The
images below are tests of different multipliers with a saturated and desaturated
Fresnel IOR: 1.55
Refract IOR: 1.55
Fog Color: R244, G250, B230
Fresnel IOR - 1.55
Refract IOR - 1.55
IOR - 1.55
Fog Color - R175, G250, B0
with Index of Refraction
IOR (Index of Refraction) is used to calculate among of the light refracted
from a transparent object. The newly added IOR default is set to 1.55. Please see
the chart for typical objects' IOR value.
Default set the Refraction IOR to 1.55; please refer to the images below for
setting the IOR to create your desired material.
Please note that reflection and refraction IOR values are separate, but to
achieve an accurate effect these values should be the same.
Glossiness of Refractive materials
Both refractive objects and reflective objects have an option setting for
Glossiness. The difference is that Reflection Glossiness only affects the
surface, whereas Refraction Glossiness will have an effect on the object’s
The Glossiness of a refractive object is usually used to represent different
type of glass, for example, frosted glass. The refractions will become more
blurry as the value is decreased, and at a certain point these refractions will
become so blurry that they prevent what is behind the object from being
Refraction Glossiness default is set to 1.00, please refer to images below
for impacts on different settings of Refraction Glossiness.
Images below set the Refraction IOR to 1.55, you can see the Glossiness
changes gradually from 0.85. It changes rapidly between 0.80 and 0.75. When the
setting for Refraction Glossiness remains the same, different Refraction IOR
will change the Glossiness of the object.
Just like the intensity of the Fog Multiplier affects its transparency, the
Refraction Glossiness in thicker objects becomes more obvious.
Image below shows the influence of Refraction Glossiness material to objects
behind it. Objects further away become very blurry.
There is an Affect Shadow option to the right hand bottom corner of the
Refraction dialog box, default is unchecked. When checked, the color of the
transparent object will affect its shadow and it's not black anymore. The shadow
also becomes more depth as well.
It is recommended to always have Affect Shadows checked, as it produces a
more realistic effect.
Images below show the difference with and without the Affect Shadows checked.
Under Options of each material, you will find this Double-sided selection.
Default setting is checked. This option is particularly important for
transparent material. When this option is unchecked, light that enters the
inside surfaces will not be rendered and show up black. The reason to have this
option is that sometimes you may want to uncheck this option when render object
with translucent material in order to get the right texture.
Unless you want to create some special effects, please have this option
The double sided option will not have any affect on the shadows of the
We've talked about changing the Diffuse color to get the degree of
transparency we want to create before. White means 100% transparent, black means
100% opaque. You can create translucent materials with colors anywhere between
white and black. But now we want to introduce a different translucent material.
It is related to special light absorption materials.
Open file: Translucency.skp and render
it, you will get image like below. You will see that colors where
partitions meet the outside box and at the base of the box are darker. This is
because the thickness of the object changes and the light travel distance
changes also. So the degree of light absorption varies. To create this kind of
material, you have to check the Translucency option under the Refraction.
Check the Translucent box under Translucency first. Thickness is for control
of light pass through the object, the unit for this is unclear. Keep these three
settings as default. Other items required to change include:
1. Double-Sided must be unchecked so the
light can get through to the inside of the object. This setting is extremely
2. Change the IOR to 1.
3. Decrease the Refraction Glossiness to
a value below 1.
4. Do not use white color for the
Transparency because that will turn the object to completely transparent and
become dark after rendered due to absorb too much light. Do not use black color,
either. That will not allow light get through the object at all. Pick a color
anywhere between Val 80~150 will give you the best result.
Many rendering engines use Sub-Surface Scattering (SSS) to create this kind
of material. This material is good for creating things like: wax, skin, milk,
cheese, plastic and jade which all have a little translucency in it.
Translucency is created by absorbing light to the object's surface so the
color of the object will show up a little darker than its original color. If you
still think that it's too dark even though the original color is set to the
highest Val 255, the best way to fix it is increasing the intensity of your
light in the scene.
Below are some examples.