How do I make a translucent shader using mia_materialX???

[Kelvin Luo]

Hello,
How do I adjust the mia_material X to be translucent. I can see there is a translucent attr in the shader, and transparency. But I am kinda confused of their relationship. For example, if I am making a piece of paper translucent, allowed a light from behind to do the scattering effect? I dont want to use SSS shader to do the trick. How do I adjust the materialX shader to have this effect?And a detail explanation of the relationship between translucet and transparency would be better.
thank you

[rebazcg]

To create what you are asking, a translucent paper:
1. Create a plane ( or any object that resembles a paper)
2. Create a spot light then point the spot light to that paper ( the plane)
3. Then assign an mia_materialX to the plane.
4. Go to the Translucency section, in the mia_matreialX and tick the box Use Translucency.
5. Change the color to white and the weight to 1.
6. If you render the image, you will no Translucency effect on the plane, why? because there are no transparency and without some transparency, there will be no translucency.
7. Go to the Refraction Section and enter some value to the transparency, to make the object transparent, then render the image and you should be able to see the translucency effect on the plane.

Simply to make you understand transparency: it helps you see through the object, which means increasing transparency, will increase the ability to see through the object more clearly. An example of transparent object is a clean and clear glass.
Simply to make you understand translucency: it does not let you see through the object but only let the light to pass through the translucent object , so we are only able to see the light and but not the other objects in the scene. To make it work the object should also be a little transparent so as to let the transparency work. An example of translucent object is a thin and clean fabric or piece of cloth .

[Kelvin Luo]

thx for the reply, but I already know this part. So what does the weight of the translucent do? cuz seems the transparency control the degree of the translucent already.And also ? can I use this set up for candle or wax ? Since the SSS is kinda expensive to render , just finding a alternative way to achieve a closed look result. but Thank you very much still

[dan]

While this course doesn't use an mia_material_x, this might help: http://www.digitaltutors.com/11/training.php?pid=306

[Kelvin Luo]

thx Dan, Sorry my main question is not about how to set up a translucent shader for a paper. It more about what is the relationship between translucent weight and transparentcy in mia_material X.

[rebazcg]

Let me point out a few lines from the documentation, hope this can help:

The mental ray mia_material is a monolithic material shader that is designed to support most materials used by architectural and product design renderings. It supports most hard-surface materials such as metal, wood and glass. It is especially tuned for fast glossy reflections and refractions (replacing the DGS material) and high-quality glass (replacing the dielectric material).

From the above line, we will know that it is meant to be used to create hard surface materials not materials like skin or candle.

Waxed floors, frosted glass and brushed metals... - ...all fast and easy to set up.

But still can be used for making waxed floors such as SSS marble, but personally still prefer SSS material to make such kind of surfaces.

Translucency is handled as a special case of transparency, i.e. to use translucency there must first exist some level of transparency, and the refr_trans_w parameter decides how much of this is used as transparency and how much is translucency:

If refr_trans_w is 0.0, all of the transparency is used for transparency.
If refr_trans_w is 0.5, half of the transparency is used for transparency and half is used for translucency.
If refr_trans_w is 1.0, all of the transparency is used for translucency and there is no actual transparency.

while the refr_trans_w = the "weight" of translucency you are talking about.



As you can see Solid( the glass on the left) vs. Thin-walled ( the bubble in the middle) transparency and translucency (the doll on the right)

For more detials on this feature and all the other features of mia_material X, you can read the below link:
http://docs.autodesk.com/MENTALRAY/2...mia_material_x