The number one concern for us VRay users is the act of balancing quality with rendering time. Effects like Subsurface Scattering, while nonetheless beautiful, raise rendering times immensely. But still, that doesn’t mean we need to sacrifice on such quality effects every single time. The developers at Chaos Group recognize such issues, and have placed different tools at our disposal. The venerable VRay2SidedMtl (VRay Two Sided Material) is one of these.

The VRay2SidedMtl can actually be used in two scenarios:

1. To simulate sub-surface scattering in thin plane or non-shelled meshes like leaves, paper lamps and curtains; or
2. Simply apply two different materials to the front and backface normals of a 2d mesh.

How To Use VRay2SidedMtl

The first case use is pretty much its best feature. You can easily simulate SSS for thin plane meshes without any computational penalty of the other translucency effects. Let me enumerate how you can use it in order to create realistic leaves and curtains:

1. Create a new VRay2SidedMtl and assign your main material to its front slot.
2. Do not assign any material to the back slot.
3. Use the translucency color to control the amount of light passing through the mesh. The whiter the color, the greater the material translucency.
4. You can even assign a translucency map for greater control over the areas with translucency.

VRay2SidedMtl is a material that also gives you the ability to assign a different material to the front and back faces of any mesh. The front side material gets applied to the right side normals of the mesh, while the backface gets the back material. For this you just need to check and activate the back material slot.

In this case the translucency color controls the blend between the two sides. A value of black has no change, while a white value interchanges both the materials. Any middle grey value thus signifies the blending of the 2 materials into each other.

Now in a few simple steps you can simulate translucent leaves, curtains and lamps without any drastic increase in rendering time. If you want to see more examples for this material, check out this official resource.

I hope you found this tutorial helpful, and if you did, you’ll find my other tutorials equally helpful. Share and Comment, guys. Talk soon.