The Alpha Render Element shows the transparency of objects in the scene as grayscale colors. Solid geometry is represented by solid white, while those areas not blocked by geometry within the scene are black. Pixels at antialiased edges have varying shades of gray, as do semi-transparent surfaces.
||Render Setup window||> Render Elements tab > Addbutton >VRayAlpha
Column
width
5%
Column
width
45%
...
Fancy Bullets
type
circle
When using transparent materials such as glass, make sure that the material is set up to treat the material as transparent with regard to the Alpha channel. For example, when using VRayMtl as the material, set the Affect channels parameter for both Reflection and Refraction to Color+alpha or All channels. Otherwise, the transparent surface will is not be treated as transparent in the Alpha Render Element.