HOW to render alpha transparency in PNG using Vray RT ?

[lstan]

Hi,

 

anyone can help me, I usually render alpha in PNG using Vray Adv and the empty background will be rendered transparent,

 

but when using Vray RT, the empty background is rendered black.

 

I start a new empty scene and render PNG using Vray Adv and Vray RT, the same result the Adv gets alpha but NOT the RT. Why is this happening ?

 

How to get alpha transparency in PNG using Vray RT ?

Thanks for help

[Nicolai Bongard]

When you save as .PNG there is an option to make sure the alpha is transparent. See if that is turned off or on when you save from RT.

[lstan]

Thanks Nikolai

i contacted Chaos Group, it seemed Vray RT 3.0 and below dont support PNG alpha

[notamondayfan]

I would render the RGB and alpha pass separately, then use Photoshop (or similar) to add the transparency, and save out as a png. I would never render directly to a png file.