Relative scale/size of Phoenix/Max objects

[TL4500]

Hi.

In order to create a render of the flames with a transparent background I have tried giving all the objects in the scene a VRayWrapper material and making this "matte" and the Alpha -1. When I render to a TGA file the background is black rather than transparent.

Has anyone any ideas what settings I need to change in order to correct this?

Thanks,

Terry

[Svetlozar Draganov]

Hi.

In order to create a render of the flames with a transparent background I have tried giving all the objects in the scene a VRayWrapper material and making this "matte" and the Alpha -1. When I render to a TGA file the background is black rather than transparent.

Has anyone any ideas what settings I need to change in order to correct this?

Thanks,

Terry

What Ivaylo is trying to say is that you do not need to prepare a special setup in order to extract only the flames.
You could very easily extract only the flames with the help of VrayAtmosphere Render Element - these Render Element could be saved just like RGB pass.

Here is a screen-shot how to enable VrayAtmosphere Render Element:

[TL4500]

Thank you.

I can now see what Ivaylo meant by setting atmospherics in Render elements tab and from dropdown in the VRay frame buffer. I have done this and I have a render that shows just the flame components.

Now, when I save this file to TGA and tick "Pre-multiplied alpha" the resulting file has a black background not transparent.

Could you please explain how I either:

1. render the above with transparent background OR
2. save the TGA with transparent background


Many thanks,

Terry

[TL4500]

Hi.

Further to all this:

I have been trying to fugure out why the alpha channel is missing from the flames TGA file. After a lot of asking and testing I am pretty sure that this is to do with the VRay/Phoenix object render.

If I render off part of the geometry (RGB) from the same file and save as TGA with Pre-multiplied alpha ticked, I get the geometry with a transparent background.

If I render off the flames using the VRay Render element Atmospherics as we have discussed, the resulting TGA file does not have a transparent background.

This would lead me to think there is a setting somewhere to correct this?

I am desperate to solve this as I have a deadline looming and a lot of frames to render.

Many thanks,

Terry

[Ivaylo Katev]

in vray the render elements do not have separate alpha channel, you have to add the atmosphere render element in the compositing, not to blend it using alpha.
this is the idea of the premultiplied alpha, the fire is multiplied by the alpha before the export, and now you have only to add the atmosphere to the background and this automatically produces correct blending

[TL4500]

Thanks Ivaylo, I think we are finally there!

Many thanks for all your help!