Rendering transparent objects with alphachannel

Rendering transparent objects with alphachannel

Hi all, how can i fix this?
I am trying to render a transparent glass-object, and i want an alphachannel that handles the transparancy of the glass. So that i can superimpose the rendered object over a background in Photoshop.

An example would be a lightbulb rendered with an alphachannel that contains alle the nontransparent elements of the bulb.

I guess what i am asking is to render the glass-object without a background...

Jan Atom

Hi Jan.
You can try this:
Put a pure white tiff into the HDR tag. Render and save to xyz.png. In your bitmap editor say white to transparent. Copy&paste in your target pic. Something like that?

With kindest regards
Frank

Yes! something like that.

Thanks alot Frank, that was a quick hack that works!
I was more hoping for an alphachannel to eliminate the background, and not use blendingmodes in PS.

So next question: What happens if i have white objects inside the bulb.

Would it be possible to render the background as transparent, and generate an alphachannel like that?

Jan Atom

Jan Atom said:

.. that was a quick hack that works!
I was more hoping for an alphachannel to eliminate the background, and not use blendingmodes in PS.

Click to expand...

I know:redface: But it isn´t yet possible and hopefully will be covered by the new texture system Martin is working on.

Jan Atom said:

So next question: What happens if i have white objects inside the bulb.

Click to expand...

It should work the same way, BUT I´m pretty sure the white objects won´t appear as "white" objects anymore.

Would it be possible to render the background as transparent, and generate an alphachannel like that?

Click to expand...

No.

With kindest regards
Frank

I've described this workaround several times already, but here it is again in tutorial form. Note that I imagine v5 will fix this longstanding issue.