Alpha channels through transparent material

[richflem]

I would like to render out a tiff or png with a transparent background behind clear plastic. I'm currently working on some eyewear and would like to drop the image onto various backgrounds. This subject was discussed in a previous blog post by Josh, but the link explaining the method is broken http://keyshot.com/keyshot-alpha-channels-two-tuts-for-transparent-backgrounds/2011/

The image from the blog post (below) describes exactly what I would like to achieve, but in Keyshot, is it possible?

If it isn't possible in Keyshot could someone please give me some pointers to achieving the same result in Photoshop?

Thanks

[feher]

You need to select ethier a .tiff with alpha boxed checked or png with alpha boxed checked. in your rendering window set up.
Tim

[Al Baldi]

The render settings will affect the alpha, but so will the materials.

I've found that using Glass is the best for reliable alphas on transparent materials.  Even when making a foggy plastic and sometimes even liquids I use Glass.  There are certain "transparent" Keyshot materials that do not produce an alpha, instead they render your transparent materials + the background and flatten them together.

Below you can find a chart that shows all of the transparent materials and what kind of alpha they produce.

[PhilippeV8]

Euh .. I SHOULD have that lightbulb-greenkey tutorial printed out at work ... If I don't forget, I'll look it up tomorrow and try to scan it into a pdf ... I remember it is sort off a long way round with PS tricks .. but it does work very well.

[Chad Holton]

Here you go: http://keyshot.com/forum/index.php/topic,951.0.html

I tested the link, to the actual tutorial posted in the thread, and it's still good.

[PhilippeV8]

Thnx Chad, that works indeed and saves me a couple of minutes 

[Al Baldi]

Do other versions of Keyshot not have the Glass material with transparency?  I can't imagine having to go through that many hoops for every render that needs a transparent alpha channel.