Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: SHORT CUTS on 2019-08-26, 16:57:30

Title: frosted glass and alpha
Post by: SHORT CUTS on 2019-08-26, 16:57:30

Well, i need your help again, its a very simple problem but i cant seem to get this right. Background is that i need to render a couple of windows with frosted and "dirty" glass and the client wants to be able to change the background images by himself, so i thought, not a big deal, i just render out the windows with an alpha channel and the client can simply change the background in photoshop.

But, it seems that i cant get the "frosted" effect to show up in my alpha channel, its pure black which makes it not usable. So my question would be, is there any way to render frosted glass on a transparent/black background with an alpha channel that is not pure black? What am i am missing here?

here is a render test with a bg image, this is basically how i want it too look but be able to change the background:
http://prntscr.com/oxpdq7 (http://prntscr.com/oxpdq7) and this is the alpha: http://prntscr.com/oxpe2f (http://prntscr.com/oxpe2f)

Title: Re: frosted glass and alpha
Post by: TomG on 2019-08-26, 17:28:25

The thing is that the refraction of the glass is what makes the frosted effect, and that happens at render time (so the background that it is going to blur and distort has to be there for the render engine to calculate it).

The closest thing I can think of is just to make the glass transparent, and the client is going to have to have some way to take their background images and process them to look like they are seen through frosted glass (some combination of noise, blurring, overlaying a layer that adjusts things to be a bit more pale and milky, etc. in Photoshop or similar)

Title: Re: frosted glass and alpha
Post by: sprayer on 2019-08-26, 17:33:14

This transparency effect is refraction of your background so you can't render it without background. But you can make it in photoshop for client. Render without effect with alpha and with reflection element if you need, in phtooshop insert background, turn it into smart layer and add blur filter and give it to client, he will open smart layer and replace background image.

Title: Re: frosted glass and alpha
Post by: SHORT CUTS on 2019-08-27, 11:17:56

Thanks for the fast and helpful replys, makes sense. I will go the photoshop way and prepare it in there.