View Full Version : No alpha in glass object???

04-17-2006, 09:54 AM
Trying to render a simple glass box as a 32-bit image (with alpha obviously) which I then want to bring into Photoshop to composite over a background image. Used preset of Outside Glass and rendered it, but its alpha channel is pure white, no gray at all! When I composite in PS, there's definitely nothing transparent about the object.

I've been using LW for 8+ years and have never had this problem. My render settings are correct (checked them 4 times), I definitely am using transparency (again, the glass outside preset). I must have hit something that has messed this up.

Any ideas?

04-17-2006, 10:10 AM
Make sure you are not raytracing the glass...
Basically turn off raytrace transparencies in the render settings, and make sure the index of refraction of the glass surface is 1.0... then it should work.

If the glass is raytraced tha alpha will always be white.


04-17-2006, 10:27 PM
They fixed that n 8.5... sorta. In LW6.5 you'd get an alpha of the refracted rays, then in 7 it became solid white. Now in 8.5 it seems to be an even value equivalent to your transparency value. Can't get it to show the refracted values unfortunately.