View Full Version : Ray-traced shadows showing through the outside of an object...

06-28-2005, 03:19 PM
I've been working on a spaceship, and I'm having some issues with ray-traced shadows showing through the outside skin of the ship unless I switch all the textures to double-sided.

I've included one example, where shadows are being cast on the outside-front of the ship. There is only one light in the scene, which is behind and above the ship. I rendered this with radiosity; the light inside the cockpit is a luminous surface on the ceiling. But even without radiosity on, I got the errant shadows.

This issue even occurs on the wings, where the shadow from the wing(s) was being cast through the vertical stabilizer on the outside. This one surprised me because the wings are actually one solid object, and I spent all night looking for leaks to no avail! I even froze the sub-d's, which also made no difference (except to greatly increase render times).

Is this a known issue, and you just have to always set surfaces to double-sided? Or is there something else at work?

06-29-2005, 01:45 AM
mmmm tough one - are you sure you don't have some translucency on, or maybe a shader? What happens if you turn raytracing off, is it brighter or darker?

06-29-2005, 10:13 PM
I am an idiot! Of course I had translucency on. I apparently slipped when I was adjusting reflections and kicked it up to 5%-- just enough to cause this really irritating side-effect. THANKS VERY MUCH!!!

06-29-2005, 10:31 PM
Don't worry about it, how do you think I was able to guess? I tore my hair out for a 1/2 hour with the same problem. :p