Two Overlapping Windows Render Black

[one25IT]

When rendering the following scene, the area, where two transparent objects (windows) overlap, renders black.

 

This happens in both cases; the two windows stay parallel to each other, the two windows are orthogonal to each other.

 

The windows measure 2cm in thickness; the material applied is Autocad standard "Clear".

 

I remember having rendered the same scene before without any issues.

 

Two windows parallel:

Two windows orthogonal:

 

Did this happen to you? Do you know of a solution?

 

PS: The file is too large to post.

[one25IT]

Copy-pasting everything into a new drawing didn't help. The problem persists.

Now the view traverses the first two windows, but the black wall appears on the third window.

Edited December 11, 2011 by one25IT
Didn't work.

[one25IT]

I can replicate the same behavior in a clean new drawing too. So it might be simply a limitation to the software.

 

The first five rectangles are all transparent of the same type, Material Global, transparency 90%. The last rectangle is of material Global, transparency 0%.

Another example.

 

Does anybody know anything?

Edited December 12, 2011 by one25IT
More information.

[one25IT]

The problem appeared after Autocad had crashed during a render.

 

In the meantime I've tried repair and re-install function from the Windows control panel without success. I also re-installed totally from scratch. But the error persists.

 

Did anybody experience anything similar?

Edited December 23, 2011 by one25IT

[one25IT]

I found my error. It was really simple in the end! The crash set ray tracing down to value 6. I didn't figure it out, since I never had touched those settings.

It drove me crazy; I am happy I puzzled it out and wanted to let you know, in case somebody encounters this problem.

Edited December 23, 2011 by one25IT