Booleans

Support Basics & Interface
1

Okay, so I know the very basics, and I’ve been using them successfully, but sometimes the booleans leave behind black “noise” on my objects when I render them. It’s not every time, but only in certain circumstances. I’ve been told that noise is the result of flipped normals or overlapping faces.

(I have yet to deduce the pattern, I just know that it refuses to do certain things most of the time and others all of the time.)

Help!

2

can you load up a sample file so we can look at it and try to help here ?

salutations

3

I don’t know how to upload a .blend file. Could you explain how to do that if that’s what you wanted.

Anway, a slightly out of date before…

http://img168.imageshack.us/img168/2531/destroyerh.jpg

And here’s what it looks like after…http://img695.imageshack.us/img695/7366/destroyerkx.jpg

4

I’ve noticed that for some reason when using booleans in Blender 2.4x the operation would created duplicate geometry. I think what you have going on there are objects occupying the same space which causes them to render black or with “stripes”.

5

I noticed that too, but even after I delete the “old” mesh, the problem remains. I don’t know what to do.

6

it looks like the normals are reversed… try ‘inverting normals’

7

I found a work-around. This question is now purely a learning experience. Though I will note that I couldn’t fix it via ctrl-n or ctrl-shift-n. Any ideas?

8

What usually causes ctrl-n to fail, is internall faces, breaking the calc of whats inside and out side.
It may be the booleen operation, created some of these, or they have been there from your earlier modeling. Try tracking these down and remove them, then retry ctrl-n.
On some very detailed meshes these can be very hard to find, so you can also shift click all the black faces, and flip the normals on the W menu.
I think the others mention this, but in renders you somtimes see this with co-planner faces. Remove doubles somtimes
works if both planes share the same verts. If they dont, click and drag to see whats behind the selected face, then let it snap back. You can then decide which one to remove.

9

Here’s what I’d suggest…

  • As a general rule-of-thumb, periodically “recalculate normals outside.”
  • Use boolean modifiers.

(If #2 is “I’m already doing that,” kindly disregard.)

10

At the risk of sounding impertinent, why #2?

Btw, I appreciate the time that went into all of these responses. Before I forget, THANK YOU ALL!