I am working on a model. I used the short cut of modeling half of it and then duplication with symmetry to get the other half. It worked very well, but I deleted one of the halves to further work on it then I duplicated it again and welded both halves together, but this time some of my polygons got there normals kind of messed up, easy enough, select the offending polygons and revers there normals. Well it dose fix the problem, but when I close the file and reopen it, it's back to the same problem. Have I stumbled on to a vertex modeling bug or am I missing something else? Any help will be appreciated greatly.

Familiar experiece, unfortunately. Carrara deals with normals on an entire polymesh at a time. So if one spot is reversed, attempts to fix it will warp everything else. I have two strategies for dealing with them. First, I use the "detach polygons" command frequently. I've found Carrara can also do nasty things, included lock-ups and crashes, if you do certain manipulations on a selection that happens to include a stray poly from elsewhere. "detach polygons" tends to clear that up. The other is avoiding n-gons. I am not entirely sure Carrara has problems with them, but I seem to have reversed normals less often on models that include only quads or tris. I'd suggest you get out of Carrara on this one; export the model, maybe run it through UVmapper and resave it, then re-import to a fresh file. Sometimes Carrara just gets a funny idea about a mesh and this is the sure way of cleaning that memory. That said, I wish the reversed normals were more obvious (like the arrow display of several other applications, perhaps?) Sometimes I don't notice them until I've imported into Poser.

Excuse my profound ignorance, but what exactly is a n-gon? Perhaps it's a polygon with more than four points? I will try your suggestion. What bothers me is that it was working good at first and this recently started happening. I can fix the normals, it dose smooth out, but the problem comes back if I close the file. I try exporting it as a Weave Front file and reimporting it. My polygon count went through the roof. But I will try other things. I thought that maybe I was doing something wrong. Thanks for your help.

Your poly count CHANGED? Sounds like part of the model isn't a vertex object at all. Either that, or you are working with subdivision surfaces; those automatically "collapse" when you export an object. N-gons are polygons with more than four sides. Some applications (like Poser) really go nuts when they see these. You can get away with n-gons for a while when you are using Carrara's subdivision surfaces, but it does not always triangulate them properly when you "collapse" down to simple geometry (aka, make it no longer a dynamic subdivision but now a mesh with a higher poly count). I've been doing the same mirroring you describe, deleting, duplicating, etc. (Also discovered that duplicating with symmetry in the Assembly room is a great way to work with symmetry in the vertex modeller). In only a few cases did I have reversed normals, and as long as I was careful to fix them before welding the halves, I was okay.

You helped me, I used the detach polygons command and that did it. It fixed it. What exactly dose that command do? Thanks for the tip.
I don't use Poser much. I have been contemplating on getting it, but I don't like it's results to much. It almost always looks a bit fake, all though I have seen some pretty good stuff with it. It just seems like it takes a lot to get something reasonably good from it.
Now if I understand you correctly, you duplicate with symmetry on the Assembly room? Don't you end up with two individual meshes, do you then use a boolean to "weald" them?
You are also correct, I am using dynamic subdivision since I feel more control with less complexity. Thanks for imparting your knowledge! I have finally boned my model. (Now that didn't sound right), and I am ready to do some animation. I can't thank you enough. It is very frustrating to be putting hours on to something only to not get the desired result, but I am back on track. Thanks to you.

Message edited on: 07/15/2005 11:48

That's pretty close. I duplicate with symmetry in the Assembly room, then go back to the vertex room and pull the preview window open as far as I can. Then I can work on a half-object while having a preview of the whole. When I'm done, I duplicate and weld in the vertex room and throw away the other duplicate. I just started doing this on a recent project and I like how it works very much. "Detach polygons" is used to make a seperate, non-contiguous mesh out of a selection. Say, if you modeled a can, detached the "lid" polys, then detailed them to make a seperate lid for a now open can. I stumbled upon this command a long time ago as a way to clean up the strays that Carrara still seems to create from time to time. I am convinvinced that the majority of the vertex room problems can be traced to Carrara trying to influence some random vertex somewhere else, or a phantom vertex you deleted but it still remembers. "Detach Polygons" cleans up the selection to just what you, well, selected.

Cool clever solution for modeling with symmetry. Why didn't I think of that? Thanks again, this project will be completed very well thanks to your help.