Maya for 3D Printing - Rapid Prototyping
In this course we're going to look at something a little different, creating technically accurate 3D printed parts.
# 1 25-06-2008 , 01:37 AM
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Trouble with 'Duplicate Special'

Hello, this is my first time posting on this forum. My name is Nick, and I just recently started learning how to use Maya... about 2 months ago.

I downloaded the Personal Learning Edition of Maya 8.5, and purchased the book "Learning Autodesk Maya 8: Foundation". The book is good, but it sometimes does not explain key details like what setting to have a tool on.

Anyway, I ran into a big problem along the way through the various exercises that the book takes the student through. (Luckily, they included a disk with files for all the projects, so that if you get stuck, you can move on to the next lesson).

Here is the problem that I had: The book instructed me to model a character using polygons with the Extrude tool, then cut the model in half and duplicate a mirrored copy with the Duplicate Special command.

So I did all of that, but when it came time to model further on the figure using the Extrude tool, the model would respond strangely at places along the middle seam of the two copies. For example, when I was trying to shape the nose using extrude, pulling them out was not a problem but scaling them caused the two polygon faces to split (scale independently).

I think the reason that the two (or more) faces scale independently is because the geometry of the two halves mirror eachother. So I tried to combine the halves, close the seam between the halves, try using 'Mirror Geometry' instead of 'Duplicate Special', but I haven't found anything that works.

In the book, they don't say anything about what you need to do to the two halves after Duplicate Special. But they go on to instruct me to keep modeling the figure, and the pictures in the book show how it's to be done.

It is very frustrating! If I didn't have the files for the next lesson, I would still be stuck trying figure out how to do this!

One last thing related to two halves of geometry. The 3-D Paint tool was also adversely affected by my mirrored geometry in that the color would not go onto the place I was telling it to, then it would shoot vertically up and everywhere else around the figure.

I would greatly appreciate any hints or information about how to fix this problem, or if there's any books that may be better than the one I have now.

Thanks

- Nick

# 2 25-06-2008 , 05:35 AM
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Re: Trouble with 'Duplicate Special'

Originally posted by nleyton

....So I did all of that, but when it came time to model further on the figure using the Extrude tool, the model would respond strangely at places along the middle seam of the two copies. For example, when I was trying to shape the nose using extrude, pulling them out was not a problem but scaling them caused the two polygon faces to split (scale independently).

I think the reason that the two (or more) faces scale independently is because the geometry of the two halves mirror eachother. So I tried to combine the halves, close the seam between the halves, try using 'Mirror Geometry' instead of 'Duplicate Special', but I haven't found anything that works.....


I doubt thats the problem, I think you need to toggle on "Keep faces together", its under either your Edit Polygons or Edit Mesh menu.


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# 3 25-06-2008 , 07:33 AM
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I can see two simple solutions:

When mirroring your geometry, your vertices on the open side didn't line up perfectly, so it ended up merging some things you didn't want it to. Fix this by selecting all the edge vertices and using the scale tool to pull them into alignment, and like GecT said, for extruding make sure Polygons>Edit Mesh>Keep Faces Together is on.


Also, your problem with the 3d paint tool painting over random stuff is because of your UVs, which are points on the model which tell the texture where to be mapped to. A simple solution is by normalizing the UVs or baking them, but that's a long and complicated process, especially if your model is at all complex.


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# 4 26-06-2008 , 11:21 AM
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When you did the duplicate special did you use copy or instance as the method?

If its an instance then you only need to concentrate on the original side as the remainder will continue to duplicate the same as the original.

Also the faces extruding my have come from the way its modelled, as the axis will be set to local first so whatever way the X,Y or Z are facing that will cause the faces to extrude in that direction for that face(s), to allow you to extract in the global axis (the original X,Y,Z) then click the little blue circle after clicking extrude and the geometry will pull out in line with that axis.

Also you may find that the vertices that run along the center axis will not have been even or centered, and as mentioned above will cause issues. To get around this problem you can select all the vertices that run along the egde of the split model and the use the scale tool to get them all even (you scale in until the R,G,B box reaches the yellow center). Once this is done then change to the move tool and hold x and move it out and then back into the center axis (holding X will cause the selected vertices to lock to the grid).

Hoep this helps you out. Everyone goes through this when we start with maya, and books cant explain every little detail as the authors are under pressure on deadlines and pages and words etc...

Might I suggested the Help files as there are tutorials on there are really good and really quite basic and will shoe how to do the basics of modelling.

Enjoy


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# 5 30-06-2008 , 03:54 PM
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Thank you all for your replies, I'll try some of these tips!

# 6 02-05-2013 , 03:38 PM
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I had to dump Preferences file

Maya 2009 Mac 10.5.8 I had the above problem. All the correct settings, Keep Faces Together, etc. I created, cut, duped and still when I moved a single vertex, the entire piece would move away from center. Finally I went in and dumped my Maya Preferences file... all better. On one computer I did it with Maya closed and on another where we had the same problem I did it with Maya open. On the open one there was already an object that had been cut down to just front facing faces (think Maya Joan of Arc tutorial) and after eliminating Preferences it started to respond correctly. Yipee.

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