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Thread: Question about modeling symmetric objects & using the mirror tool

  1. #1
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    Question about modeling symmetric objects & using the mirror tool

    Hello everybody,

    I'm using LW 11.6.3 and I started a new project using the box modeling method, however I noticed something that bothers me because I never see this problem in other 3d applications.

    The workflow I'm using is this: I made a box, add some edges here and there and then, align a series of points to the zero on the x axis, in order to delete half of the model just to make things easier. Then later using the mirror tool, so I can complete the other half of the model.

    But the problem arises when I delete the unwanted half, because somehow, lightwave adds a polygon in the open area which at first, I couldn't notice. Then later when I use the mirror tool, everything seems to work ok, I keep the merge points option checkbox on and then hit tab to see the final result. But what happens is that I get a dialog box saying that "Only faces with at least 3 vertices can be converted to Catmull-Clark patches".

    I didn't knew what was the problem, until I checked the statistics windows in order to see any anomaly and that's when I found the issue.
    I've tried to replicate the problem with a subdivided box and get the same result, there's always a polygon when I delete one half... so my question is: Is this a normal behavior? As I said, I never seen this issue in some other 3d apps. Also, is there any other way to work with symmetric objects without having to do this "extra step"?
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  2. #2
    it's a manhole cover ↓ JoePoe's Avatar
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    No, not normal behavior.
    If it's happening consistently I would guess there already is an accidental extra step in your process which is causing this... Other than that maybe your configs (but I doubt it).
    Can't tell much from the image. Where is the extra poly? By the wording in the warning, the offending geometry is a one or two point poly, yes?
    Are you hitting p with a single or couple points selected at any time?
    If you see the merge points option, then you are using the Mirror tool. Does it still happen if you use the Mirror X tool?

    Maybe if you post an lwo with each step of your process in a new layer we can pin it down.
    (name the layer with the action you did)

    Also.... yes, you can work in Symmetry mode..... activate with button at bottom of work area.
    Last edited by JoePoe; 01-18-2015 at 09:16 AM.
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  3. #3
    Registered User Slartibartfast's Avatar
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    Are you deleting just the points? In that case, first switch to polygon mode and then delete the unwanted half!

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    Joe, the extra poly is the one depicted in the image in yellow color, it's not an edge selection but a polygon left by deleting one half of the mesh. However, reading Slartibartfast answer, I think this strange behavior is normal because indeed I'm deleting points. I've tried the same procedure as before but this time with polygon selection and voila, there's no polygon left when I use the Mirror Tool so I can hit tab to smooth the mesh and there's no warning this time.

    I think is weird that you cannot delete points without getting strange geometry, but well... I need to consider this from now and then.

    Thank you ver much guys.

  5. #5
    Quantum Mechanic danielkaiser's Avatar
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    Never mind.
    Daniel Kaiser

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  6. #6
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    Quote Originally Posted by spieluhr_x View Post
    I think is weird that you cannot delete points without getting strange geometry, but well... I need to consider this from now and then.
    No, it's not strange.

    Make quad with Pen tool, or Box tool,
    select two points,
    press delete.
    What is left?
    2 point polygon..
    You're doing the same, but 2 point polygon is overlapping with 2nd side of mirror = disappearing.

  7. #7
    it's a manhole cover ↓ JoePoe's Avatar
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    Very interesting. I'd don't think I've ever tried to symmetrize that way.
    I do use that technique, however, to make two point poly chains. So it makes complete sense.
    So you had a whole bunch of extra polys. Other 3D apps allow that?


    Also, a quick amendment to my symmetry statement above....The answer is still yes, BUT, Some tools and plugs may not cooperate.
    Last edited by JoePoe; 01-19-2015 at 11:13 AM.
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    Quote Originally Posted by Sensei View Post
    No, it's not strange.

    Make quad with Pen tool, or Box tool,
    select two points,
    press delete.
    What is left?
    2 point polygon..
    You're doing the same, but 2 point polygon is overlapping with 2nd side of mirror = disappearing.
    Uhmm, never thought of it, but now it think it makes sense.
    It is just that I'm used to a different behaviour from Max, where you can delete points (i.e half of the mesh to work just with one half, then later add a symmetry to complete the model) but usually there's no extra geometry left.

    But thank you so much for clarifying this.

    By the way, how did you guys work with symmetric objects? I always thought the easiest way is to work with just a half.

  9. #9
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    Quote Originally Posted by spieluhr_x View Post
    By the way, how did you guys work with symmetric objects? I always thought the easiest way is to work with just a half.
    Take a look at Virtual Mirror
    http://www2.trueart.pl/?URIType=Dire.../VirtualMirror
    You will be able to edit one half of mesh, while seeing 2nd mirrored side but not being able to edit it. All in real-time.
    Video tutorial made by William Vaughan will explain it better ftp://ftp.newtek.com/pub/LightWave/T...dz/Vmirror.mov

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  11. #11
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    from the same developer as above - apparently works after maps, morphs have been added. (haven't tried it yet)

    http://artstorm.net/plugins/fix-symmetry/

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