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Thread: Distortion when subdividing - best way to handle it?

  1. #1
    May the sauce be with you starbase1's Avatar
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    Distortion when subdividing - best way to handle it?

    I'm importing a rocket mesh via OBJ, it was designed to be subdivided.
    When I do a tab and freeze, I get some rather nasty texture distortion, on UV mapped images.
    See the attached before and after - the central rocket with the pink lines, just above the nozzle.

    Any suggestions on the best way to handle this - there are alot of options in terms of how to sibdivide, but no luck with what I have tried so far...

    LW 11.6
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  2. #2
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    The most important question is whether distortions are visible in render, or only in viewport.. Viewport only distortions don't matter.

    Did you open Modeler and in Vertex Maps window, tried changing Interpolation method.. ?
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  3. #3
    You probably need to go to the UV Interpolation under the UV/Texture section unto the Map tab, you can choose between...well see the picture.

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  4. #4
    May the sauce be with you starbase1's Avatar
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    Thanks for the suggestions. I started to get different results, but then relised the texure was in the wrong place in the original! So rebuilt that.

    I'm still getting some odd results though. Some that look OK in modeller but then go very weird when rendered... There's definitely some weird things on the model,and I'm not sure what. No non planars, or 2 point triangles, but again very odd results from subdividing.

    In one case 2 bands around the rocket looked like they had negative specularity, (they got darker hen nearby areas got lighter with a highlight, and in another try, the area around the base of the rocket looked normal in shaded textured preview, but was black when rendered!

    And in all cases normal before subdividing, (I'm trying nurbs and subdivide smooth).

    Any ideas on what else I can check for in the mesh?

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  5. #5
    Super Member Kryslin's Avatar
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    Are you using Catmull Clark Subd's? The UV Interpolation really only works with Lightwave's native Subpatches.
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  6. #6
    May the sauce be with you starbase1's Avatar
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    Sorry to be dumb, which one is that?

    (And I still think there's something wierd about the mesh).
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  7. #7
    May the sauce be with you starbase1's Avatar
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    OK, I think I've got something. I went in close around an area that showed odd behaviour, and there are way to many polygons in the count, at least some of which seem to be zero area. See attached.

    Is there a way to clean this up reliably / thoroughly without going over every polygon manually?
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  8. #8
    May the sauce be with you starbase1's Avatar
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    Looking closer, that' a really narrow bevel. I still don't know how to make this work cleanly as a subdiv though. Googling and exploring the interface also can't find the option to select CC...
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  9. #9
    Super Member Kryslin's Avatar
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    Down on the bottom task bar, there are 2 buttons : One reads subpatch, the other reads Catmull Clark. If your model is normal geometry (unsubdivided), you can change the subdivision type, then pressing tab will convert the normal geometry to that subdivision surface type. I wouldn't bother freezing the model, unless, of course, you absolutely need to.
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  10. #10
    Registered User squarewulf's Avatar
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    Quote Originally Posted by starbase1 View Post
    Looking closer, that' a really narrow bevel. I still don't know how to make this work cleanly as a subdiv though. Googling and exploring the interface also can't find the option to select CC...
    If you upload that object I could take a look.

  11. #11
    May the sauce be with you starbase1's Avatar
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    Quote Originally Posted by Kryslin View Post
    Down on the bottom task bar, there are 2 buttons : One reads subpatch, the other reads Catmull Clark. If your model is normal geometry (unsubdivided), you can change the subdivision type, then pressing tab will convert the normal geometry to that subdivision surface type. I wouldn't bother freezing the model, unless, of course, you absolutely need to.
    Ah, I was looking in LW options and subdivide options! (Seemed reasonable to me!).
    Thanks for the pointer.

    - - - Updated - - -

    Thanks - but it's a paid for one, so not allowed to.
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  12. #12
    May the sauce be with you starbase1's Avatar
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    New version received from Turbo Squid. Currently working through it, thanks to all for the help.
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  13. #13
    May the sauce be with you starbase1's Avatar
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    OK, new version much better, all maps included and attached.

    I also found the major source of error, that every bump map had also been assigned as a vertex normal map, and was not even a normal map, resulting in weird surfacing artefacts.

    I've had some great stuff from Turbo Squid, but if it's not in the native format, what you get is pretty random. And has clearly never even been loaded to check all required files are there.
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