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Very curious UV unwrap... What's going on...??

DustyShinigami
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DustyShinigami polycounter lvl 3

Hi

I have a game model I found that I'm using as reference whilst I make my own. I added a UVW Unwrap modifier in Max to the arms just to see how the unwrap was handled and came across something I've not seen before. I was hoping someone could shed some light on it. It's probably some very straightforward method that I've not encountered before. I figured the unwrap was just overlayed, but that doesn't appear to be the case. There looks to be just one UV shell for the arm and one for the fingernail, but selecting it selects both arms. Same for the nails. I even tried adding the modifier to just one arm, but the editor doesn't show the other one anywhere. o_O I've uploaded a GIF to show:


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  • Swordslayer
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    Swordslayer interpolator

    Overlaid with shared texture verts (imagine it as the overlaid verts being welded), which is why it move the other part as well. The texture verts can be shared among any number of faces, technically all faces in the mesh can be assigned a single texture vertex and it's valid mapping (though I don't think you're able to do that via the UI). If the engine supports that, it means less texture verts (and less memoty taken).

  • DustyShinigami
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    DustyShinigami polycounter lvl 3

    Huh. That's interesting. I've never heard or come across that before. How does that work exactly? I'm a bit confused. How would you typically go about doing that?

  • poopipe
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    poopipe godlike master sticky

    its usually caused by export to obj or some other simple/optimised format

  • pior
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    pior grand marshal polycounter

    Yeah, don't overthink it. The only thing that matters is the overall strategy (both arms sharing the texture space ... and, these beutifully straight japanese-style UVs !). From there the model has been processed at least 3 times (once or two times to export it to the engine, another time to rip it out, and one last time for you to import it) hence one can expect a lot of weird things happening.

    Also if I am not mistaken, some 3d software does allow one to merge UV verts the same way one would merge regular verts.

  • DustyShinigami
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    DustyShinigami polycounter lvl 3

    I see. So this kind of things happens automatically on export/import? Can't say I've noticed it with any of my meshes though.

    Yeah, I've seen that method used before with the straight UVs. So the Japanese were the ones to start packing them like that? Is that just done using the Straighten UV options?

  • pior
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    pior grand marshal polycounter

    No, it doesn't happen automatically on export/import - it may happen on export, or on import, or during mesh ripping ... in some cases. There are hundreds of possible permutations, with the one you ran into being just one of them.

    And, I have no idea if they started doing that, litterally, all of them. Who could know ? I just know that I've noticed this often on rips from japanese titles, and much less in the case of western games. It's a cool throwback to a time when more people (including here) were doing it that way to maximize texture space and get clean pixel-perfect textures. But as model density gets higher it becomes a little more delicate to do, hence many just rely on an automatic pelt unwrap instead.

    (Please don't take speculative remarks as some kind of absolute truth ...)

  • Eric Chadwick

    Bbbut.. you're a godlike master sticky

  • DustyShinigami
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    DustyShinigami polycounter lvl 3

    Huh? What do you mean by godlike master sticky...?

    I had no idea they were speculative remarks. It's difficult to know when it's via text.

  • Eric Chadwick
  • DustyShinigami
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    DustyShinigami polycounter lvl 3

    Ohhh, I see what you mean. :p

  • pior
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    pior grand marshal polycounter

    LMAO :D

    Anyways ! Good luck with the model study - model rips are always fun to look at, and very educative for sure.

    As for speculative stuff - it's just like people calling a certain kind of bevel "Korean bevel", that doesn't litterally mean that every Korean artist makes their models that way, but there's often a grain of truth to these things.

    French fries.

    English breakfast.

    And so on.

    But I'd go as far as saying that there is definitely a certain Japanese style of modeling, with models being often put in a very clean and simple T-pose for instance (as opposed to a convoluted "relaxed" pose that doesn't have that many advantages at the end of the day). Or as said, the kind of very clean UVs used on the hands here that I remember seing in old model rips from PS2-era FF games.

  • DustyShinigami
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    DustyShinigami polycounter lvl 3

    I guess part of it is due to me having Asperger's, so I do tend to take things literally. It's easily done when it's via text. 😅

    When you say 'convoluted "relaxed" pose' do you mean the A-pose? That's the pose we've been taught to use over the T-pose. Also, those clean UVs - are they done that way by just straightening all the edges? I just seem to imagine, when manipulating the edges to make them like that, that it'll effect the distortion checkers where they'll show up red/blue in Maya.

  • pior
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    pior grand marshal polycounter

    Well, regardless ... you're kinda doing it again hehe :D

    I never stated that a A-pose in inherently bad. All I am saying is that *in some cases* it can end up being needlessly convoluted, for instance because of too many people having an input. I've witnessed enough of these discussions (sometimes being directly involved with them and sometimes just as a fly on the wall) to know that more often than not some people just assume things instead of actually knowing what they are talking about from actual, practical experience. And then it can end up in a pose that is neither good for animators/riggers because it doesn't zero out cleanly, and not great for the modelers either because it requires to work at weird angles, and/or causes models to look "uncool" during review (and while some will pretend that it doesn't matter, it actually very much does). Whereas by nature, a straight rigorous T-pose doesn't do any of that.

    Now admittedly I've mostly worked on projects involving a "relaxed A-pose" (some good, some not so good) and only 2 with a straight T-pose. But I can 100% confirm that a bad A-pose can be a huge pain in the ass. The default UE4 mannequin is a striking example of that.

    I personally quite like the compromise of arms being at 45 degrees and everything else being dead straight (including fingers) ...

  • kyaroru

    "Relaxed A-pose" sometimes ends up as a buzzword for "not a single limb is in a straight line despite looking like it" indeed.

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