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Please, need help with Blend Shape issue

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    Please, need help with Blend Shape issue

    I'm writing because there has appeared a question which I've been trying to solve for a rather long time and still can't find the solution.
    As I have changed my mesh a little bit in order to fix UV and fingers ( I was asked to do that so I could publish my model), I had to rebind skin, copying weights and I had to remake blendshapes (morph targets) because of the clean history of the mesh after the new skinning.
    After I made blendshapes for Upper Arms, I proceeded to fix twisting of the wrist, and here I have got stuck.
    Usually, when I create a new "Pose Interpolator" I select a joint and then create new pose with active red button and values of weights = 1.0
    However, values on the wrist are always less or more than 1.0. That causes terrible deformation while rotating joint to it's starting point after sculpting.
    I have tried to find information on many sites, including Autodesk, tried changing the order of mesh inputs, targets (like object space, target space,transform space) and blendshape options (pre-,post- and after deformation).
    Tried setting keys on deformers, so that the wrist could rotate gradually changing it's thickness, and tried changing skin weights and manipulating with Blend Shape weights, but if I paint all it with black(0) and then rotate to the start pose, obviously my blendshape doesn't work anymore.

    That's why I would like to ask you, if there someone who knows Maya and could help me to solve this problem or I should somehow fix wrists in UE4?



    Attached Files

    #2
    As per your current problem, maybe this post is describing the same issue with fix https://forums.autodesk.com/t5/maya-.../5450652#M5912



    I can't really speak on anything maya specific since I haven't used it in years, so I'll keep this generic.

    I dodge making blendshapes for limb twisting by adding a second bone to do the twisting for me (and driver is easy to set up in ue4). I don't cut the limb bone in half, instead I duplicate the bone onto itself, rename with suffix "_twist", then make the twist bone a child of the original. Twist bone for the upper arm carries the weights of the shoulder and is driven by inverse of original bones twist rotation. Twist bone for forearm carries weights for the wrist and is driven by the twist rotation of the hand bone.

    The reason for building bones this way is you can theoretically get a perfect weight gradient running the length of the limb. Looks really clean on it's own, as it gets rid of weird deforms of simple forearm-to-hand joints. But it would actually be near perfect to then reintroduce a morph target to counter the remaining twisting volume deformation.
    Last edited by NotSoAccurateNo1; 02-03-2020, 04:50 PM.

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      #3
      Originally posted by NotSoAccurateNo1 View Post
      As per your current problem, maybe this post is describing the same issue with fix https://forums.autodesk.com/t5/maya-.../5450652#M5912



      I can't really speak on anything maya specific since I haven't used it in years, so I'll keep this generic.

      I dodge making blendshapes for limb twisting by adding a second bone to do the twisting for me (and driver is easy to set up in ue4). I don't cut the limb bone in half, instead I duplicate the bone onto itself, rename with suffix "_twist", then make the twist bone a child of the original. Twist bone for the upper arm carries the weights of the shoulder and is driven by inverse of original bones twist rotation. Twist bone for forearm carries weights for the wrist and is driven by the twist rotation of the hand bone.

      The reason for building bones this way is you can theoretically get a perfect weight gradient running the length of the limb. Looks really clean on it's own, as it gets rid of weird deforms of simple forearm-to-hand joints. But it would actually be near perfect to then reintroduce a morph target to counter the remaining twisting volume deformation.
      After reading both of advice, I've tried to check if there possible somehow to fix that problem with skin weights. However, the difference wasn't noticeable so much. Then I tried again to deep inside blendshapes, as I don't really want to remake my skeleton because of time consuming. When I created another one deformer "parallel", which I didn't try yet, something happened - the value of weights in "pose editor" equaled "1" and the hope appeared, that the problem has gone. Especially, when I rotated the joint to the start point and it looked great. BUT when I tried to import my skeleton mesh in UE4, there have imported all body parts, like hair, eyes, teeth except the body. I suppose that happened because there is something wrong with history of mesh and I have had already same problem and solved it by clearing all history by myself.

      The problem with wrist didn't solve yet and I will be really appreciated if somebody can give me some idea

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