Skinning a Character in 3ds Max - Part 7 - Shoulders
In this tutorial, you adjust the skinning of the shoulder area. This is arguably the hardest area to adjust and you will find yourself spending a lot of time fine-tuning it. The reason is that vertices in that area are likely to be affected by more than two bones and therefore require a little more attention. However, the principles learned still apply and you simply need to be patient adjusting the solution.
- Recorded in: 3ds Max 2013
- This tutorial is intended for use with 3ds Max version 2013 or higher.
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We come to what is arguably the hardest joint to skin properly, the shoulder joint.
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The reason is that this joint is articulated in many different ways.
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The vertices in that area often respond to three or even four bones simultaneously.
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The key is identifying those bones and applying the proper weights.
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There are no strict rules or strict values to be used. Skinning, as you have learned so far is mostly visual, and a bit instinctive.
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First adjust the animation length to focus on the area of interest.
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Most of the shoulder animation is taking place between frames 880 and 1160.
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Obviously the skinning at this point isn't working too well but you're about to change that.
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First make sure you are in the Front view.
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Press F3 to switch to wireframe mode, and take a look at the animation.
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The shoulder rotates down between frames 880 and 900.
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However, consider how it rotates up between frames 920 and 940.
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Much of the work is done by the clavicle, although the shoulder bone does rotate a bit also.
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In fact, there is even a slight twist of the shoulder bone, the higher it rotates.
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Try it out: lift your hand above your head and feel the slight twist of the shoulder bone.
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This is important to get the shoulder vertices to work properly.
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If you just rotate the shoulder and leave the clavicle untouched, this would result in bad joint animation.
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Before starting the skinning adjustments, notice the FK and IK bone chains.
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These won't be used for skinning as discussed earlier, so you might as well hide them from view at this time if you haven't done so already.
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The FK/IK branches for the left arm are easy to select around frame 900.
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The ones for the character's right arm are a bit harder to select in the viewport.
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Press H and select them from a list, or zoom in and double-click the respective shoulder bones to select them in the viewport.
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Hide the selection.
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Go back to a shaded viewport (F3), select the mesh and enter Edit Envelopes mode.
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Let's analyze the situation a little bit:
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At this time, most of the torso vertices are not affected by any of the clavicle or shoulder bones.
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This is expected as you set up the upper torso vertices to follow the upper spine bones earlier.
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As far as blocking out vertices, you may want to make a few last minute adjustments before proceeding.
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In some situations as is the case here, loop selection may not work to your advantage.
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So make sure you go around the scene so that the right vertices are selected.
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Assign these vertices to follow the shoulder Roll bone 100%.
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Block out any other "rebel" vertices in that area.
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Let's explore the clavicle area.
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All these vertices need to be somewhat affected by the clavicle bone, although by different amounts.
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The vertices further out need higher percentages than the ones closer to the middle line.
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Start by selecting the vertices near the bottom end of the collar.
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Open the Weight Tool dialog. At this point, these vertices are affected only by the Spine bone.
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Select the clavicle bone and weight the vertices by a small value, such as .1 or 10%.
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Select the next few vertices in line. You will almost certainly need to adjust the back vertices in a moment.
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For now, work on the front of the character.
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Use the Weight Tool dialog or the Weighting script to assign an amount of clavicle influence on the selected vertices.
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Move on to the next few vertices in line and adjust their weighting.
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Soon enough, you will find yourself going back and forth, adjusting vertices as a group, or almost certainly individually.
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This is where the weight script tool comes in handy.
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As you test the vertices around the shoulder area, you will discover which vertex needs to react to which bone.
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You will also find that some vertices, although far from the center line, need a bit of weighting from the spine bone.
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This helps in "grounding" them a little bit.
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Keep on fine-tuning the solution, occasionally glancing at the back of the character.
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Remember this process is fairly intuitive and requires a great deal of patience.
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The more experienced you become at this and the easier it gets.
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As you go below the arm pit, there are a few vertices that need to blend with the arm bones.
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It's best to blend these with the shoulder bone, and not the shoulder roll.
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You only need for these vertices to react to the up/down motion, not so much to the shoulder twist.
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Keep on fine-tuning the solution. Again, a lot of back and forth is required to get to a result that you like.
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Notice that you're only working on one side of the character.
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When you're done, you can use Mirror Skin tools to transfer vertex weights to the other side.
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However, since you still need to adjust the rest of the arm, hand and fingers,
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you may as well completely finish with one side before mirroring the data.
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Exit Edit Envelopes mode and save your file.