Skinning a Character in 3ds Max - Part 5 - Hips

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10 min

Skinning a Character in 3ds Max - Part 5 - Hips

In this tutorial, you adjust the skinning on the hips and upper thighs areas.

  • Recorded in: 3ds Max 2013
  • This tutorial is intended for use with 3ds Max version 2013 or higher.
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It is obvious from the current animation that the hips area needs quite a bit of adjustment.

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This includes the thigh joints, buttocks and lower belly areas.

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Adjust the timeline to view the scene between frames 360 and 880 to focus on that area.

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The thigh joints (along with the shoulder joints) are among the most difficult to skin properly.

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Perhaps the term "difficult" is badly chosen here, as the process is the same as you have already learned,

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but it does take more time and effort to get this area to work to your liking.

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Don't let that scare you as the principles you have already learned still apply.

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First you start by blocking out the skinning, by selecting vertices and assigning them to their closest bone,

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and then you blend joint vertices to react to two or more bones.

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This means selecting one or more skin vertices, select a bone to affect them,

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and adjust their weights until it visually makes sense.

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With the proxy mesh selected, enter Edit Envelopes mode.

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In a side view (such as the left view), use the lasso tool to select vertices around the hips area.

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Do not go too low or too high at this point.

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In a facing view, add the vertices around the crotch area.

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Go around the back and add any vertices that should be part of the selection.

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Block out the selected vertices to follow the hips bone 100%

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Do not worry about the character's right leg at this time. You'll use Skin Mirror tools in a second.

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Obviously the belly area needs some work as well.

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Go back to the left view and select the vertices around the lower belly bone.

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Select the lower belly bone (or Spine1) and assign it a 100% influence on the selected vertices.

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Go up the spine, select the vertices around Spine2.

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Select the Spine 2 bone and assign a 100% influence to block out that area.

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You'll worry about the torso later.

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Now that you've blocked out the work, you can go in and fine-tune the weights.

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The concept is the same as what you have already learned.

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You need to select a vertex loop, and blend its values between two or more bones.

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Adjust your view again to look at the character from the front.

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If you haven't done so already, press G to disable the grid.

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Check out the left thigh joint around frame 490. It is clear that these skin loops need adjusting.

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The process should now be familiar to you. Select a loop, such as this one.

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Remember you can use the Shift+2 hotkey you defined earlier.

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If a loop is broken as is the case here, then you need to work a little harder to make the proper selection.

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Another powerful selection method is the Paint selection tool.

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With this tool you can select vertices by "painting" over them, which involves a simple click and drag.

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However, if you intend to use that tool, enable the Backface Cull Vertices option.

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This way, you're only selecting vertices in the foreground which makes the selection more predictable.

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If you don't use backface cull, you'd be selecting background vertices as well.

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Be sure to always double check your work as the BackFace Cull option is not always reliable.

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Start by assigning these vertices to follow the thigh bone by a factor of 100% if they're not already set this way.

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Now you can fine-tune them to also be affected by the hips bone.

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Make sure you are around frame 490~492 where the character is doing an extreme split.

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With the vertices still selected, select the hip bone and press Shift+1 to activate the vertex weight script.

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Click and drag to add a bit of influence from the hip bone.

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Don't overdo it just yet, you can always come back and make further adjustments later.

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You may decide that the vertices on the selected loop should have different weight values.

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Use the Alt key to remove the top vertices from the selection.

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Use the weight script again (Shift+1) to adjust the weighting a bit more.

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Keep on adding or removing vertices and adjusting their weight to get a result that you like.

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Move to the next thigh loop, this one should be easy to select using the Shift+2 hotkey.

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Again, work the weights of the vertices on that loop to be a little affected by the hips bone.

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As before, you may need to work the weights on individual vertices on that loop.

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Adjust the next loop in line moving down the thigh.

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This one needs very little weight adjustment.

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Keep in mind you will almost certainly be coming back to adjusting these vertices at some point.

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In other words, do not worry about getting it right the first time.

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Alternate between the Paint Selection tool in Backface Cull mode and the lasso tool.

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Select vertices and adjust their weights.

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Keep an eye on how the mesh is deforming and adjust the weights accordingly.

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This means you select one or more vertices, select a bone of influence, and adjust the vertex weights accordingly.

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Keep on selecting vertices and adjusting their weight until the deformation seems to behave properly.

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Do not adjust vertices on the character's middle line yet.

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This will take you some time but it is redundant work, so we'll skip the movie ahead to limit its length.

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Once you are satisfied with the deformation, you can mirror the skin data to the other leg.

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Enter Mirror Mode and use the Paste Blue to Green Verts function.

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Look closely and notice that some vertices are not exactly symmetrical.

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Decrease the Mirror Threshold value to 0.2 and try again.

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This time, the effect is perfect.

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As far as the middle line of hips vertices go, these need to be affected by three bones:

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The hip bone and the two thigh bones, especially when the thighs rotate forward and back.

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Select all the middle vertices under the belt.

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At this time, they're affected only by the hip bone.

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To ensure the vertices are equally affected by the thigh bones, you need to use the Weight tool.

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With the vertices selected, select the left thigh bone.

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Click the .25 preset button to give it a 25% influence.

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The value matters little at this point, you'll change that in a second.

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Now select the right thigh and click the .25 preset button again.

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The weights are now all over the place.

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To fix this problem, select the middle bone in the dialog and give it a 100% influence (preset button 1).

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Now select the last bone and give it a 50% influence.

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Now each thigh bone has a 50% influence on the vertices.

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Finally, select the hip bone and give it a value, such as .75.

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The weights are normalized but at least the left and right thigh bones have identical influences on the vertices.

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From this point on, you only adjust the hip bone influence on these vertices.

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This way, you ensure that the weights coming from both thigh bones remain equal.

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Save your file.

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Remember that if you make a mistake, you can always revert back to one of the files you downloaded for this tutorial.

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In the next movie, you adjust the torso.
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