Skin Wrapping in 3ds Max - Part 2 - LOD
In this tutorial, learn how to use Skin Wrap to transfer skinning data across multiple LODs (Level-of-Detail) on your original character. This is a huge time-saver as it enables you to quickly create multiple skinned instances of the same character to use in various places in your game engine.
- Recorded in: 3ds Max 2012
- This tutorial is intended for use with 3ds Max version 2012 or higher.
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Inevitably when you're developing a game, you will have to deal with LODs.
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LOD stands for Level-of-Detail. It's a process to define how complex an object is
based on its proximity to a camera.
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A character for example needs to be fairly detailed when the camera is very close.
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From a little further out, that same character will require only medium detail,
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and from a greater distance still, low detail can be used
as your eye wouldn't perceive it from that far.
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You can see the difference in poly-count between these three otherwise identical characters.
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Using Skin Wrap like in the first movie, you can transfer skinning data
from one character to another.
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Typically, a rigger would skin a low-res or a medium-res character
before skin-wrapping a high-resolution model.
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In this case however, the character that is already skinned is the more detailed one,
and you'll use Skin Wrap to skin the LODs.
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In this particular case, the "hi-res" character is only about 2,000 faces and is easy enough to skin.
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If the model were made of half a million faces, then it would have made sense
to skin a lower-res version and then transfer the weights via Skin Wrap.
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Select the Medium and Low LODs and relocate them to [0,0,0]
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Make sure both LODs are selected; you can use the Selection Set to that effect,
and apply a Skin Wrap modifier to them.
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Start with the medium LOD. Notice that the Skin Wrap modifier is instanced.
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What you do with the Medium LOD will affect the Low LOD as well.
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Make sure the Deformation is set to Face with a 0.001 Falloff
and add the Full Body character to act as a Control object.
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It is probably best to select the Full Body character from a list by pressing H.
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When the Process is complete, right-click to exit Add mode.
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If you want, you can test the skinning by selecting a Biped part and exiting Figure Mode.
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You'll find that Skin Wrap worked flawlessly.
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This was a little expected in this case, since the LODs and the original character
are really based on an identical structure.
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Go back to Figure mode when done.
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Ultimately, you would need to convert Skin Wrap to regular skin,
especially if you plan to save individual LODs as separate files.
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Because Skin Wrap was instanced, you will get an error message
if you tried to convert Skin Wrap to Skin.
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First you need to make the modifier unique for that process to work.
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Now you have the Low-LOD and the Medium-LOD independently skinned to the biped skeleton.
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But here's the problem:
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Your Art Director comes along and decides to make a change to the original character.
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The new character is to have a tiny waste and bulging biceps,
and therefore the LODs have to be adjusted accordingly.
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So, not only do you need to adjust the original mesh, but also the LODs for that mesh as well.
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This is where Skin Wrap really shines: In addition to using it to transfer skin data,
you'll use it as a modeling tool as well.
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Before you start making geometry changes, remove the newly applied Skin modifiers from the LODs.
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Obviously, these cannot be used anymore if the character's geometry has changed.
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Now select both LODs again and apply an instanced Skin Wrap modifier.
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Choose the Full Body mesh as a control object one more time.
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Make the Skin Wrap modifiers unique but do not convert them to skin just yet.
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Now let's see what happens as you start editing the main character's geometry.
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Select the Full Body character and in the Modify panel go to Editable Poly > Edge sub-object mode.
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Select a horizontal edge around the belly and choose Loop.
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Enable Soft Selection and scale the waist down a bit.
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Notice that the LODs have followed suit, courtesy of the Skin Wrap modifier.
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Skin Wrap is almost acting like a deformation tool for the geometry,
not only to transfer skin weights.
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Use the same technique to beef up the biceps or shoulder areas,
and you have a totally new character.
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This technique can be used to create variations such as Skinny/Medium/Fat versions
of the same character.
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There is however one catch to look out for.
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Select either LOD models.
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You have to be very careful how you proceed to convert the Skin Wrap modifier to skin here.
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Before moving on, choose Edit > Hold. This will enable you to come back to this point
if you encounter a problem.
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If you click on Convert to Skin now, you'd be surprised to see
that the LOD has lost the change in geometry information.
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This is due to the fact that the geometry change information is stored
into the Skin Wrap modifier, which is now turned off.
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Notice what happens when you enable or disable it.
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Make sure the Skin Wrap modifier is enabled, right-click it and choose Collapse To.
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Click Yes to dismiss the Warning message. Now the geometry change is stored
at the editable poly level.
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Repeat the procedure with the Low-LOD.
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As you can see, this LOD technique can be very useful
when you need to generate additional characters based on some geometry changes.
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In the 3rd and last movie, you'll experiment by adding additional props to an existing character.