Tutorial: Animation retargeting in Maya LT - part 1

Aug 27, 2019 at 02:00 pm by nemirc

Maya or Maya LT are very good tools for character animation. However, if you’ve used Maya in the past, and are now moving to Maya LT, you will see some things are different.

For my projects, I use a lot of pre-made character animations, since using those, and modifying them, is a lot easier and faster than animating everything from scratch (I still make animations from scratch when there’s no pre-made animations I can use as a starting point). When I use pre-made animations, I usually follow this workflow: import the pre-made animation into Maya LT and prepare it for retargeting, retarget the animation onto an HIK rig, adjust the animation position (if needed), and modify the animation (if needed) to fit my needs.

Pre-made animations can come from different sources. For example, this is an animation I got from Mixamo:

In Maya LT, you can use the HumanIK module to animate your characters. HumanIK allows you to set up your bones and automatically create a rig that makes animating characters very easy thanks to its toolset. However, one of the most important things is that the rig actually keeps track of bone labels, which makes it very easy to retarget animations. What this means is that HIK knows exactly which bone is an arm bone, or a leg bone, and so on. This means that retargeting can occur by “copying” an animation from one character to another.

Also, as a personal preference, I like to add an extra keyframe at the beginning of the animation, and set the character in a base T pose. I can’t tell you this is something you should or should not do, because I get mixed results from this. Sometimes, animations work better when I do this, and sometimes I’ve found no need to do it.

The next step is to assign the bones of this imported animation to a character definition (check your Maya documentation for more on this), so HIK knows what bone belongs to what body part.

After creating the character definition, save and close the scene, and open your scene with your HIK-ready character. If you don’t have it yet, then simply create it. If you’re like me, and are using Mixamo, you can get an auto-rigged version of your character from the Mixamo website, so you can import that one into Maya for HIK setup.

Save your scene as a different scene (to avoid accidentally overwriting your HIK rig scene), and then import the first file (the one with the pre-made animation). HumanIK allows you to select different “sources” for your HIK character animation. If, in that drop down, you select the character you just imported, your HIK rig will use the pre-made animation to drive its movement.

The following video shows the result. As you see, one of them is floating above the other a little bit. We can take care of that later.

Keep in mind that, right now, your HIK character still doesn’t have the animation applied. It’s simply “mirroring” or “copying” it from the imported file. You can bake the animation onto your HIK character’s bones or control rig. I usually like to bake it onto my HIK control rig so I can freely adjust and modify using said rig. You can still modify the animation if you bake it to the bones, but modifying means you have to manually transform every bone, since there’s no longer a rig to animate with.

If the animation is exactly what you wanted, then you are good to go. You can then bake the modified animation onto your HIK character’s bones, and then export it to Unity. However, before you do that, remember to delete any useless objects. For example, before you export your animation to Unity, you will need to delete the character that had the pre-made animation. If you don’t do it, you will end up exporting two characters instead of one.

Sometimes, pre-made animations are not exactly what you are looking for. For this reason, on part two I will discuss how I modify animations to fit my needs.

Sections: Tips + Tutorials

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