Live2D Rigging Basics

October 28, 2020
Daniel Chen

This guide will teach you about the basics of rigging a model in Live2D. It starts off with a .psd file consisting of the different parts of an avatar. At the end, you’ll have a minimal Live2D model that can be tested with software like FaceRig or PrPrLive.

What is rigging?

When Vtubing, apps such as FaceRig are used with a webcam to determine the streamer’s facial orientation and expression. Motions such as blinking, speaking, and tilting the head are detected and a corresponding animation is applied to the Vtuber’s avatar. Rigging is the process of defining these different animations. Prior to rigging, the model is just a static collection of parts, such as eyelids, ears, hair strands, lips, etc.

How does rigging work?

Live2D is the most popular software for rigging 2D avatars, so we will be using that. In Live2D, there are many different parameters that correspond to different movements. For example, Mouth Open is a parameter that varies from 0.0 to 1.0, with 0.0 being completely closed and 1.0 being completely open.

For each parameter, you can link different body parts that will be affected by it. For example, Mouth Open can be connected to the upper and lower lips. Then, we will define what the avatar looks like when the mouth is open (MouthOpen = 1.0) and the mouth is closed (Mouth Open = 0.0).

These specific values of a parameter where the exact configuration of the avatar is defined are called keyforms. When the parameter value is somewhere between two values, the Live2D software will automatically fill in the blanks.

That’s the gist of rigging in Live2D. For the tutorial, we will go through some concrete examples of how this is done. I will be using Mark-Kun, which is a free model provided by Live2D.

The original model has all the part names in Japanese (source). I’ve provided a version with the names in English if you want to follow along.

Download: mark-kun-en.psd

Importing and navigation

To demonstrate keyforms and basic movement (translation), let’s hook up some eyelids.

Import

First, import the Mark Kun .psd by dragging the file into the Live2D window.

You’ll be able to see all the different parts that make up the avatar. They are grouped into folders on the left, which are an arbitrary way of organizing it for your convenience.

Different parts can be selected through the menu on the left. You’ll see the coresponding part get selected on the right. The eye icon can be used to temporarily hide/show a part.

Parts can also be directly selected and moved on the canvas

Keyforms and movement

Find the parameter

Take a moment to orient yourself and find the parameters. We’ll work on the EyeL Open parameter. In the video below, you’ll see that sliding the parameter does nothing since it is not connected to any parts.

Adding a keyform

To fix this, we’ll now select the upper and lower eyelid, then press the button for adding two keyforms to this parameter. Use the shift key to select multiple parts. This adds one keyform at EyeL Open = 0.0 and another at EyeL Open = 1.0. You may also know of a keyform as a “keyframe”.

Notice below that pressing the keyform on the parameter slider will select the linked parts on the canvas, the two eyelids.

Specifying a keyform

The pose specified for both keyforms is currently the same. It’s the same pose as when the image was imported: eyes closed. We’ll manually specify the eye open pose at EyeL Open = 1.0

Test it out

That’s it! Now try opening and closing the eyes with the slider. Notice how it automatically interpolates between the keyforms. The same process can be applied to the right eye.

At this point, you could even import this into PrPrLive and be able to try out opening and closing your left eye. For a guide on how to use PrPrLive, click here

What’s next?

Defining the avatar’s pose at the keyforms for different parameters represent the core concept of how to rig your Live2D avatar. Besides translation, there are many different techniques for improving the quality of your animation.

You may have noticed that the eyelids are too large and would look better if constrained to the eyeball. I’ll show you how to do that in the next tutorial.


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