VRM Avatars

This doc covers what VRMs are and how to make them.

What is a VRM Avatar?

VRM is a 3d file format that is designed to allow creators to build and use custom 3D Avatars for use in online and VTuber platforms.

Creating Avatars has certain limitations to keep in mind depending on the platform that they will be used on. WebGL, Standalone VR or Mobile eco systems have very limited resources and therefore need to have limited polygon count, material count, and texture sizes. Desktop or VTuber platforms have less limitations as they have more processing available behind them.

Creating a VRM Avatar

An avatar is generally a humanoid type character due to the very strict skeleton, or rig, that a VRM uses. That said, with a bit of creativity you can create some really interesting characters such as a slice of pizza or can of cola by applying the skeleton, or rigging, the model to only some of the bones.

Creating an Avatar model

Keep in mind the requirements of the lowest common platform so that more people can use your VRM without issue.

Things like the polycount, number of meshes, and material count affect how well your asset works in a space (depending on everything else that needs to be rendered. Polycount and more importantly texture size will play the largest part in how big the filesize is. Keeping all these things in mind during the entire process will sometimes affect what you make and how you make the avatar.

There are many ways to create a character asset. And those are looked at in depth in The Crate Series. This tutorial will focus on making your model a VRM Avatar.

Rigging the Avatar

Rigging means applying the asset to a skeleton. Once you have modelled and textured your avatar you will need to rig the avatar in order to make it move properly.

All VRMs require a bipedal skeleton, that said, how you rig your asset is completely up to you. It is possible to have a large fish be rigged to the pelvis bone for example. The animations that are applied to your VRM depends on the platform you are using it in. Testing your avatar in different eco systems is a good way to make sure you have created it well.

It is possible to use applications such as Mixamo or Accurig to speed up the rigging process significantly, or you can manually create it. These will need a different approach to setting up the VRM, and will be covered in following tutorials.

Rigging the bones may require painting the weights of the vertices. Weight Painting defines how much each vertex is applied to a bone. Thigh vertices will be 100% on the thigh bone, whereas the knee will be 50% on the thigh bone and 50% on the shin bone.

Extending the Rig

It is possible to add custom bones to the rig that can support secondary motion on your asset such as cloth, tails, ears etc. using Spring Bones.

Exporting the VRM

There are a number of ways to do create the VRM, the two most common approaches use the following :

• VRM for Blender - This is an addon for Blender, that allows you to export the asset as a VRM directly from Blender itself.

• UniVRM - This uses an addon for Unity. It has the benefit of being able to see the Spring Bones in action without having to export the VRM.

Summary

VRMs are a fantastic format to bring your online persona to life, and with the following tutorials you can create that persona yourself! Once you have your character modelled and textured you can jump forward to rigging the character.