Animator's Guide to Importing Into Unreal Engine
Unreal engine is a fantastic rendering tool, it's fast, it looks good, and it's a great tool for animators. The Unreal Engine Marketplace offers many free assets for people to use, such as, models, environments, VFX, and more. Unreal is a bit tricky to figure out, especially, for new users; there's just so much in it that it can feel overwhelming. For now, I'm going to show you how to import your animations into unreal as I personally feel like that's the hardest part of it all, but I will provided additional resources that may help or if you just want to learn more.
This guide best suits people who are interested in creating cinematics or just want to use Unreal as a rendering tool.
There are two ways to export and import your animations; the first is using FBX and the second uses alembic cache. FBX is great for rigs that are game ready, while, alembic cache allows any rig, game ready or not, to enter into Unreal. I'm gonna start with the FBX method.
Exporting with FBX
Game rigs typically have a root joint below the character's pelvis, but some like the Space Pirate and Rathalos rig don't. It's pretty easy to tell what a game rig looks like as the bind joints live outside of the driver joints. Below are some examples of game ready rigs, as well as, links to find them.
Nora Rig by Keil Figgins
Space Pirate Rig by Tre Vital
Rathalos Rig by Joe Toole
Exporting game rigs is fairly simple and straight forward. Just open the rig of your choice, select the bind joints, then the model. From there hit export selection and make sure animation is checked off in the options menu. You only need to export the model and joints together.
Exporting the rig
Exporting animation has more steps but it's just as easy. If you referenced the rig into your scene (which you should always do), just make sure to import the the rig and delete the name in the namespace editor (I think this part is for game devs or tech animators to connect and blend animations together. I kinda skip this step as it works fine for my personal animations). The one thing you have to do is bake the animation onto the skeleton, since, you want to import your animation into a game engine. After that, just select the root joint and hit export selection. You don't have to worry about selecting the rest of the joints as it will take everything in it's hierarchy.
Exporting Camera animation
Exporting with Alembic Cache
Exporting with alembic is a bit trickier since the way you export it will depend on the rig you are using, I can't show you every scenario since every rig is unique, each, with their own challenges; I'll just show you the basics and a few things to look out for when exporting.
There are 3 options you should click before exporting the animation, they are, World Space, UV Write, and Write UV Sets. UV Write and Write UV sets are self explanatory, they export the UV's with the model. World Space just records the model's positioning in space.
Apollo rig by Ramon Arango
Recently, I had a rig that gave me trouble in Unreal, only half the textures were displaying. It took me a while, but I eventually realized the other half of the textures were in a separate UV's tile. To solve this, I broke apart the mesh in two chunks and exported those chunks separately. The hard way of exporting the mesh separately is by manually selecting the correct faces and deleting them. The easier method is to select the faces via UV's, delete them, then export the rest of the model. Rinse and repeat with the other half.
Then, I imported both the meshes and combined them in Unreal Engine. The animation plays like nothing ever happened.
Like I said, each rig comes with their unique challenges, but it's not that hard to solve the problem; it just takes a bit of patience.
Exporting the Animation in two
Liz rig by BuiltbyCollosus
Importing into Unreal
The process between importing an FBX or Alembic is similar so there is not much to memorize. I'll start with importing the FBX.
Before you can import your animation into Unreal, you'll first have to import the rig. After that, you can import as many animations you wish and connect it to the rig.
You don't have to worry about settings, default work just fine.
Unreal FBX Import
Importing Alembic Cache
Unlike importing with FBX, alembic requires you to do a few changes in the settings before it can work. Make sure to select skeletal under the alembic tab. Geometric cache works sometimes and it will occasionally cause my animations to skip or double up on the same frame, making my animation look choppy. Part of my discovery came from UnrealVirtual-Production-white-paper; I recommend giving that a read if you want a better understanding of the pipeline.
Unreal Alembic Import
Importing the split mesh animation
Getting Your Animation to Play in Unreal / Importing Camera
When it comes to playing your animation in unreal, the process is the same for Alembic and FBX; it's quick and easy. One thing to note is always zero out the mesh, that way your animation will play in the same place you animated it.
Playing Animation using the Sequencer
For the sake of this guide, I wanted to keep things simple, but if you're interested in learning more about using sequencer, here is a playlist by Epic that goes in depth on using sequencer. UE4 Cinematics With Sequencer. While you're at it here is another playlist that will teach you a bunch of tips and tricks for Unreal Engine
Importing the Camera
The process for importing textures is the same for Alembic and FBX. Not all rigs will require you to create flat colors for their materials; some will just need the texture for its base color.
Below, I recreated my scene for the animation I've been using in this guide.