THE FACE RIG PROBLEM

As mentioned in my Simulation Research section, my initial foray into Unreal Engine was not without difficulty. I assumed, that getting a rig into Unreal Engine would be as simple as exporting as an FBX and importing it into Unreal Engine. Unfortunately for me, my choice in Rig would make it so that things were not so simple...

diagnosis

Exporting the game ready version, did allow me to successfully import the rig into Unreal Engine however I was now faced with a difficult problem. As I had discovered in my Rig Research, the game ready version of my Sylvanas rig did not come equipped with a face rig. At the time, this didn't seem like it would be an issue, as I assumed I could just use the regular version instead. However my assumptions on what a 'Game Ready' rig was, lead me to an incorrect conclusion. I believed that since I was using Unreal Engine as a rendering tool and not for making games, the optimizations of a game ready rig would be irrelevant to me, and I could simply use the main rig. This was my thinking during the original research phase, however I now found myself in a position where this wouldn't be the case.

As it turns out, Game Ready rigs have nothing to do with polycount optimisations, and are more focused on joint hierarchy's and stripping away any Maya centric features. Unreal Engine only supports a single joint chain (which some rigs don't have) and Game Ready rigs are constructed with appropriate joint hierarchy's. The other element to Game Ready rigs, is removing features that are specific to Maya that a Game Engine cannot read. And this is where my problem lay. The facial rig on my Sylvanas character was constructed in a way that Unreal Engine could not recognise. 

And so I set out on a tireless 10 day research rabbit hole, filled with trial and error, experimentation and frustration. As I attempted to find a solution to the Face Rig Problem...

"Face geo not appearing in FBX export", "How to export face rig to Unreal", "How to convert vertex animation into Blend Shapes"

Countless stabs in the dark trying to stumble across some sort of solution. I wondered if it was possible to convert the vertex animation back into Blend Shapes, however this didn't seem viable. The only information I could find on exporting vertex animation was by baking a point cloud cache but after some testing I couldn't get this to work.

One file format that I know does support vertex animation however, is Alembic (.abc). I was hesitant to use Alembics since they've been weird for me in the past, but upon testing the export, I was able to successfully get the model and animations into Unreal Engine. Although, this presented a separate problem. Importing animated alembics into Unreal requires them to be imported as a Geometry Cache, and this would mean that I would not be able to use Unreal for my cloth simulations ( as the cloth paint feature requires the object to be a Skeletal Mesh). This posed me with a tough decision. Either return to Maya and figure out the nCloth method of simulation OR keep working to find an alternative solution for the face rig issue.

I decided to keep looking, figuring that if all else fails I could try and find some way to work with the Alembic.

I was beginning to lose hope at this stage, and was contemplating contacting the original rigging artist to see if they had a solution. I decided to search for some contact details, and when googling the Sylvanas rig again I found a separate download page uploaded by the rigging artist himself (Truong CG Artist). On this page he did have some contact details, but also a link to some How-to's that had not been present on the site I initially got the rig from. Considering he had provided them, I figured it best to go through the how-to's first, prior to contacting him, in case the questions I had were already answered.

The playlist contained around 120 tutorials, many made by Truong himself that covered a range of topics. The majority seemed irrelevant to my problems however skimming through the playlist I picked out a couple that I thought could give me some insight.

The title of the first video mentioned the Sylvanas rig by name (despite showing the Irex for the majority of the video) but ultimately just ended up being about hiding the controls. The second video however, was far more interesting...

After watching the video, I had learned a couple of things. Firstly, the term Advanced Skeleton (which I had heard being thrown around throughout my search) was not just a generic term, but the name of a software (AdvancedSkeleton5). Not only that, but it was the same software used to rig the Sylvanas character. The character in the tutorial features the exact same control setup and so with talk of exporting to game engines, I felt like I had perhaps stumbled upon the beginnings of a solution. 

I managed to download an older version of the software, which did feature the Simplify Face Setup button. However, I unfortunately could not get it to run without flagging up errors. At this point, I returned to the tutorials since I knew I was on the right track but was just coming up short.

Getting all the Geo to export was now possible but I still had trouble getting all the face shapes to import. This came down to an error on my part, as during the UE5 importing process, there was a tiny checkbox called 'Enable Morph Targets' that I had left unchecked. Once I figured this out however, I had facial animation in Unreal Engine. Hurray!

Still though, not everything was perfect...

There were however even further errors, which was the fact that my characters operate at different scales. To maintain accurate in engine measurements, I calculated that the Sylvanas rig needed a scale of 0.7. For some unknown reason, this caused problems with the nurbs surfaces which provided sluggish and unpredictable deformations. This made certain face shapes difficult to achieve which is why there is only very simple facial animation in the final film. Thankfully, the story didn't call for dialogue or a particularly emotive character, so I don't think I lost all too much.

Evaluation Modes:

Blink Issues:

Eyelash Export:

But then I discovered that the Eyelashes would still not import into Unreal with the rest of the face. I tried many different methods in an attempt to rectify this but ultimately conceded that it wasn’t too noticeable and that she may have to go without eyelashes.