Making realistic game characters: facial rigging

Character facial expressions can make or break a gaming experience. Nothing can ruin an otherwise graphically appealing game like those off-putting, uncanny valley facial twitches. As a game developer, consider these best practices by Santa Monica Studio for God of War when creating your realistic 3D characters.  

Get a good subject

Image courtesy of Santa Monica Studio

Image courtesy of Santa Monica Studio

If you plan on using motion capture (and you should) for your characters, the best way to ensure smooth-looking facial movements is with a good subject for facial rigging. As God of War’s Lead Character Technical Artist Axel Grossman put it, “Find someone who’s talented at moving their face, that can isolate muscle movements; this is very hard to do, probably 1 out of 10 people has 80% facial control across all their muscles.” Hold auditions and make sure your subject can meet the needs of your project.

Outsource blend shapes

Image courtesy of Santa Monica Studio

With such high resolution for games like God of War, large amounts of blend shape data is captured in the face and reflected in-game. The number of rigs in God of War averaged out to about 800 shapes, so remember that blend shape rig builds are going to require highly-skilled artists. While the team behind God of War took it upon themselves to create their own blend shapes, they don’t recommend doing this yourself for projects where the job can be outsourced.

Go the extra mile

Image courtesy of Santa Monica Studio

Image courtesy of Santa Monica Studio

Wrinkles and blood flow maps were used to add that extra layer of realism to some of the characters in God of War. If you’re looking to give your characters those nice finishing touches, creating a wrinkle and blood flow system can be just the thing. For God of War, three different wrinkle maps were made in ShaderFX, and ordered by priority so that the maps could ride on top of each other. The wrinkle maps serve to complement facial movements, adding things like crow’s feet to create a realistic smile. Taking the time to add those details to your character’s face can make all the difference.

Maximize your mocap data

Image courtesy of Santa Monica Studio

God of War has a whole stock of characters and creatures with faces that need to be rigged – but that doesn’t mean that every single monster and animal needs to have a unique set of facial movements. Having a way of transferring mocap data will save a lot of time and effort. Wear out your mocap data on as many characters as it can be transferred onto as possible, without sacrificing quality. Putting facial animation onto creatures, for example, is generally less challenging, since these types of characters don’t need to be quite as hyperrealistic.  

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