Most 3d games use pre-rendered geometry when avatars walk around swing swords etc. Being able to add highly accurate facial movements to those animations incre

Most 3d games use pre-rendered geometry when avatars walk around swing swords etc. Being able to add highly accurate facial movements to those animations increases realism without needing all that much data relative to modern hardware. And unlike simple video clips you can meld these things into the rest of the games geometry so say a grunts cheek would react reasonably as they lifted their AK to fire on you.