A new video on Game Informer talks with two members of the Assassin's Creed Unity team tasked specifically with creating Paris' gigantic crowds about the technology that allowed them to build a scene with 12,000 AI models.
Meet Arno, The Protagonist Of Assassin's Creed Unity
Go ahead and read that number again, and take a moment to realize that I did, in fact, insert the correct number of zeroes there. The scene in question is modelled after a real historical event that included the attendance of thousands upon thousands of people. And Ubisoft, historical sticklers that they are, harnessed the awesome power of new-gen systems to recreate the event with a veritable flood of characters surrounding Arno on the streets of Paris.
According to Unity AI lead Aleissia Laidacker in the video, the entire city of Paris in the game includes 30,000 people, almost half of which can be on screen at the same time. For those keeping track at home, the population of Paris in Unity is around 4.5 percent of the actual estimated population of Paris at that time.
Assassin's Creed Unity Is Doing Away With Counter Kills And Kill Chains
Unity accomplishes this impressive screen count by only fully rendering those characters closest to Arno. The 100 closest models to the protagonist are rendered using the game's full range of animation. Characters who are farther away from the action are treated to a decrease in bone count, giving them a much more basic range of animation. This, combined with the processing power of modern consoles, means Arno gets to wade through a sea of thousands of character models to reach his goal. If you've never had the distinct displeasure of trying to get around while being surrounded on every side by people, Unity might be able to give you a good idea.
The video also goes into the AI details of Unity's crowds. When they're not too busy being numerous enough to fill up the average private university, Unity's AI characters have goals of their own in the city. They actively go places instead of following circuitous paths, and they interact with the world around them, even if you decide not to interact with them. They can even hold hands with each other (which is apparently a huge deal and longtime goal for Assassin's Creed dev teams).
The underlying theme of Assassin's Creed games has always been about hiding in plain sight. Even as far back as the first game, the narrative has emphasized blending with crowds and using large groups of people to disguise the fact that you're a highly wanted killer from the average passerby. In all games up until this point, this blending concept has been nothing more than making your way from one group of three people to another, nearby group of three people, somehow tricking guards into believing you've vanished. With crowds like Unity's, though, disappearing into a group of people suddenly seems plausible.
