Flocking
systems
Film and VFX are all about studying nature, and finding a way to represent it to tell a story. Sometimes you can get directly hands on with that: model something, rig it, animate it. But at scale, the game changes. At a certain point you have to switch from manual to procedural, which normally means embracing a certain degree of technicality.
In industry, procedural behaviours are dominated by more technically minded artists, and that can sometimes lead to problems, because the root of everything is studying nature.
Bear that in mind as we explore flocking systems, which is how we create groups of flying or swimming creatures in VFX.
Each creature is a boid, short for "bird-oid," meaning a bird-like object. The boid may be driven by some basic animation of its own, like the flapping of wings, but the real power comes from its behaviour in relation to all the other boids.
In this sheet, we're going to look at the main ways you can influence that behaviour.
In production, creating flocks is relatively simple and lightweight. Sometimes they are done in 3D packages and rendered, but they can also be done in compositing packages, and a comp artist with the right know-how can easily sneak a few birds across the background of a shot to give it a bit more depth and life.
The flock is controlled by three main rules: separation, alignment, and cohesion.
Separation is how close the boids will tolerate being to their neighbours.
Alignment is how closely a boid matches its heading to the average heading of its neighbours.
Cohesion is the unity of the whole group. Higher cohesion pulls the boids in towards the middle (a high separation will have them still keeping their distance even as they crowd towards that middle).
Weights
Export to Blender
What you are seeing
This is a really important part of naturalistic groupings: the animals don't have a hive mind, they react to what they can see. In this example, a bird won't be influenced by birds it can't see, but eventually every bird sees every other bird, and a similar behaviour spreads through the flock anyway, just in a very organic way.
Perception
Counting method
Never work with children or animals, they say. THEY clearly never had a good flocking system. Here's how you direct birds (and fish, and anything else that is flocky). Direction comes from what you add on top: somewhere to go, something to fear, something in the way. Tap the plate to place them, drag to orbit. Pillars are columns that run floor to ceiling, so the flock has to go around rather than over.
What to place
Strength
Export to Blender
Everything should come from studying nature, and everything, not just flocking, should be simplified and layered. Here's a bunch of layers to consider. Turn them on one at a time and watch the read change.