What does the Runway Motion Brush do?

It lets you paint specific regions of a still image and assign each region a direction and amount of motion. Unpainted areas stay relatively still, so you control exactly what animates rather than letting the whole frame move.

How many brush strokes should I use?

Start with one stroke per independent motion. Water, hair, and clouds each get their own region. Too many overlapping strokes fight each other and produce warping, so keep distinct motions on distinct, non-overlapping areas.

How strong should motion intensity be?

Subtle ambient motion (water ripples, drifting smoke) wants low intensity, around 1 to 3. Deliberate movement like a turning head or walking figure needs more, but high intensity on detailed subjects like faces causes morphing, so raise it gradually.

Can I combine the brush with a text prompt?

Yes. The brush controls where and how things move; a short text prompt still guides overall style and any camera movement. Keep the prompt aligned with the brushed motion so they reinforce rather than contradict each other.

Runway Motion Brush Guide

Runway Motion Brush guide

Runway’s Motion Brush gives you region-level control over video generation: you paint the parts of a still image that should move and assign each one a direction and strength, while unpainted areas stay calm. This guide turns an animation goal into a concrete stroke plan — how many strokes, where to place them, and how much intensity to dial in.

How it works

The brush works in layers of independent motion. Each stroke defines a region and a vector (which way it drifts) plus an intensity value. Because the model respects your painted boundaries, the discipline is to keep distinct motions on distinct, non-overlapping regions: one stroke for rippling water, another for drifting clouds, another for a subject’s hair. Foreground subjects usually need lower intensity to avoid morphing, while background ambient elements can take stronger, looser strokes. A short text prompt still sets overall style and any camera movement.

Stroke planning tips

One stroke per motion. Independent movements get independent regions. Overlapping strokes fight and cause warping.
Protect faces and hands. These distort fastest. Use low intensity, or leave them unpainted so they stay still.
Match prompt to brush. If you brush leftward water flow, don’t write a prompt implying a still pond — keep them consistent.
Build up intensity. Start subtle, preview, then raise strength only where the motion reads as too static.