Physically correct jumps — measured before and after.

You key a jump and it looks floaty: the character hangs at the top, then drops; the take-off has no push; the spin in the air goes at the same speed whether the body is tucked or stretched. Gravity is the one thing every viewer feels and nobody can see in the graph editor. Fixing it by hand means guessing a parabola for a point you cannot see — the centre of mass.

Momentum finds the jumps in your animation, puts the centre of mass on a ballistic arc, blends the push-off and landing so the body does not jerk, keeps planted feet where you put them and conserves spin in the air. Every change is shown as a number before and after. When a jump cannot be made physical, it changes nothing and tells you why.

What it corrects

• Flight. The centre of mass follows a parabola with gravity of 9.81 m/s², in your scene's units and frame rate. Your poses stay; only the root moves.
• Push-off and landing. The difference is blended into the frames before take-off and after landing, so the velocity of the body never jumps more than it did in your animation, and the ground is never asked to pull the body down harder than 1.1 g unless your own animation already did.
• Planted feet. Feet on the ground stay where you put them — on Rigify through its IK foot controls, on FK skeletons through two-bone IK of thigh and shin.
• Spin. In the air the angular momentum is conserved: tuck in and the body turns faster, open up and it slows down. The take-off and landing orientation stay exactly as you animated them.
• Too floaty for its height? First Momentum keeps your timing and moves the body onto the arc. If that does not pass its checks and Allow Retiming is on, it tries changing the time in the air (keeping the height) before it refuses.

Measured, not promised

All numbers below are measured on Momentum's own model of the body (segment table or measured mesh) — the same model the panel reports in.

• Our test set: 43 jumps, two Blender versions. 10 hand-keyed jumps (small and high hops, a long jump, a sideways jump, double hops, one-legged hops, a 180° turn, a jump onto a box, a 300-frame clip) on four rig setups — generated Rigify, a Mixamo-style FBX with a mesh, the same at object scale 0.01, und eine BVH-Skelett — plus drei CMU motion-capture clips (a forward jump, jumping jacks, a run). On Blender 4.2.9 and 5.2.2 alike, 42 were corrected; on the run, the correction did not pass the checks (worst frame 1.7–1.8% off gravity), so Momentum changed nothing and said so.
• Gravity in flight: before the correction the worst frame of each flight was 62–510% off; after it, at most 0.07% (median 0.004%).
• Planted feet moved at most 0.39 mm.