Weighting mesh vertices to a skeleton — each point follows bones with defined influence radius. The difference between rigid and organic animation.
On set, we work with real bodies; in the VFX studio, with point clouds. Skinning is the craft in between – the moment a digital skeleton gets its skin. You define how strongly each individual vertex of the mesh reacts to the rotation and position of the underlying bones. Without this weighting system, your character would tear with every movement or deform like plastic. With correct skinning, the flesh follows organically.
The practice: You import your digital model with its thousands of vertices into your rigging program. The skeleton is already underneath – spine, shoulders, arms, legs. Now you have to decide: The vertex at the shoulder should follow the torso bone 70 percent, the arm 30 percent. The elbow bone gets a significantly smaller area of influence, otherwise the transitions become muddy. You paint these weights directly into the mesh – in most tools with a brush and a color value between 0 (no influence) and 1 (full influence). The most difficult areas are always the joints: elbows, shoulders, hips. There you need multiple overlapping bone influences, otherwise you'll see harsh edges during movement.
A classic mistake in the set comparison: A rigidly modeled figure without skinning looks like a wooden action figure. With skinning, you suddenly get flexibility – the thigh can bend naturally without the thigh flesh shrinking abnormally. You usually work iteratively: The model animator performs initial tests, you see vertex cage artifacts or overly soft deformations, and correct the weights. For complex characters – with clothing, armor, hair – skinning becomes an art. Each layer needs its own weighting, otherwise fabric and body will collide later, or the armature will tear the dress.
The final result is measured in motion tests. Your animator moves the arm, and you see: Does the shoulder follow? Does the upper arm stretch unnaturally? Are there pole vector issues with fast rotations? Good skinning is invisible – the viewer only sees natural movement, not your vertex work behind it. Bad skinning destroys the entire shot.