Orbit

Drag across a 3D view and the model appears to spin. It does not. What moves is the camera, swinging around a fixed target point on the surface of an invisible sphere, and the object sits exactly where it always sat. That distinction is the whole reason the word exists. Horizontal travel changes the azimuth, the angle around the target, and vertical travel changes the elevation, the height the camera looks down from; the distance to the target is left alone, which is what keeps the subject the same size and in the middle of the frame while everything around it turns.

The two common flavours differ in what they do at the poles. A turntable orbit keeps a fixed world up direction and clamps the elevation short of straight up and straight down, so the horizon never rolls and the model never goes upside down. An arcball maps the drag onto a virtual sphere under the pointer and rotates freely, which is more expressive and much easier to get lost in: a few careless drags and the reader is somewhere no label can describe. Clamping looks like a limitation and is really the navigation aid. It is the difference between a view you can always talk your way out of and one that needs a reset button to rescue.

Orbit is one third of the standard camera set, and the other two are worth keeping distinct. Pan slides the target sideways, so the subject moves off centre. Zoom, or a dolly, changes the distance along the line of sight. Only orbit leaves both the target and the distance untouched. A rotate gesture is the near neighbour that trips people up most, and it is the opposite claim: there the content really does turn, in its own plane, and the camera never moves at all. If the thing that changed is which side of the object you can see, it was an orbit; if the thing that changed is which way up the object is, it was a rotation.

Because the gesture is continuous and unlabelled, an orbit needs a way home. A reset view control, a set of named viewpoints (front, top, three quarter), and keyboard steps for readers who cannot drag are all doing the same job: making a camera that can be anywhere also be somewhere describable. Momentum after the release is a taste decision, and a strong one is worth gating behind the reduced motion preference, since a view that keeps drifting after the hand stops is a reliable way to make a reader feel unwell.