Mathematically there are various ways to calculate a spacial center point. (2d or 3d).
- Barycenter (sum of all positions divided by the total number of points)
- Bounding box center (typically the middle of the bounds on each axis).
- Center of mass (exact calculation depends how mathematically accurate you want to be, weighting by edge-length can be used for example, for 3d volumes face area can be used).
For the purpose of a graphical application rotation or scale pivot point (for non-technical users),
what are acceptable terms for different kinds of 2d / 3d center?
The application uses all these kinds of center, and the target audience is artists / animators (possibly architects, engineers too, though thats less of a focus).