SphericalRegion is an option for three-dimensional graphics functions which specifies whether the final image should be scaled so that a sphere drawn around the three-dimensional bounding box would fit in the display area specified.
SphericalRegion -> False scales three-dimensional images to be as large as possible, given the display area specified.
SphericalRegion -> True scales three-dimensional images so that a sphere drawn around the three-dimensional bounding box always fits in the display area specified.
The center of the sphere is taken to be at the center of the bounding box. The radius of the sphere is chosen so that the bounding box just fits within the sphere.
With SphericalRegion -> True, the image of a particular object remains consistent in size, regardless of the orientation of the object.
SphericalRegion -> True overrides any setting given for ViewCenter.