Center of Mass shouldn't be a zero-dimensional spatial region

[michaelrabenberg]

This may have come up at a meeting some time ago--I can't remember--but if the center of mass of an object can move with the object (as seems plausible), then Center of Mass shouldn't be a zero-dimensional spatial region.

A natural alternative, given current BFO/CCO machinery, would be to make it a fiat point.

Another less committal alternative would be to simply make it an immaterial entity (for the time being).

Either change would require changing the subclass relation as well as the textual definition.

[alanruttenberg]

This has come up before - we have discussed that many if not all the spatial regions should be continuant fiat boundaries. I use center of mass in my ontology work and have it as a fiat point. As a spatial region it can't have qualities.

[michaelrabenberg]

This should be labeled "for 2.1 release," right?

[cameronmore]

This is definitely not a spatial region.

[dlutz2]

Follow on to @alanruttenberg's comment re many other spatial regions being fiat boundaries, I believe all of below spatial regions (bolded) are fiat boundaries of the equivalent dimensions since their definitions include a relation to a material entity:

• spatial region
  • zero-dimensional spatial region
    • Center of Mass
    • Ground Track Point
    • Object Track Point
      • Vehicle Track Point
  • one-dimensional spatial region
    • Axis of Rotation
      • Pitch Axis
      • Roll Axis
      • Yaw Axis
    • Ground Track
    • Nadir
    • Object Track
      • Vehicle Track
    • Zenith
• three-dimensional spatial region
  • Three-Dimensional Path
  • Three-Dimensional Position

That leaves the below which seem to be or part of a Spatial Reference System (although I'm not sure how to interpret the "Ellipse" that is part of the (Semi-)Major/Minor Axes definitions. In any case, not obviously a spatial region):

• spatial region
  • one-dimensional spatial region
    • Coordinate System Axis
      • x-Axis
      • y-Axis
      • z-Axis
    • Major Axis
    • Minor Axis
    • Semi-Major Axis
    • Semi-Minor Axis

If we intend to move Center of Mass for 2.1, could we also move the other spatial regions to the appropriate location?

[alanruttenberg]

Even the coordinate system axes are always anchored relative to a material entity, so I don't think they belong in spatial regions either. It's just simpler if spatial region is ignored.