The plane attribute plug-in function can calculate the centroid, area, perimeter, moment of inertia and radius of rotation of any surface in SketchUp. You can draw crosshairs as markers at the centroid.
Get Face Properties（Get Face Properties）动画教程
Select at least one suitable plane parallel to the red green axis and execute the command. For a plane with an internal opening, you must draw a connecting line between the opening and the edge of the plane before using this tool.
