Arc Finder Parts of the Arc Finder Region of Interest The Arc Finder outputs the following results: ACEUser's Guide, 3.6.x, 18316-000 Rev A Page 398 Object Definition Instance Index of the result instance (numbered from 0). Frame/Group The frame or group to which the result belongs. Arc X The X coordinate of the point midway between the ends of the found arc. Arc Y The Y coordinate of the point midway between the ends of the found arc. Radius The radius of the found arc, Arc X, Arc Y being the center of the circular arc described by the found arc. Opening The angle of the found arc. Rotation The rotation of the region of interest.