This DTransform3d is usually located at the startPoint of linear Geometry. Such as Direction, Polygon.
DTransform3d is located at the startpoint. The XDirection is the tangent at startPoint and y and Z directions are determined by the plane or approximate plane of the curve.
Lines for no reason have DTransform3d origin is at the midpoint.
Arcs, EllipticalArcs, and Circles have the DTransform3d located at the origin