What will happen when you edit a spline defined Through Points to a spline defined By Poles?

When you edit a spline defined Through Points and change it to a spline defined By Poles, the defining data will be lost. This is because the two spline types represent different methods of defining their shapes. A Through Points spline actually uses specific points as critical locations that the spline will pass through, providing a direct relationship between the geometry and the control points. On the other hand, By Poles splines rely on a set of control points (or poles) that the spline does not necessarily pass through but instead influences its shape.

When converting from Through Points to By Poles, the connection to the specific points is severed, and the spline is redefined using the control points instead. This results in the original point-based defining data no longer being accessible in the same way. Although it might be possible to manually recreate a similar form based on the previous Through Points spline, the original data is not retained as part of the conversion process. This distinction underlines how essential it is to understand the differences in spline definitions when working within Siemens NX.