The Reference Point subnode is available only when there is an available incident field defined in the parent node. Then this subnode is available from the context menu (right-click the Scattering Boundary Condition or Matched Boundary Condition parent node) or from the Physics toolbar, Attributes menu.

The Reference Point subnode defines a reference position rref that is calculated as the average position from the point selection in the Reference Point subnode or as a user-defined position on the parent feature boundary.

Select the points that should be used when calculating the reference position. The reference position is calculated as the average position of the selected points. The point selection is only effective when Definition in the Reference Point section is set to Point selection.

Select the Definition for the reference point — Point selection (the default) or User defined. When User defined is selected, enter the expressions for the components for the Reference point r0. The Reference point must be a point on the parent feature’s boundary selection.