Analysis > Compute Volume To Plane calculates the volume of a polygon object plus or minus the volume of the projection of the rim to a plane.
An open polygon object has a rim. A projection of the rim to the plane will give a projection volume. If the plane lies above the rim, this function gives the volume of the object plus the volume of the projection. If the plane lies below the rim, this function gives the volume of the object minus the volume of the projection.
In the diagram, there exists a cube-like object with a single opening on top. In the diagram, the rim is the edge of the dark gray rectangle. If the plane lies at position 1 above the rim, this function would give the volume of the entire cube plus the volume of the projection near callout A. If the plane lies at position 2 below the rim, this function would give the volume of the entire cube minus the volume of the projection near callout B.
The plane can be placed by a variety of methods.
The controls are:
Align Plane group - specifies a method of superimposing a plane on the object. See Methods of Superimposing Planes.
Volume - indicates the volume calculated by the special algorithm.
OK button - terminates the dialog.