Visual3D models segments as cones, cylinders, spheres, and ellipsoids. Visual3D doesn't compute the volume of a segment based on these geometries, but the calculations are straightforward in each case.

One of the Visual3D segment geometries is labeled a Cone or, to be precise, a conical frustrum. A frustra of right cones is created by cutting the top off of a cone such that the cut is parallel to the base of the cone. Given a conical frustrum defined as below:

Its volume is calculated as:

In Visual3D the inertial properties of an ellipsoid (sphere) are calculated using only the distal radius. For an ellipsoid defined as below, where L is the line between the segment's proximal end and its centre of mass,

Its volume is calculated as:

Finally, for an eliptical cylinder defined as:

Visual3D uses the radius at the distal end of the segment as the radius of the cylinder and calculates its volume as:

This segment volumes are not computed by default, but they can be added by the user as Model Metrics.

This can be done through the interface, for example for a segment with Cone geometry:

Or through the Set_Model_Metric pipeline command, for example for a segment with Elliptical Cylinder geometry:

Set_Model_Metric
/METRIC_NAME=Pelvis_Volume
! /METRIC_VALUE=PI*RPV_Seg_Length*RPV_Distal_Radius*RPV_Proximal_Radius/4
;

Go back to the Segment Overview for more information about segments in Visual3D.