It is possible to include any regression equations for the inertia and center of mass because Visual3D allows the user to put expressions into the edit boxes.

Consider a typical right thigh segment, which is populated with the default inertial values.

If the user selects this segment to be a CUSTOM_SEG, the edit boxes can be edited.

In this example we consider a conical segment:

We will create an expression for the Axial component of the center of mass based on the default computations described elsewhere in the documentation.

For convenience create a new Subject Metric X and enter the following expression:

RTH_DISTAL_RADIUS/RTH_PROXIMAL_RADIUS:

We can then use the Subject Data Metric X that we just created in another expression. Enter the following expression into the Segment Properties Axial edit box:

(1+2*X+3*X^2)/4/(1+X+X^2)*RTH_SEG_LENGTH

Note: the edit box doesn't show the entire expression, which is a nuisance