What do you call the volume of the cascade? If this is the number of V and SIA, if you have calculated them with OVITO, then you have their number.

If you really want the volume, then you should decide what is the geometry of the casade (sphere, ellipsoide, etc...). Then, from the coordinates of the V and SIA, you should be able to calculate the main axis and then the volume. In general, what I do is to assume it is an ellipsoide. If your cascade has different branches, then more complicated...

Best regards,

Christophe