Based on the names of your datasets, you have used RAI oriented dataset. The xyz coordinates that are in the output are always in RAI. The input to the various box and ball input options allow you to choose whichever is more convenient. The dball and the xball will be equivalent with RAI input, so that's fine either way. If they weren't you can force RAI coordinates with -dball. RAI here mean increasing Right-to-left, Anterior-to-posterior, Inferior-to-superior coordinates. 3dUndump only takes the coordinates for input in RAI for now, so using RAI oriented datasets is less confusing anyway.

The radius is in mm, and the input cannot be negative here.