Why is not userframe.floor vector4?

When I use kinect v2 or orbbec sdk, floor function or variable always return vector4 form.
But nuitrack return vector3 form.
As I remember, vector4.w is height of sensor.
Thanks in advance.

you can calculate a Vector4 from what NuiTrack gives:

Plane.W = - DotProduct( PlaneNormal, FloorPoint);

Do you mean floor plane normal ?