A study on the degrees of freedom in touchless interaction

During the last few years, we have been witnessing a widespread adoption of touchless technologies in the context of surgical procedures. Touchless interfaces are advantageous in that they can preserve sterility around the patient, allowing surgeons to visualize medical images without having to physically touch any control or to rely on a proxy. Such interfaces have been tailored to interact with 2D medical images but not with 3D reconstructions of anatomical data, since such an interaction requires at least three degrees of freedom. In this paper, we discuss the results of a user study in which a mouse-based interface has been compared with two Kinect-based touchless interfaces which allow users to interact with 3D data with up to nine degrees of freedom. The experimental results show that there is a significant relation between the number of degrees of freedom simultaneously controlled by the user and the number of degrees of freedom required to perform, in a touchless way, an accurate manipulation task.