New tools for visualization of human motion trajectory in quaternion representation

The paper presents the results of research on the development of a framework and new tools for perceptually oriented visualization of human motion, in particular, a gait. Presented in this paper are new tools for visualizing motion and gait of a human. Their implementation is based on the following principles: i) translational motion component is omitted and time-varying orientations of individual parts of the body are represented by the trajectories of quaternions, ii) the trajectories of quaternions are visualized using a maps: S ³∈→∈ 3 implemented as: orthogonal projection, stereographic projection, Hopf transformation. This paper describes only the basic functionalities of the tool, the rest are easy to elicit from the main application screen. Rotations of a rigid body represented by the "3D one" about an axis defined by selected vector are presented as an example of using the tool and to facilitate understanding of motion visualization. Finally the exemplary gait visualisations based on three different maps for healthy subjects and patients with impaired movement are presented. Trial carried out using data from the gait laboratory HML show that the best approach to qualitative and quantitative analysis is based on using orthogonal projection. Other types of maps like Hopf and stereographic are difficult to interpret and may be useful in more specific cases.