Figure 2From: Accuracy assessment of Tri-plane B-mode ultrasound for non-invasive 3D kinematic analysis of knee joints (a) Reference sensor local coordinate system, where the z -axis directs into the page and not shown, (b) out-of-plane rotation (about the z -axis), the rotated H-shaped sensor (lighter in color) overlaid on initial position (dark) and (c) more general case, where the center of rotation, o shifted along slice CC’ . Back to article page