Figure 1.
Setup of the measuring devices.
The setup of the two measurement devices, placed 2 meters behind the measured test subjects. The rasterstereographic system is contained within a column (A), which contains the infrared-flash, the light projector and the digital camera. The VICON system consists of three cameras (B), each equipped with an infrared-flash for the marker detection.
Figure 2.
Marker placement on test subjects.
The placement of the 12 markers (white dots) on the back of a measured test subject are shown. The markers were placed so that they formed four triangles, of which the sides were determined by the detection of the markers by the tested systems. Triangle 1 (T1): between the scapula, defined by M1, M2, M3. Triangle 2 (T2): below the scapula, the thoracic spine (M4, M5, M6). Triangle 3 (T3): the lumbar spine (M7, M8, M9). Triangle 4: from the VP to the two lumbar dimples (M0, M10, M11).
Table 1.
Distances on a solid plate.
Table 2.
Side lengths measured with the two devices during motion.
Figure 3.
Accuracy of marker detection under static conditions.
The mean differences of the measured sides of the four triangles during standing. The smallest differences in the marker detection were found in triangle 2 with a difference of −0.23 mm and the biggest differences were found in triangle 4 with a difference between the two systems of 1.02 mm. No measured side lengths of the triangles differed significantly.
Figure 4.
Accuracy of marker detection under dynamic conditions.
The measured sides of all four triangles during motion with subjects walking at speeds of 1.5, 3 and 6 km/h. There were no significant differences (p>0.05) in the measured segments of the triangles between the two systems.