Accuracy Comparison: Optoelectronic Motion Capture and Markerless System

Condition(s) studied

Investigational drug(s) / intervention(s)

Measure gait spatiotemporal parameters and kinematics from optoelectronic system: The raw data acquired from motion capture system were processed with Smart Analyzer software (BTS Bioengineering, Milano, Italy). First, the 3D data were filtered and interpolated in case of missing data for short time. Then spatial-temporal parameters (cycle duration, cadence, gait speed, stance phase, swing phase, double-support phase, stride length and step width) and conventional kinematic parameters of traditional Davis marker-set protocols were computed.

Measure gait spatiotemporal parameters and kinematics from markerless system: The two videos were elaborated using OpenPose that returns a set of 25 2D keypoints coordinates for body pose estimation for each video. Key-points were located in relevant body landmarks and it were used to determine the 2D Cartesian coordinates on the sagittal plane and on the frontal plane. The data calculated with routines were filtered and interpolated in case of missing data. With respect to kinematic parameters, the segment and joint angles were measured from the estimated feature points of each joint. Spatiotemporal gait parameters were calculated using successive heel strike and toe-off events.

Quantify tip toe step during gait from kinematic: The kinematic features calculated are used to identify and count the number of tip toe steps during gait or standing

Study summary

The purpose of this study was to assess the Openpose reliability to measure kinematics and spatiotemporal gait parameters and to evaluate the minimum technical requirements. This analysis used video and optoelectronic motion capture simultaneously recorded. We assessed more of 20 subject with different motor gait impairments

Eligibility

Primary outcome measure(s)

• Absolute Error — Through study completion, an average of 1 year
  Absolute errors were calculated for the kinematics parameters and for each spatiotemporal variable by taking the absolute value after subtracting the values obtained using pose estimation methods from the value measured using markerbased motion capture
• intraclass correlation coefficients — Through study completion, an average of 1 year
  To confirm whether the data obtained by OpenPose agreed with the data from the optoelectronic system, investigators calculated the ICCs (two-way mixed effects model, absolute agreement, average measurements) between the spatiotemporal and kinematic data from both systems. The ICC values were interpreted as follows: poor agreement for ICC \< 0.5, moderate agreement for values between 0.5 and 0.75, good agreement for values between 0.75 and 0.9, and excellent agreement for values greater than 0.90.
• cross-correlation coefficients — Through study completion, an average of 1 year
  The cross-correlation coefficients (CCC) between both systems were used to evaluate the similarity of angles during the gait cycle. The CCC values were interpreted as follows: weak or no coupling for values between -0.3 and 0.3, moderate coupling for values between 0.3 and 0.7 or -0.7 and -0.3, and strong coupling for values greater than 0.7 or less than -0.7.

Trial sites (1)

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