Effect of position on precision within the recording field of a markerless motion capture system

Carignan, Benoit, Lauzé, Martine, Lavigne-Pelletier, Catherine, Nguyen, Hung, Frossard, Laurent, & Duval, Christian (2015) Effect of position on precision within the recording field of a markerless motion capture system. In International Society for Posture and Gait Research (ISPGR) World Congress, 28 June - 2 July 2015, Seville, Spain.

Abstract

Introduction

Markerless motion capture systems are relatively new devices that can significantly speed up capturing full body motion.

A precision of the assessment of the finger’s position with this type of equipment was evaluated at 17.30 ± 9.56 mm when compare to an active marker system [1].

The Microsoft Kinect was proposed to standardized and enhanced clinical evaluation of patients with hemiplegic cerebral palsy [2].

Markerless motion capture systems have the potential to be used in a clinical setting for movement analysis, as well as for large cohort research. However, the precision of such system needs to be characterized.

Global objectives

• To assess the precision within the recording field of the markerless motion capture system Openstage 2 (Organic Motion, NY).

• To compare the markerless motion capture system with an optoelectric motion capture system with active markers.

Specific objectives

• To assess the noise of a static body at 13 different location within the recording field of the markerless motion capture system.

• To assess the smallest oscillation detected by the markerless motion capture system.

• To assess the difference between both systems regarding the body joint angle measurement.

Methods

Equipment

• OpenStage® 2 (Organic Motion, NY)

o Markerless motion capture system

o 16 video cameras (acquisition rate : 60Hz)

o Recording zone : 4m * 5m * 2.4m (depth * width * height)

o Provide position and angle of 23 different body segments

• VisualeyezTM VZ4000 (PhoeniX Technologies Incorporated, BC)

o Optoelectric motion capture system with active markers

o 4 trackers system (total of 12 cameras)

o Accuracy : 0.5~0.7mm

Protocol & Analysis

• Static noise:

o Motion recording of an humanoid mannequin was done in 13 different locations

o RMSE was calculated for each segment in each location

• Smallest oscillation detected:

o Small oscillations were induced to the humanoid mannequin and motion was recorded until it stopped.

o Correlation between the displacement of the head recorded by both systems was measured. A corresponding magnitude was also measured.

• Body joints angle:

o Body motion was recorded simultaneously with both systems (left side only).

o 6 participants (3 females; 32.7 ± 9.4 years old)

• Tasks: Walk, Squat, Shoulder flexion & abduction, Elbow flexion, Wrist extension, Pronation / supination (not in results), Head flexion & rotation (not in results), Leg rotation (not in results), Trunk rotation (not in results)

o Several body joint angles were measured with both systems.

o RMSE was calculated between signals of both systems.

Results

Conclusion

Results show that the Organic Motion markerless system has the potential to be used for assessment of clinical motor symptoms or motor performances

However, the following points should be considered:

• Precision of the Openstage system varied within the recording field.

• Precision is not constant between limb segments.

• The error seems to be higher close to the range of motion extremities.

Impact and interest:

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ID Code: 91566
Item Type: Conference Paper
Refereed: Yes
Additional URLs:
Keywords: Parkinson, Kimematics
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > HUMAN MOVEMENT AND SPORTS SCIENCE (110600) > Biomechanics (110601)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Current > Schools > School of Exercise & Nutrition Sciences
Copyright Owner: Copyright 2015 [please consult the author]
Deposited On: 04 Jan 2016 04:25
Last Modified: 06 Jan 2016 05:05

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