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Reproducible Optical Tracking Precision: Evaluating a Static, Near-Parallel Support Structure for OptiTrack PrimeX22 Cameras

Oliver Krumpek, Ole Kroeger, Sebastian Mohr

TL;DR

The paper addresses reproducible high-precision optical tracking by designing a static, rigid three‑camera support for OptiTrack PrimeX22/X22 systems using CFRP and Invar materials. It combines FEM‑validated design with near‑parallel camera geometry and two calibration/validation experiments to quantify how distance, camera separation, and motion speed affect measurement accuracy. Key findings show line‑of‑sight errors dominate along the z‑axis, achieving about ±0.74 mm along the line of sight and ±0.12 mm orthogonally in optimized configurations, with plane noise in the 0.02–0.07 mm range and improvements from increased camera separation. The work provides a modular, publicly available solution that enhances reproducibility for industrial automation and medical device tracking, while highlighting areas for future study such as long‑term stability and rotational accuracy.

Abstract

This paper presents the design and evaluation of a physical support structure for the OptiTrack X22 tracking systems, constructed from carbon fiber-reinforced polymer (CFRP) and Invar steel. These materials were chosen for their low thermal expansion, ensuring geometric stability and rigidity necessary for accurate spatial measurements. The support system is scalable and adaptable for various applications and setups. The study further investigates the effects of camera placement and separation in near-parallel configurations on measurement accuracy and precision. Experimental results show a significant correlation between camera distance and measurement precision - closer camera setups yield higher precision. The optimized camera arrangement allowed the prototype to achieve accuracies of +/-0.74 mm along the camera's line of sight and +/-0.12 mm in orthogonal directions. The experiments show that the standard deviation of the noise on a single measurement plane orthogonal to the camera's line of sight vary between 0.02 and 0.07, indicating that the measurement noise is not constant for every point on that specific plane in the meanurement space. Details of the system's design and validation are provided to enhance reproducibility and encourage further development in areas like industrial automation and medical device tracking. By delivering a modular solution with validated accuracy, this work aims to promote innovation and practical application in precision tracking technology, facilitating broader adoption and iterative improvements. This approach enhances the accessibility and versatility of high-precision tracking technology, supporting future progress in the field.

Reproducible Optical Tracking Precision: Evaluating a Static, Near-Parallel Support Structure for OptiTrack PrimeX22 Cameras

TL;DR

The paper addresses reproducible high-precision optical tracking by designing a static, rigid three‑camera support for OptiTrack PrimeX22/X22 systems using CFRP and Invar materials. It combines FEM‑validated design with near‑parallel camera geometry and two calibration/validation experiments to quantify how distance, camera separation, and motion speed affect measurement accuracy. Key findings show line‑of‑sight errors dominate along the z‑axis, achieving about ±0.74 mm along the line of sight and ±0.12 mm orthogonally in optimized configurations, with plane noise in the 0.02–0.07 mm range and improvements from increased camera separation. The work provides a modular, publicly available solution that enhances reproducibility for industrial automation and medical device tracking, while highlighting areas for future study such as long‑term stability and rotational accuracy.

Abstract

This paper presents the design and evaluation of a physical support structure for the OptiTrack X22 tracking systems, constructed from carbon fiber-reinforced polymer (CFRP) and Invar steel. These materials were chosen for their low thermal expansion, ensuring geometric stability and rigidity necessary for accurate spatial measurements. The support system is scalable and adaptable for various applications and setups. The study further investigates the effects of camera placement and separation in near-parallel configurations on measurement accuracy and precision. Experimental results show a significant correlation between camera distance and measurement precision - closer camera setups yield higher precision. The optimized camera arrangement allowed the prototype to achieve accuracies of +/-0.74 mm along the camera's line of sight and +/-0.12 mm in orthogonal directions. The experiments show that the standard deviation of the noise on a single measurement plane orthogonal to the camera's line of sight vary between 0.02 and 0.07, indicating that the measurement noise is not constant for every point on that specific plane in the meanurement space. Details of the system's design and validation are provided to enhance reproducibility and encourage further development in areas like industrial automation and medical device tracking. By delivering a modular solution with validated accuracy, this work aims to promote innovation and practical application in precision tracking technology, facilitating broader adoption and iterative improvements. This approach enhances the accessibility and versatility of high-precision tracking technology, supporting future progress in the field.

Paper Structure

This paper contains 14 sections, 10 figures, 1 table.

Table of Contents

  1. Introduction
  2. Contributions
  3. Related Work
  4. Design Considerations and Material Selection for Camera Support Structure
  5. Experimental Setup
  6. System Calibration
  7. Experiment 1: Investigation in different camera setups
  8. Experiment 2: Measurement Accuracy for Linear Displacements
  9. Results
  10. Observation 1: Increased Measurement Noise with decreased Camera Count and increased Tracker Velocity
  11. Observation 2: Decreased Measurement Precision with Increased Measurement Distance
  12. Observation 3: Mitigating Precision Loss at Greater Distances by Increasing Camera Separation
  13. Observation 4: Heightened Error in Tracking Movements Along the Camera's Line of Sight
  14. Discussion

Figures (10)

  • Figure 1: Photograph of the presented system in a realistic environment performing measurements on industrial robots
  • Figure 2: Initial development of the support structure, illustrating the foundation for further refinement. This version was found to be costly and prone to structural damage.
  • Figure 3: Photo of the final support structure mounted to a camera stand with a Manfrotto camera . A printable version is available on our github repository.
  • Figure 4: Detailed view of the fastening elements and the screw fittings
  • Figure 5: Wireframe of the support structure we presented for the use with three OptiTrack X22
  • ...and 5 more figures