Marker-based XROMM requires software tools for: (1) correcting fluoroscope distortion; (2) calibrating X-ray cameras; (3) tracking radio-opaque markers; and (4) calculating rigid body motion. In this paper we describe and validate XMALab, a new open-source software package for marker-based XROMM (C++ source and compiled versions on Bitbucket). Most marker-based XROMM studies to date have used XrayProject in MATLAB. XrayProject can produce results with excellent accuracy and precision, but it is somewhat cumbersome to use and requires a MATLAB license. We have designed XMALab to accelerate the XROMM process and to make it more accessible to new users. Features include the four XROMM steps (listed above) in one cohesive user interface, real-time plot windows for detecting errors, and integration with an online data management system, XMAPortal. Accuracy and precision of XMALab when tracking markers in a machined object are ±0.010 and ±0.043 mm, respectively. Mean precision for nine users tracking markers in a tutorial dataset of minipig feeding was ±0.062 mm in XMALab and ±0.14 mm in XrayProject. Reproducibility of 3D point locations across nine users was 10-fold greater in XMALab than in XrayProject, and six degree-of-freedom bone motions calculated with a joint coordinate system were 3- to 6-fold more reproducible in XMALab. XMALab is also suitable for tracking white or black markers in standard light videos with optional checkerboard calibration. We expect XMALab to increase both the quality and quantity of animal motion data available for comparative biomechanics research.
The authors declare no competing or financial interests.
E.L.B., D.B.B. and S.M.G. developed the initial concept for new X-ray motion analysis software, B.J.K. designed and wrote the XMALab software, B.J.K., E.L.B., D.B.B. and S.M.G. designed the accuracy, precision and reproducibility tests, B.J.K. and J.D.L.-C. collected and analyzed the accuracy and precision data, B.J.K. analyzed the reproducibility data and did all statistical tests, J.D.L.-C. and B.J.K. designed, built and tested the Lego calibration object, B.J.K. and E.L.B. wrote the manuscript and all authors read the manuscript, provided critical comments for revision and approved the final version.
This work was supported by the US National Science Foundation under grant numbers 1120967 and 1262156.
Data have been deposited in the XMAPortal (xmaportal.org), in the study ‘Data for Software and Hardware Validation’ with permanent ID BROWN17.
Supplementary information available online at http://jeb.biologists.org/lookup/doi/10.1242/jeb.145383.supplemental
- Received June 30, 2016.
- Accepted September 20, 2016.
- © 2016. Published by The Company of Biologists Ltd