X-Ray reconstruction of moving morphology (XROMM): Precision, accuracy and applications in comparative biomechanics research

Elizabeth L. Brainerd, David B. Baier, Stephen M. Gatesy, Tyson L. Hedrick, Keith A. Metzger, Susannah L. Gilbert, Joseph J. Crisco

Research output: Contribution to journalArticle

224 Scopus citations


X-Ray Reconstruction of Moving Morphology (XROMM) comprises a set of 3D X-ray motion analysis techniques that merge motion data from in vivo X-ray videos with skeletal morphology data from bone scans into precise and accurate animations of 3D bones moving in 3D space. XROMM methods include: (1) manual alignment (registration) of bone models to video sequences, i.e., Scientific Rotoscoping; (2) computer vision-based autoregistration of bone models to biplanar X-ray videos; and (3) marker-based registration of bone models to biplanar X-ray videos. Here, we describe a novel set of X-ray hardware, software, and workflows for marker-based XROMM. Refurbished C-arm fluoroscopes retrofitted with high-speed video cameras offer a relatively inexpensive X-ray hardware solution for comparative biomechanics research. Precision for our biplanar C-arm hardware and analysis software, measured as the standard deviation of pairwise distances between 1mm tantalum markers embedded in rigid objects, was found to be 70.046mm under optimal conditions and 70.084mm under actual in vivo recording conditions. Mean error in measurement of a known distance between two beads was within the 0.01mm fabrication tolerance of the test object, and mean absolute error was 0.037mm. Animating 3D bone models from sets of marker positions (XROMM animation) makes it possible to study skeletal kinematics in the context of detailed bone morphology. The biplanar fluoroscopy hardware and computational methods described here should make XROMM an accessible and useful addition to the available technologies for studying the form, function, and evolution of vertebrate animals.

Original languageEnglish (US)
Pages (from-to)262-279
Number of pages18
JournalJournal of Experimental Zoology Part A: Ecological Genetics and Physiology
Volume313 A
Issue number5
StatePublished - Jun 1 2010

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Animal Science and Zoology
  • Molecular Biology
  • Genetics

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