In this application video, a 4-cam MulticamDIC system is used to measure the range of motion of a
mandible. The focus of the measurement was to measure the jaw movement that isolates true mandibular
motion—that is, the movement of the mandible relative to the cranial base, after removing (or compensating
for) any head or body movement. As such, Rigid Body Motion (RBM) was removed from the visualization.
Using the MulticamDIC setup, the projection of all 4-cameras was calibrated in one coordinate system using
the Clustered Bundle-Adjustments Algorithm (CBAA) without using the Image Stitching Method (ISM). The
CBAA relinquishes inaccurate measurement of images that are stitched together from a coordinate system
transformation of common overlapping points between cameras.
In the correlation evaluation, the Object Alignment Parameterization (OAP) is selected which parameterizes
the grid directly on the object assuming a cylindrical shape of the skull. This means that facets/subsets do not
need to be aligned to a reference camera view and thus improves the measurement accuracy of the 3D-model.
In the startpoints search, the startpoints in the reference step can be selected/toggled for each relative,
overlapping camera view.
In the graphical visualization, it is clear that the mandible displaces & rotates independently from the cranium
(skull). From the temporal plot of the three point gauges of the; lower jaw, upper jaw, and jaw pivot, it can be
seen that the mandible displaces by 7 mm during the opening action. The jaw pivot displaces by 8 mm, and
interestingly, the rate of displacement is comparatively higher towards the end of the test at full opening.
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