Precise knowledge of the mid-sagittal plane is important for the assessment and correction of several deformities.
Furthermore, the mid-sagittal plane can be used for the definition of standardized coordinate systems such as pelvis or
skull coordinate systems. A popular approach for mid-sagittal plane computation is based on the selection of anatomical
landmarks located either directly on the plane or symmetrically to it. However, the manual selection of landmarks is a
tedious, time-consuming and error-prone task, which requires great care. In order to overcome this drawback, previously
it was suggested to use the iterative closest point (ICP) algorithm: After an initial mirroring of the data points on a
default mirror plane, the mirrored data points should be registered iteratively to the model points using rigid transforms.
Finally, a reflection transform approximating the cumulative transform could be extracted. In this work, we present an
ICP variant for the iterative optimization of the reflection parameters. It is based on a closed-form solution to the least-squares
problem of matching data points to model points using a reflection. In experiments on CT pelvis and skull
datasets our method showed a better ability to match homologous areas.
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