This example illustrates customisation of the fitted lung lobes using the host mesh fitting technique. Since the lung lobes have been fitted individually (see example 972), There is no guarantee of perfect contact between lobes. i.e. gaps and overlaps between lobes. The slave mesh (lung lobes) is completely embedded in a tri-cubic volume host mesh and the slave nodal positions can be defined using host element local coordinates. An objective function is then set up to minimise the summation of the square of the distances between the landmark(initial position) and target(final position) points in terms of host mesh nodal parameters. Any deformation that the host mesh undergoes will cause a similar change in the shape of the slave mesh as slave mesh is inside the host mesh. The new nodal values and the derivatives of the slave mesh are then updated with respect to the deformed host mesh. Note that using the host mesh fitting technique both Euclidean and Affine transformations can be performed on high-order meshes. A complete mathematical analysis of the method can be found in hostmesh_fit.pdf

The com file in this example is only for transforming the left lower lobe. For transforming of other lobes use the following com files.

left_upper.com , right_upper.com , right_middle.com , right_lower.com . All necessary input files can be found at the end of this page.

Created by Kumar Mithraratne.

Fig. 1 Fitted left lower lobe with undeformed host mesh Fig. 2 Transformed left lower lobe with deformed host mesh Fig. 3 Transformed Lung