Step 8 – For each centroid ci, the equation of a sphere Ei is computed so that it is centered on ci and has a radius proportional to the estimated ‘‘wire’’ thickness in the dilated voxel image.
In this work this parameter must be directly input and can be roughly estimated from the knowledge of the line thickness in the original 2D drawing,
the scanning resolution, and the number of dilation steps ns performed in Step 3.
The spheres are assumed to represent
the regions where the wires’ intersections lie. Accordingly,
in order to separate the ‘‘branches’’ composing the wireframe-like voxel model,
image T is ‘‘cut’’ by means of spheres Ei by setting T(i,j) = 0 for all the voxels lying inside any of the spheres.
The resulting image is characterized by the presence of a set of connected components representing the separated‘‘branches’’ of T.