Please show models for which extracting correct mid-surface (midsurface, medial) is difficult? Situations for which mid-surface shows gaps, overlaps etc.
One example of application for extraction of mid-surfaces is the preparation of geometry data for finite-elements simulation of automotive body in white. Here, challenges can be found in complex curved surfaces (including holes, beads and seams), different sheet metal wall thicknesses, connection technology (overlapping weld spot flanges and bonding flanges). In addition, multi-material componentes and components with variable wall thickness (e.g. casted junction plate) require more effort to extract the mid surfaces.