Shrink-wrapping is nominally the process of deflating a virtual balloon around a polygon mesh or point cloud to create a tight-fitting watertight envelope containing only the external polygon faces of the original model.
As can be seen from the images, “nominally” is quite an important qualifier. Although Polygonica starts from an external convex mesh the advanced algorithms can respect holes and gaps in the model producing a result that is very close to the original exterior envelope.
There are many potential uses for shrink-wrapping which cover a variety of use-cases in a variety of markets:
Healing for Additive Manufacturing
Shrink-wrap can be used to heal triangle soups that have lots of disconnected or self-intersecting internals, examples including large architectural assemblies. A good quality shrink- wrap algorithm will make the model watertight and preserve the external faces so that the model could be 3D printed, for example.
Data optimisation for VR/AR/Mixed Reality
Typical mechanical CAD assemblies are often too large and detailed for the fast stereo framerates that give a great VR experience. Polygonica's new shrink wrap routines can remove the internal data before simplification allowing realistic levels-of-detail (LOD) built from only a few percent of the polygons contained in the original model.
This level of data reduction is ideal for workflows in which large mechanical assemblies need to be displayed in even bigger datasets - for example buildings, factories, process plants, power plant, ships and other offshore structures.
Point cloud meshing for geotechnical industries
Polygonica's shrink wrap routines can close very large holes whilst also removing unwanted internal data. This can be the optimal way to create good quality watertight meshes from sparse scan data typical in geotechnical industries.
Clash detection for dynamic scenes and 3D packing
By removing internals and then decimating the results within a defined tolerance very accurate but lightweight proxies can be created to improve clash detection performance e.g. for factory simulation or 3D packing algorithms for Additive Manufacturing etc.
Polygonica’s shrink-wrapping and decimation algorithms can optionally ensure all parts of the resultant mesh are external to the original mesh so that no clashes are missed.
Defeaturing for IP protection
By removing the internals of an assembly the author is helping to protect intellectual property when distributing to external third parties.
Shrink-wrapping in Polygonica:
Shrink-wrapping was introduced in Polygonica 2.2 in September 2018. Since then development has continued to produce cleaner-looking wraps that more closely fit the faces of the original model. Although not yet released this work is available for testing by suitably qualified early adopters.
If shrink-wrapping is of interest then we’d love to hear from you.
Wind turbine model courtesy of Davor Jovanovićz (https://grabcad.com/library/wind-turbine-100). Model modified by MachineWorks Ltd.