The shrink wrap function will attempt to wrap your mesh inside a new mesh closely approximating the surface of the existing mesh. With the accuracy parameter you control the size of the sampling grid that is used to generate the replacement surface. The program indicates what your approximate mesh triangle size will be with the used accuracy setting. If your accuracy is low the calculation goes faster. Please note that if your accuracy is to low you might lose detail.
Reducing your mesh speeds up further computation. Certainly for large meshes (50mb+) it might be usefull to reduce your mesh. You can choose to reduce by triangles or vertices. Dialog indicates how many triangle/vertices will be removed. The algorithm does this by minimizing the difference (error) between the new and old mesh.
SPLIT DISJOINT MESH
The split disjoint mesh command splits a part into it’s disjoint parts. It analyses your parts triangles and detects which parts of the object are separate shells. You can use this if you want to import meshes that are multiple parts combined or if you want fine tune a combined part. Please note that you can’t use this on parts which have supports or other attached objects
JOIN DISJOINT MESH
The join disjoint mesh command joins multiple parts in 1 single part. You can use this for example after first splitting your part; editing and then joining it together again. Please note that this can’t be run on parts with supports or other attached objects.