shrink wrap buildings

Hi,

I'm dealing with a large set of bad quality meshes in an "urban planners" setting.

Many duplicate faces, Inner faces, holes etc.

The source is a "Sketch-up" urban model, that needs to be turned into a watertight model without any "inner" faces.

About 50% of the buildings are simple straight extrusions for which I found a solution.

The other 50% however are of some kind of different shape. So I'm looking for a smart way to approximate them.

My fist idea was to somehow "MRT" the buildings, create a voxel approximation. But the calculation takes quite long and the voxel results in a lot of unnecessary kinks.

So I was thinking of shrink wraping the buildings. There are some expensive algorithms out there which are used in the gaming industry.

QUESTIONS:

- Are there any open source algorithms out there, that do shrink wrapping?

- How does the shrink wrapping algorithm work?

The goal is to make the Sketch-up Data CFD ready.

Thanks in advance for your help

Karl