@chrisd,

> Is this a case where Sweep and Network Surface overlap in functionality, or is it preferable to use Sweep
> if you don't need more than 2 different guide rails?

There is some overlap between Sweep and Network in some cases like this, but they also do go about constructing the surface in slightly different ways which will have some impact on how the surface is shaped in the middle areas.

See here for some previous discussion:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3081.23
http://moi3d.com/forum/index.php?webtag=MOI&msg=5296.3


> For reverse engineering a bigger question is, if there are curves produced from a 3d
> scan or reference model, which surfacing tools will generate a surface that actually
> passes through the curve?

By default all surfacing tools will make surfaces that pass through the input curves to a tolerance of 0.001 units (for objects with a normal overall bounding box size). The only way you'll get less precise surfaces is if you change some of the options like set profiles mode to "# points" mode and use a low point count for the reconstructed profile count.

- Michael