Hi Andrei - "Exact" does not so much actually mean "exact number of points" - it means "exact shapes". In exact mode profiles are made compatible with one another by knot insertion so that the shape of the loft surface will go exactly through each profile but the end surface inherits the combinations of all point and knot structures of every curve, so usually the final surface will have more points on it than every input curve.

If all the curves are exact copies of one another then they should merge together easily though and you do get the same number of points in the surface in that case.

But because the loft is internally generated as a single big surface before it's split at creases, all pieces of the loft will get "degree elevated" to the highest degree segment, so in this case the arc is degree 2 so the linear areas get degree elevated to degree 2 as well and that's why they have an additional point in those areas.

Also in addition to that when you turn on control points for arc or circle curves what you actually see are not the control points of the exact arc or circle but instead the control points of a rebuilt version of the arc or circle, that's because an exact NURBS circle or arc is itself made up of quadrants that do not deform very well by control point manipulation, so if you edit an arc's control point it automatically switches it into a smooth rebuilt version of it so that it doesn't kind of split apart into 2 arcs divided by some internal point. But in the generated sphere surface you're seeing the direct surface control points in that case. If you pull some of those sphere fragment control points around you'll see some of the splitting apart that I'm referring to, that happens when a surface or a curve has a "fully multiple knot" in it, it sort of means the curve or surface has another kind of internal segmentation in it.

Hope this helps explain some of the additional details.


- Michael