@fares.boulamaali The rebuilt surfaces in your examples with the large variation in control point spacing are multi-span surfaces. Your multi-span example surfaces have uniform knots and equal size spans.

Because of the way the NURBS math works in general it is not possible to have uniform control point spacing, uniform knots and equal size spans.

Rebuild uses uniform knot spacing. Non-uniform knots can be useful, particular for curves, but it can also have disadvantages, particularly for free-form surfaces where the “optimum” non-uniform knots may be be very different depending which part of the surface the knots are optimized for. Typically for surfaces uniform knot spacing is a reasonable alternative.

Because Rebuild uses uniform knots the control points spacing will be as shown if the spans are similar size. Again that is a result of NURBS math. For some surfaces It may be possible to find a non-uniform set of knot parameter values which results in a closer correspondence between control point spacing and span That would probably require a fundamentally different rebuild algorithm, which would be likely to be slower for complex surface and produce undesirable results for many free-form surfaces.