Sketcher BSplineIncreaseDegree/de: Difference between revisions

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==Beschreibung==
==Beschreibung==


Das Werkzeug [[Image:Sketcher_BSplineIncreaseDegree.svg|24px]] [[Sketcher_BSplineIncreaseDegree/de|Sketcher BSplineGradErhöhen]] Erhöht den Grad (Ordnung) der [[B-Splines|B-Splines]].
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Erhöht den Grad (Ordnung) der B-Spline-Kurve (Siehe die Seite [[B-Splines|B-Splines]] für weitere Informationen über B-splines).
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Revision as of 06:19, 13 May 2024

Sketcher BSplineGradErhöhen

Menüeintrag
Sketch → B-Spline-Werkzeuge → Grad des B-Splines erhöhen
Arbeitsbereich
Sketcher
Standardtastenkürzel
Keiner
Eingeführt in Version
0.17
Siehe auch
Sketcher BSplineGradVerringern

Beschreibung

Das Werkzeug Sketcher BSplineGradErhöhen Erhöht den Grad (Ordnung) der B-Splines.

Anwendung

  1. Eine Kante eines existierenden B-Splines auswählen.
  2. Die Schaltfläche Grad des B-Splines erhöhen drücken.

Example

B-splines are basically a combination of Bézier curves (nicely explained in this and this video).

In this cubic B-spline (degree 3) there are 3 segments, meaning 3 curves are connected at 2 knots.

The degree is indicated by the number in the center. See Show/hide B-spline degree.

B-spline with degree 3 and 2 knots that each have multiplicity 1.

The outer segments each have 2 control points, the inner segment has none to ensure the knots have multiplicity 1. See this page for an explanation about multiplicity.

Increasing the degree to 4 will add control points without changing the shape of the B-spline:

Same B-spline where the degree was changed from 3 to 4. Note that the knot multiplicity has also increased.

From this result you cannot get back to the initial state of the B-spline by decreasing the degree. Some information is lost when the degree of a B-spline is changed. Decreasing the degree back to 3 leads to this:

Same B-spline where the degree was changed back from 4 to 3. Note that the knot multiplicity has increased again. Depending on the B-spline, the algorithm to decrease the degree may add a lot of knots to preserve the shape as has happened here.

Each segment now has 2 control points and each knot is coincident with an additional control point. The knots have C0 continuity so that the B-spline will get "corners" if you move a control point. The information of a higher continuity is therefore lost. See this page for an explanation about continuity.