How to Draw a Spline Curve in AutoCAD Software?

Hello, Friends

Today We will learn Spline Command in AutoCAD Software. 

Command : Spline

Short-cut : Spl

Menu : Draw > Spline

- Draw a Nonuniform Rational B-Spline(NURBS) curve passing through or near a set of fit points / Vertices.

There are two options to draw a Spline : a) Fit b) Control Vertices(CV)

We can draw a spline using many Fit points or many Vertices.

Close(c) : Close Spline curve by joining Last point to Starting point.

Method : Control whether the Spline Curve is created by Fit points or with Control Vertices.

      Fit(f) : Creates a degree 3 (cubic) B-spline by specifying fit points that the spline must pass through.

            Knots(k) : Specify options when we choose Fit Method.

            a) Chord. ( Chord-Length method) Spaces the knots connecting each component curve to be proportional to the distances between each associated pair of fit points. An example is the green curve in the illustration.

            b) Square root. (Centripetal method) Spaces the knots connecting each component curve to be proportional to the square root of the distance between each associated pair of fit points. This method usually produces “gentler” curves.

            c)Uniform. (Equidistant method). Spaces the knots of each component curve to be equal, regardless of the spacing of the fit points. This method often produces curves that overshoot the fit points.

        Control Vertices (CV) :Creates a spline by specifying control vertices. Use this method to create splines of degree 1 (linear), degree 2 (quadratic), degree 3 (cubic), and so on up to degree 10. Adjusting the shape of a spline by moving control vertices often provides better results than moving fit points.

Start Tangency : Specify a Tangent Condition on the starting point of the Spline.

End Tangency : Specify a Tangent Condition on the ending point of the Spline.

toLerance(L): Specifies the distance by which the spline is allowed to deviate from the specified fit points. A tolerance value of 0 requires the resulting spline to pass directly through the fit points. The tolerance value applies to all fit points except the starting and ending fit points, which always have a tolerance of 0.

Object(o): Converts 2D or 3D quadratic or cubic spline-fit polylines to equivalent splines.

Spline Command YouTube Video Link:

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In the next post, we will learn New AutoCAD Command / Topic.

- Bhargav Joshi