Examples are bundled to illustrate various B-spline curve computation and approximation methods. Curve Fitting Toolbox can handle vector-valued splines. 1-9) Describes conventions related to the use of vectors, and the naming of commands. 1-8) Describes the intended audience for this product. The simplest way to get started is to run "bspline_gui", which activates the figure window to place B-spline control points interactively. 1-7) Compares spline approximation using the MATLAB spline command with the capabilities of the Spline Toolbox. It consists of three major steps: (1) NURBS curve fitting for each row.
It is also possible to explicitly set the x, y and z coordinates as well as the weight of a control point: click on the point, enter new values and hit ENTER.Īs regards the non-interactive interface, functions include calculating and drawing basis functions, computing points of a (weighted or unweighted) B-spline curve with de Boor's algorithm, and estimating B-spline control points given noisy data, either with or without parameter values associated with the observed data points.įrom a programmers' perspective, this example illustrates how to use nested functions to extend variable scope, implement drag-and-drop operations, combine normalized and pixel units for control docking and register multiple callbacks for a single event in an interactive user interface. Non-uniform rational B-spline (NURBS) surface fitting from data points is wildly. Control point adjustment works in 3D use the rotation tool to set a different camera position. Hold down the left mouse button over any control point and drag it to another location. < tau(12), a fit with a cubic spline, i.e., a fourth order spline. Once done, control points may be adjusted with drag-and-drop. optimize knots using the optknt and newknt commands from Curve Fitting Toolbox. x0:5 y4 + 3.x - 2.x.2 plot (x,y,'') plot discreet data points In the figure window, use the Tools. The first is accessed by creating a plot in the normal way, and then use the Tools/Basic Fitting menu available in the figure window. The user may terminate adding control points by pressing ENTER or ESC, or may place the last control point with a right mouse button click. There are a couple of tools for interactive curve fitting in MATLAB. As points are placed in the axes, the B-spline of specified order is drawn progressively.
The package comprises of a graphical utility to place uniform B-spline control points and see how the B-spline is redrawn as control points or control point weights are adjusted, and functions to estimate B-splines with known knot vector, given a set of noisy data points either with known or unknown associated parameter values.Īs regards the interactive interface, the user is shown a figure window with axes in which to choose control points of a uniform B-spline.