Interp3 Three-dimensional data interpolation (table lookup) Interp2 Two-dimensional data interpolation (table lookup) See Also interp1 One-dimensional data interpolation (table lookup) For access to the more advanced features, see the on-line help for these M-files and the Spline Toolbox. spline uses these functions in a fairly simple fashion to perform cubic spline interpolation. These routines form a small suite of functions for working with piecewise polynomials. spline uses the functions ppval, mkpp, and unmkpp. Note that this y contains two more values (i.e., two more columns) than does x, hence y(:,1) and y(:,end) are used as endslopes.Īlgorithm A tridiagonal linear system (with, possibly, several right sides) is being solved for the information needed to describe the coefficients of the various cubic polynomials which make up the interpolating spline. Generate the plot of a circle, with the five data points y(:,2).,y(:,6) marked with o's. Uses the cubic spline to extrapolate and predict the population in the year 2000.
![matlab b spline example matlab b spline example](https://media.cheggcdn.com/media%2F760%2F76076764-aa9a-451b-abe9-936223a86bfd%2FphpdZrzLU.png)
Represent the census years from 1900 to 1990 and the corresponding United States population in millions of people. However, if y contains exactly two more values than x has entries, then y(:,1) and y(:,end) are used as the endslopes for the cubic spline. Ordinarily, the `not-a-knot' end conditions are used. Returns the pp-form of the cubic spline interpolant, for later use with ppval (and with functions available in the Spline Toolbox). If xx is a refinement of the mesh x, then yy provides a corresponding refinement of y.
![matlab b spline example matlab b spline example](https://www.mathworks.com/help/examples/matlab/win64/SplineInterpolationOfDistributionAndSpecifyEndpointSlopeExample_01.png)
Returns the value at xx of the interpolating cubic spline. In particular, the given values may be vectors, in which case the spline function describes a curve that passes through the point sequence y(:,1),y(:,2).
Matlab b spline example registration#
I need to apply B-Spline to make my registration more smooth.Spline (MATLAB Function Reference) MATLAB Function Referenceĭescription The spline function constructs a spline function which takes the value y(:,j) at the point x(j), all j. P.S: I am doing image registration (3d MRI), and my control points are my motion fields of registration result.
Matlab b spline example code#
P.S: to run this function, i have control points and ngrid in 3D, E.g from X-Y point of view, my control point( blue) and grid(red) are like this:īased on above notes, s,r and t are distances values between control points and the grid in above picture?Īnybody can help me to find out am I going through the right way and understanding? any alternative way or example code that can help im in 3D Bspline?
![matlab b spline example matlab b spline example](http://matrix.etseq.urv.es/manuals/matlab/toolbox/splines/tutor2b.gif)
If my function is true, how should I call my function now? I dont know how should i calculate r,s and t. The B-Spline is defined by 64 control points (the data values within a 4X4X4 voxel neighborhood), and evaluated inside the unit cube bounded by the eight central voxels, with t, s and r representing distances in the x, y and z direction respectively.īased on above notes I wrote my function in Matlab: function =bspline_matrixform(I,valr,vals,valt,i,j,k) B-Spline in 3D can be extended to produce a scalar function of three parameters: