matlab griddata插值太慢,关于matlab中用griddata绘制伪色彩图的一点经验教训

griddata

Interpolates scattered data – generally to produce gridded data

Vq = griddata(X,Y,V,Xq,Yq) fits a surface of the form V = F(X,Y) to the

scattered data in (X, Y, V). The coordinates of the data points are

defined by the vectors (X,Y) and V defines the corresponding values.

griddata interpolates the surface F at the query points (Xq,Yq) and

returns the values in Vq. The query points (Xq, Yq) generally represent

a grid obtained from NDGRID or MESHGRID, hence the name griddata.

Vq = griddata(X,Y,Z,V,Xq,Yq,Zq) fits a hyper-surface of the form

V = F(X,Y,Z) to the scattered data in (X, Y, Z, V). The coordinates of

the data points are defined by the vectors (X,Y,Z) and V defines the

corresponding values. griddata interpolates the surface F at the query

points (Xq,Yq,Zq) and returns the values in Vq.

Vq = griddata(X,Y,V, xq, yq) where xq is a row vector and yq is a

column vector, expands (xq, yq) via [Xq, Yq] = meshgrid(xq,yq).

[Xq, Yq, Vq] = griddata(X,Y,V, xq, yq) returns the grid coordinates

arrays in addition.

Note: The syntax for implicit meshgrid expansion of (xq, yq) will be

removed in a future release.

griddata(…, METHOD) where METHOD is one of

‘nearest’  – Nearest neighbor interpolation

‘linear’    – Linear interpolation (default)

‘natural’  – Natural neighbor interpolation

‘cubic’    – Cubic interpolation (2D only)

‘v4’        – MATLAB 4 griddata method (2D only)

defines the interpolation method. The ‘nearest’ and ‘linear’ methods

have discontinuities in the zero-th and first derivatives respectively,

while the ‘cubic’ and ‘v4’ methods produce smooth surfaces.  All the

methods except ‘v4’ are based on a Delaunay triangulation of the data.

Example 1:

% Interpolate a 2D scattered data set over a uniform grid

x = 4*rand(100,1)-2; y = 8*rand(100,1)-4; z = x.*exp(-x.^2-y.^2);

[xq,yq] = meshgrid(-2:.2:2, -4:.4:4);

zq = griddata(x,y,z,xq,yq);

mesh(xq,yq,zq), hold on, plot3(x,y,z,’o’), hold off

Example 2:

% Interpolate a 3D data set over a grid in the x-y (z=0) plane

x = 2*rand(5000,1)-1;

y = 2*rand(5000,1)-1;

z = 2*rand(5000,1)-1;

v = x.^2 + y.^2 + z.^2;

d = -0.8:0.05:0.8;

[xq,yq,zq] = meshgrid(d,d,0);

vq = griddata(x,y,z,v,xq,yq,zq);

surf(xq,yq,vq);