'linear' Linear interpolation (default) 双线性插值

'cubic' Cubic interpolation 双三次插值

'natural' Natural neighbor interpolation  自然邻近插值

'nearest' Nearest neighbor interpolation 最近邻近插值

'v4' MATLAB® 4 griddata method 由MATLAB提供的插值方法

matlab的官方帮助里并没有说明v4所采用的方法，google后得到如下的网友解释：

'v4' is apparently a Greens' function approach. It uses a full matrix composed of ALL of the interpoint distances. This will be SLOW for many points, and extremely memory intensive.

The 'v4' method is much like a radial basis function interpolant. These methods are distance based methods, so you will have a single radially symmetric basis function around EVERY data point. The 'v4' method will form a linear combination of these basis functions, so it must formulate and solve a linear system of equations, of size the number of data points.

参考: http://www.mathworks.co.kr/matlabcentral/newsreader/view_thread/250451

参考: http://www.mathworks.co.kr/matlabcentral/newsreader/view_thread/250451。'natural' Natural neighbor interpolation 自然邻近插值。'nearest' Nearest neighbor interpolation 最近邻近插值。'v4' MATLAB® 4 griddata method 由MATLAB提供的插值方法。'cubic' Cubic interpolation 双三次插值。