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From: Fivos on 1 Jul 2010 05:03
"Andrew McGillis" <amcgillisREMOVE(a)rogers.com> wrote in message <gkgk19$14g$1(a)fred.mathworks.com>...
> "Gyusok " <gyusok(a)gmail.com> wrote in message <gkgbbq$r0o$1(a)fred.mathworks.com>...
> > Hello,
> >
> > I am Matlab user with little experience. Probably this question is pretty easy for most of you, but I did not find any solution:
> > I have a matrix with n-rows and three columns that represent the 3-dimensional kartesian coordinates of n-surface points obtained by loading a data file.
> > These points I want to visualise as a surface, not just as points in a Figure.
> >
> > The Matrix is as follows:
> > x y z
> > Points = 1.2360 25.4359 38.3812
> > 0.9510 25.4896 36.9742
> > 0.6072 25.5178 35.5796
> > 0.0600 25.5160 33.7439
> > -0.4068 25.4894 32.3855
> > -0.9237 25.4400 31.0457
> > -1.6916 25.3376 29.2938
> > 1.2063 24.6046 37.1182
> > 0.9283 24.7229 35.8329
> > 0.5895 24.8152 34.5606
> > 0.0527 24.9007 32.8865
> > -0.4075 24.9381 31.6487
> > -0.9146 24.9552 30.4301
> > etc....
> >
> > I want to plot the information in the matrix as a surface and not as it is possible using the plot3 command as points. I tried to use the mesh and surf command but did not succed to display a decent visualisation in a figure window.
> >
> >
> > Thank you very much for your help.
> >
> > Gyusok
>
> If your data is not evenly spaced in x and y, you will need to make a mesh, then interpolate it to the mesh using griddata (or JE's gridfit)
>
> You might try:
> % copy-paste from here down------------------
>
> x=Points(:,1);
> y=Points(:,2);
> z=Points(:,3);
>
> dx=1;
> dy=1;
>
> x_edge=[floor(min(x)):dx:ceil(max(x))];
> y_edge=[floor(min(y)):dy:ceil(max(y))];
> [X,Y]=meshgrid(x_edge,y_edge);
> Z=griddata(x,y,z,X,Y);
> % The following line of code is if you use JE's gridfit:
> % Z=gridfit(x,y,z,x_edge,y_edge);
>
> %NOW surf and mesh will work...
>
> surf(X,Y,Z)
> %mesh(X,Y,Z)
>
> %End of code to be copied-----------------------
>
>
> Cheers,
> Andrew

Thanks a ton , this post helped me a lot ! Also note that instead of Z=griddata(x,y,z,X,Y); you can use

F = TriScatteredInterp(x,y,z);
Z= F(X,Y);

which is better according to
http://blogs.mathworks.com/loren/2009/07/22/computational-geometry-in-matlab-r2009a-part-ii/
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