Tutorial: Put 3D Vector Field data into ParaView

ParaView is open-source software for 3D visualization - but getting data in is non-trivial.

Description

I spent some time working out how to export data from Matlab (specifically a 3D vector field) in a way which could then successfully imported into ParaView (www.paraview.org).
I made this tutorial to summarize the method I found - which I hope others will also find useful.

• Acknowledgements: This submission has inspired the following:; Matlab 3D vectors to Paraview (via binary VTK file)
• MATLAB release: MATLAB 7.10 (2010a)

[Marmago]

I have a problem. How I can describe in matlab matrices bx, by and bz 50x50?
Please, I need to Know soon!! Thnks!!

[Leo Charleston]

Thanks for the tutorial, it worked for me!

[Leo Charleston]

By the way, only IBM machines produces "BigEndian" binary files, all x86 are LittleEndian.

[Paddy]

Could you please show how you calculated your vector field? I calculate a field in Matlab, visualise it with e.g. quiver3 (and looks as expected), but the field looks very different (i.e. wrong) in Paraview after I export it as per your instructions. A simple example of what I am doing is below. I then read the resulting field in as per your instructions, and the resulting plots in paraview aren't correct?

Thanks alot!

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% visualise Taylor-Green vortex
clear all;

% coordinates
x = linspace(0,1,100);
y = linspace(0,1,100);
z = linspace(0,1,100);
[xx,yy,zz] = meshgrid(x,y,z);

% x,y,z components of vector field
u = sin(pi*xx).*cos(pi*yy).*cos(pi*zz);
v = -cos(pi*xx).*sin(pi*yy).*cos(pi*zz);
w = sqrt(2/3).*cos(pi*xx).*cos(pi*yy).*sin(pi*zz);

% write for paraview
V = cat(4,u,v,w);
B = permute(V,[4 1 2 3]);
fid = fopen('V.raw','w');
fwrite(fid,V,'float');
fclose(fid);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

[Daniel Gallichan]

@Paddy - I would suggest you try swapping x and y. Matlab has for me a rather annoying habit of defining x as the *second* coordinate, and y as the first. To get your code to work in Paraview, you should just need to swap x and y in your meshgrid call - or use ndgrid which keeps x as the first coordinate.

[Paddy]

Great, thanks Daniel - works perfectly now.

[W Thielicke]

Great starting point! Thank you!