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2D Vector Field Visualization

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2D Vector Field Visualization

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Two functions that create visualizations of 2D vector fields

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Description

The files in this package comprise two Matlab functions that create
visualizations of 2D vector fields.

cquiver renders a vector field as a grid of unit-length arrows. The arrow direction indicates vector field direction, and the color indicates the magnitude. Color is taken from the current colormap.

vfcolor renders a vector field as a grid of colors. Hue indicates the field direction, and saturation indicates the magnitude. The current implementation uses a fixed color coding.

Acknowledgements

Ncquiverref inspired this file.

MATLAB release MATLAB 7.10 (R2010a)
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Comments and Ratings (5)
20 Jun 2014 Nicholas Howe

Fabrizio,
As implemented, cquiver and vfcolor can only display a rectangular grid of vectors. Thus the quiver functionality you are looking for is not available. Sorry! I'll consider whether it can be added in a future version.

20 Jun 2014 fabrizio

Dear Nicholas,
I have a problem with using cquiver and vfcolor. I have a map of vectors that I normally display with quiver by giving it as an imput the x and y position of each vector and the x and y components (say quiver(xcoord, ycoord, xcomp, comp)). Rather then the standard quiver plot, I wish to colorcode this map of vectors. What should I give as an input to vfcolor or cquiver?

11 Sep 2013 Christopher

it works, thank you :)

16 Aug 2013 Nicholas Howe

Christopher,
I guess it's confusing that the usage for cquiver is slightly different from quiver. Sorry about that!

If I understand your example properly, `of` represents the optical flow you wish to display as a 2D array of complex numbers. In that case you should be able to call cquiver like this:

cquiver(of);

16 Aug 2013 Christopher

can you give me an working example of the cquiver() function? i don't know how to handle the input arguments.

formally I used Matlabs quiver() function like this:

%read a single frame of a Video file

im = step(hVideoSrc);

%create a rectangular grid

[X Y] = meshgrid(1:1:size(im, 2), 1:1:size(im, 1));

% compute optical flow for the video
%Horizontal and vertical components in %complex form

of = step(hof,im);

%plot a 2-d vector Field

quiver(X(:),real(of(:)),Y(:),imag(of(:)));

This returns a Quiver Plot of the Optical flow between two frames of the Video.
But when I replace the quiver() function With the cquiver function it just returns me the Colorbar, and nothing else.

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