How can I plot a velocity field plot with color code?

Hello,

I want to plot the velocity field of my data with color code according to the vector magnitude.

I got my nx1 vectors for x,y,vx,vy which represent x position, y position, x direction velocity and y direction velocity. I am using

figure quiver(x,y,vx,vy);

My question is, should I be using some other function to plot the color coded velocity field or does the function 'quiver' have the feature of color code?

Thanks

Answer 1

[Gautam]

Hello Emre

The “quiver” function in MATLAB does not natively support color coding based on vector magnitude. However, you can achieve this by plotting each vector individually and setting the color according to its magnitude

[x,y] = meshgrid(-pi:pi/8:pi,-pi:pi/8:pi); 
vx = sin(y); 
vy = cos(x); 
magnitude = sqrt(vx.^2 + vy.^2); 
magnitude_normalized = (magnitude - min(magnitude)) ./ (max(magnitude) - min(magnitude)); 
cmap = jet(256); 
figure; 
hold on; 
for i = 1:length(x) 
    for j=1:length(y) 
        % Determine color index 
        color_idx = round(magnitude_normalized(i,j) * (length(cmap) - 1)) + 1; 
        % Plot vector with color 
        quiver(x(i,j), y(i,j), vx(i,j), vy(i,j),1, 'Color', cmap(color_idx, :)); 
    end 
end 
hold off; 
colorbar;
colormap(cmap); 

This produces the following output