Placing circle on floor of scatter3 plot

I currently have an 11x11x11 scatter array of intensities. I wish to underlay a mock electrode as a flat black circle centered at the origin. Confused on how to display a solid circle on the same plot as this visualization. Thanks!

Answer 1

[Jay Vincelli]

This can also be solved using the patch() function to plot the parametric equation of a circle:

% Create and plot sphere grid
[X,Y,Z] = meshgrid(-2.5:.5:2.5,-2.5:.5:2.5,0:.5:5);
scatter3(X(:),Y(:),Z(:),'filled')

% Create and plot circle
C = [0,0,0];   % Center of circle 
R = 1 ;    % Radius of circle 
theta = 0:0.01:2*pi;
x = C(1)+R*cos(theta);
y = C(2)+R*sin(theta);
z = C(3)+zeros(size(x));

hold on
patch(x,y,z,'k');
hold off
axis equal