data = xlsread('signal.xlsx','1');
% Extract the time and signal columns
t = data(:, 1);
signal = data(:, 2);
dt = t(3) - t(2); % sampling time
fs = 1/dt; % freq
wname = 'bior6.8';
N = length(signal);
tv = (0:N-1)/fs;
% Compute the CWT coefficients
scales = 1:200;
C = cwt(signal,scales,wname);
% Create a meshgrid fot the time and scales
[T,S] = meshgrid(tv,scales);
% Plot the CWT coefficients with time and scales
figure;
hS=surf(T,S,abs(C),'EdgeColor','none');
% leave in 3D view for now for demo purposes
%view(0,90); % Set the view to 2D
xlabel('Time (sec)');
ylabel('Scale');
xlim([0, T(end)]);
grid off
colormap (pink(240));
set(gca,'fontname','Times New Roman','FontSize',10)
hold on
SCA = 60;
% left following in temporarily for demo purposes...
plot(xlim,[1 1]*(SCA),'-r','LineWidth',2)
Illustrates the problem/issue; a 2D line parallel to the x axis with its z height equal to 0 is obscured by the surface and the color map chosen is dark enough to prevent the line from showing through. Making the surface less opaque lets one see where the line is located, but it took going to such a low value for .FaceAlpha that the surface itself is then difficult to see for the lighter shades.
So, how to fix? The problem is one needs to draw the line at or above the surface in the 3D axes space even though the desired presentation is from the Z axis direction directly towards the x,y plane. Hence, yline or its workalikes aren't the correct tool for the job, we need plot3 instead.
Z=max(abs(C),[],'all'); % max Z so can be at or above any point in surface
hL3=plot3(xlim,[SCA SCA],[Z Z],'g-','linewidth',2);
pause(10) % for demonstration -- remove when going to final use
view(0,90); % Set the view to 2D after seeing original for a while
I left in the initial line on the Z==0 plane and commented on it and later...to illustrate, the above code as is will show the surface and then the red line in 3D view and add the green line at Z==max(C), then pause for 10 seeconds so can see the result before then switch the viewpoint to the 2D plane view at which time the green line will appear on top and obscure the red line. Remove those extra pieces to use "in anger", obviously.
Sorry it took me so long to think of the cause of the problem after which the solution is obvious...
