Identify local minima in 3D plot/coordinate data

I have some coordinate data, and I am trying to find the points as described on this graph with arrows:

I am trying to find the point in the coordinate data in the 3D plot as it is not always clear when looking at just the vertical plots. I honestly can't get my head around it conceptually what I should do. Does anyone have any ideas on how I should approach this task? I have attached some example data with X,Y,Z position data in columns 1,2,3 respectively.

Answer 1

[Mathieu NOE]

hello

this is what you need :

Find local minima - MATLAB islocalmin - MathWorks France

try this

load('sampledata.mat')

x = sampledata(:,1);
y = sampledata(:,2);
z = sampledata(:,3);

% coordinates of the local minima
TF = islocalmin(z,'MinSeparation',100, 'MinProminence', 5);
xlm = x(TF);
ylm = y(TF);
zlm = z(TF);

plot3(x,y,z)
hold on 
plot3(xlm,ylm,zlm,'r*')

[pkll201]

Thank you, this works great!

[Mathieu NOE]

glad I could help !

have a good day !