Extracting profiles from a point cloud surface along the mazimum dip of the plane

Dear all,

Based on the result of this code (blue cloud rotated), I need to extract a series of profiles (with a fixed diastance) to get the Z values of all the points constituting the profile. These profiles should be extracted from vertical planes oriented according to the maximum slope of the cloud.

Thanks in advance!!

you have other ideas, they are accepted!!  I have included a sketch of what I would like.
clear all
close all
clc
 
load('XYZ');
 
X = XYZ(:,1);
Y = XYZ(:,2);
Z = XYZ(:,3);
 
xyz0=mean(XYZ,1);
A=XYZ-xyz0; % center the data at zero
 
% Find the direction of most variance using SVD and rotate the data to make 
% that the x-axis
 
[~,~,V]=svd(A,0);
a=cross(V(:,3),[0;0;1]);
T=makehgtform('axisrotate', a, -atan2(norm(a),V(3,3)));
R=T(1:3,1:3);
A_rot = A*R;
A_rot = A_rot + [xyz0(1) xyz0(2) 0]; % move so the centers are aligned in z-diection
 
% Plot the raw data
close all
scatter3(X,Y,Z,0.1,"magenta") 
hold on
scatter3(A_rot(:,1),A_rot(:,2),A_rot(:,3),0.1,'blue'); 
xlabel('X-Axis','FontSize',14,'FontWeight','bold')
ylabel('Y-Axis','FontSize',14,'FontWeight','bold')
zlabel('Z-Axis','FontSize',14,'FontWeight','bold')
axis equal

[Umar]

Hi Elisa,

To achieve the extraction of profiles from the rotated 3D point cloud, I had to follow a series of steps after rotating the data to align with the maximum slope direction. Here's an updated version of the code that includes the extraction of profiles.

load('XYZ');

X = XYZ(:,1);

Y = XYZ(:,2);

Z = XYZ(:,3);

xyz0 = mean(XYZ,1);

A = XYZ - xyz0; % Center the data at zero

% Find the direction of most variance using SVD and rotate the data to make that the x-axis

[~, ~, V] = svd(A, 0);

a = cross(V(:,3), [0;0;1]);

T = makehgtform('axisrotate', a, -atan2(norm(a), V(3,3)));

R = T(1:3,1:3);

A_rot = A * R;

A_rot = A_rot + [xyz0(1) xyz0(2) 0]; % Move so the centers are aligned in the z-direction

% Extract profiles along vertical planes oriented based on the maximum slope

% Maximum slope direction

max_slope_direction = V(:,3);

% Fixed distance for profile extraction

fixed_distance = 0.1;

profiles = cell(1, size(A_rot, 1));

for i = 1:size(A_rot, 1) profile_points = A_rot(i, :); profile_points = repmat(profile_points, size(A_rot, 1), 1); distances = sqrt(sum((A_rot - profile_points).^2, 2)); [~, sorted_indices] = sort(distances); profile = A_rot(sorted_indices(2:end), :); % Exclude the point itself profiles{i} = profile; end

% Plot the extracted profiles

figure;

hold on;

for i = 1:size(profiles, 2) scatter3(profiles{i}(:,1), profiles{i}(:,2), profiles{i}(:,3), 0.1, 'green'); end

xlabel('X-Axis', 'FontSize', 14, 'FontWeight', 'bold');

ylabel('Y-Axis', 'FontSize', 14, 'FontWeight', 'bold');

zlabel('Z-Axis', 'FontSize', 14, 'FontWeight', 'bold');

axis equal;

So, first I needed to determine the maximum slope direction from the rotated data. Then, iterate through each point in the rotated cloud, extract profiles at a fixed distance, and plot these extracted profiles which makes sure that profiles are extracted along vertical planes oriented according to the maximum slope of the cloud.

I just tried to execute the code utilizing your XYZ.mat file but my MATLAB session kept disconnected. Please see attached.

So, I need your help to execute the code and let me know if this helps resolve your problem. Thanks for your cooperation.

[Elisa]

dear @Umar thank you so much!! i get an error: "At least one END is missing. The statement beginning here does not have a matching end. "

[Umar]

Hi Elisa,

I have updated the code, please execute the code and let me know if this is what you are looking for.

load('XYZ');

X = XYZ(:,1);

Y = XYZ(:,2);

Z = XYZ(:,3);

xyz0=mean(XYZ,1);

A=XYZ-xyz0; % center the data at zero

% Find the direction of most variance using SVD and rotate the data

[~, ~, V] = svd(A, 0);

a = cross(V(:,3), [0;0;1]);

T = makehgtform('axisrotate', a, -atan2(norm(a), V(3,3)));

R = T(1:3, 1:3);

A_rot = A * R;

A_rot = A_rot + [xyz0(1) xyz0(2) 0];

% Determine the slope of the cloud and extract profiles

slope = max(abs(diff(A_rot(:,3))));

fixed_distance = 0.1; % Set the fixed distance for profile extraction

% Extract profiles based on the slope

for i = 1:size(A_rot, 1) if abs(diff(A_rot(i,3))) == slope profile_points = A_rot(i, :);

        % Extract points at fixed distance along the slope

        for j = 1:fixed_distance:slope

            % Calculate the points along the profile

            profile_points = [profile_points; A_rot(i, 1:2) A_rot(i, 3) + j];
        end

        % Process the profile_points data as needed

        disp(profile_points);
    end
end

% Plot the raw data and extracted profiles

close all

scatter3(X, Y, Z, 0.1, "magenta") hold on scatter3(A_rot(:,1), A_rot(:,2), A_rot(:,3), 0.1, 'blue'); xlabel('X-Axis', 'FontSize', 14, 'FontWeight', 'bold') ylabel('Y-Axis', 'FontSize', 14, 'FontWeight', 'bold') zlabel('Z-Axis', 'FontSize', 14, 'FontWeight', 'bold') axis equal