Hi Windel,
I understand that you are generating a boundary from a set of 3D coordinates using the “boundary” function in MATLAB, and you are trying to omit the far-off points to get a better-fitting boundary.
To achieve this, you can follow the below steps:
- Calculate the centroid of the given set of points and determine the distance of each coordinate from this centroid.
- Set a threshold distance and create a set of valid coordinates that will be used in the boundary generation.
- Generate the boundary from this set of valid coordinates and keep varying the threshold distance until the desired results.
Here is an example code for the above logic:
%% Example x, y, z coordinates
x = round(rand(20, 1, "double") * 10);
y = round(rand(20, 1, "double") * 10);
z = round(rand(20, 1, "double") * 10);
points = [x y z];
plot3(x, y, z, '.', "MarkerSize", 10);
grid on
hold on
%% Thresholding logic
% Centroid Coordinates and plotting it
centroid = mean(points);
plot3(centroid(1), centroid(2), centroid(3), 'o', "MarkerFaceColor","green")
% Computing valid coordinates
cent_distance = vecnorm(points - centroid, 2, 2); % Distances from centroid
threshold_distance = 5; % Distance Threshold
val_ind = find(cent_distance <= threshold_distance); % Applying threshold
valid_coord = points(val_ind, :); % Valid coordinates
%% Computing boundary from these valid coordinates
k = boundary(valid_coord);
trisurf(k, x, y, z, 'Facecolor', 'red', 'FaceAlpha', 0.1)
Please refer to the below documentations for more information regarding the “vecnorm”, “find”, “boundary” and “trisurf” functions respectively:
- https://in.mathworks.com/help/matlab/ref/vecnorm.html
- https://in.mathworks.com/help/matlab/ref/find.html
- https://in.mathworks.com/help/matlab/ref/boundary.html
- https://in.mathworks.com/help/matlab/ref/trisurf.html
Hope this helps!
Best Regards,
Moksh Aggarwal
