I want to find out how to get the angles between the centroids

3 views (last 30 days)
I have got the code which detects blue colored objects, shows their centroids and draws a line through them. My next task is to display the angle displayed between the centroids. (the angle formed at the elbow joint, with the centroids being located at the shoulder, elbow and wrist. if you could find the code required for this and can explain it a bit it would be helpful.
  1 Comment
Matt J
Matt J on 26 Jan 2023
In what way is displaying the angle a different challenge from what you've already displayed? It's just one more number to add to the image isn't it?

Sign in to comment.

Answers (2)

Askic V
Askic V on 26 Jan 2023
Hello Don,
I think you might find this example useful:
close all
P1 = [231; 84];
P2 = [297; 284];
P3 = [544; 250];
p_12 = P1-P2;
p_23 = P3-P2;
theta = acosd(dot(p_12,p_23)/(norm(p_12)*norm(p_23)))
theta = 100.4253
% Plot results
text(P1(1),P1(2),[' \leftarrow ', num2str(P1(1)),', ', num2str(P1(2))]);
hold on
text(P2(1),P2(2),[' \leftarrow ', num2str(P2(1)),', ', num2str(P2(2))])
text(P3(1),P3(2),[' \leftarrow ', num2str(P3(1)),', ', num2str(P3(2))])
v1 = quiver(P2(1),P2(2), -abs(P2(1)-P1(1)), -abs(P2(2)-P1(2)),'off');
v2 = quiver(P2(1),P2(2), abs(P3(1)-P2(1)), -abs(P3(2)-P2(2)),'off');
grid on
xlim([0 700])
ylim([0 300])

Image Analyst
Image Analyst on 26 Jan 2023
Try title or text on the image axes:
caption = sprintf('Angle = %.2f degrees', theta);
title(caption, 'FontSize', 16);
text(350, 175, caption, 'Color', 'r', 'FontSize', 16);




Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by