How to measure angle of intersection ?

Asked by thineesh Vijayakumar

thineesh Vijayakumar (view profile)

on 9 Apr 2019
Latest activity Commented on by A. Sawas

A. Sawas (view profile)

on 12 Apr 2019
Accepted Answer by A. Sawas

A. Sawas (view profile)

I need to calculate the angle of intersection . Can anyone share the coding ? How to find the angle (red shaded region) ? Thank you. Rik

Rik (view profile)

on 9 Apr 2019
Do you have the locations of the two lines involved? Then you could fit two linear functions and use mathematics to find the angle.
A. Sawas

A. Sawas (view profile)

on 9 Apr 2019
I think you have asked an identical question before "How to measure angle between two lines?".
I reposted the solution below and added some comments. Please comment on the solution if this is not what you are looking for.

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Answer by A. Sawas

A. Sawas (view profile)

on 9 Apr 2019
Edited by A. Sawas

A. Sawas (view profile)

on 9 Apr 2019

Assuming that the two lines are defined by four points P1, P2, P3, and P4 as such, the first line is L1(P1,P2) and the second line L2 (P3,P4) you can find the angle using the following code:
% define the points as [x,y]
P1 = [1,1];
P2 = [5,5];
P3 = [5,2];
P4 = [1,3];
% dx = x1 - x2;
dx1 = P1(1)-P2(1);
dx2 = P3(1)-P4(1);
% dy = y1 - y2;
dy1 = P1(2)-P2(2);
dy2 = P3(2)-P4(2);
% the angle (in degrees) between the lines:
angle = 180 - acosd((dx1*dx2+dy1*dy2)/(sqrt(dx1^2+dx2^2)*sqrt(dy1^2+dy2^2)));
disp(angle);

thineesh Vijayakumar

on 12 Apr 2019
Thank you :)
A. Sawas

A. Sawas (view profile)

on 12 Apr 2019
You are welcome :)