I would like to calculate the angle between any two points in an image in MATLAB. What I wish to do is to select a point and then create a vector by dragging the cursor till a centre point (intersection point) from which the pointer will be dragged to the second point? When is the mouse pointer released the angle between the vectors needs to be displayed? Can you please suggest how should I go about in MATLAB.
Any help will be really appreciated.
Regards Parth
Dear Parth,
Ginput command you can use with cursor to select points on the image. further, use the input command to determine the angle between the lines. ie. select three points such that they make a triangle acting as vertices of triangle, thereafter line joining between the vertices can be determined by straight line equations. calculate the angle subtended by the line with x-axis from its slope and then calculate the angle between two lines using trigonometric rule of tan(theta2-theta1) =m1-m2/(1-m1*m2)...where m1 and m2 are slope of the lines connecting the vertices of triangle.
I hope this may solve your problem
with regards,
Prasoon
It would be 3 points only but one point would actually at the intersection of vectors. As in that would be the reference
if its just 2 vectors a=a1 i +a2 j and b=b1 i + b2 j then the angle between them is given by the dot product formula i.e. cos theta=a.b/(||a||||b||) where a.b=a1b1+a2+b2 and ||a||= sqrt(a1^2+a2^2).
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