I'm trying to measure the angle between two needle positions in an analog meter (gauge). such as:
After the image processing of several images, I get the processed image below(a image show different needle positions:
Here, the black dot points were the feature points of needle area, so I use the line fitting algorithm(usually by least square method, or Hough transform to find the line) to get several line positions. I can get the L1, L2, so the angle between those two lines was theta1. But the needle can located in many different places, so I can finally get many positions such as L3, L4...Ln. Those lines should be ideally intersect in one point, which is the rotation center of the needle. I can calculate the equivalent intersection point of all those lines (the red dot), since it is the rotation constraint of the movement.
So, my question is: How can the equivalent point be used to refine the final angle, I mean I want to get a better value of theta1, theta2, theta3....