Traffic control by digital imaging cameras - Emerging Trends in Image Processing, Computer Vision, and Pattern Recognition - page 196

6.2 Speed Violation
This part is to determine if the car has crossed a certain speed limit which was chosen to be
600 pixel/s for normal traffic conditions. Two reference points have been defined c 1 = [162 260],
c 2 = [445 504], r 1 = [691 700], and r 2 = [567 577] (as shown in Figure 9 ) . This operation reads the
video frames and first if there was a crossing found in them, it takes the difference which is
the pixel difference between the points. The absolute difference is taken between the referen-
ce defined by ( c 1 and r 1) and the read frame. The difference is defined as start frame, and it
takes another absolute difference between ( c 2, r 2) and the read frame, where the difference is
defined as the final frame.
FIGURE 9 Speed violation.
The difference is made by:
(1)
The time can be known from the following equation where 30 is the frame rate:
(2)
Then the speed is calculated by the following equation, where 310 is the difference in pixels:
(3)