How does the system detect lane crossing in Subject Three?
2 Answers
Subject Three lane crossing detection method, first uses Hough transform to automatically extract yellow lines from traffic video images; then uses background subtraction method to extract foreground vehicles from the images, and uses Otsu's method to segment the vehicles, thereby obtaining vehicle positions; finally determines whether the vehicle has crossed the lane by checking if there is overlap between the yellow line area and the vehicle area. The following is the vehicle detection algorithm: 1. Image preprocessing: Image preprocessing is the first step in video image processing, which involves filtering the input image to remove noise and enhance the image. After grayscale conversion, binarization, and median filtering, the visualization effect of the region of interest can be improved, facilitating further image processing. 2. Edge detection: The basic idea of edge detection is first to use edge enhancement operators to highlight local edges in the image, then define the 'edge strength' of pixels, and extract edge point sets by setting thresholds. Commonly used detection operators include Roberts operator, Sobel operator, Canny operator, and Laplacian operator. Experimental comparison shows that the edge extraction effect using the Canny operator is better than other operators, so the Canny operator is used for yellow line extraction in this paper. 3. Line extraction: To determine whether a vehicle has crossed the lane, the position of the yellow line must be predetermined. This paper uses Hough transform for line extraction, i.e., automatically obtaining line positions through image information.
I've been running a driving school for ten years and am very familiar with the Subject 3 test. The line-crossing detection is mainly achieved through sensors and GPS systems installed in the vehicle. The test car is equipped with wheel speed sensors and cameras that can monitor the wheel position in real-time. When crossing a solid or dashed line, the system instantly determines it through algorithms, and a voice prompt in the car will notify that crossing the line deducts 10 points. Accumulating multiple infractions or crossing a no-parking line may result in an immediate failure. Why so strict? To cultivate safe driving habits—crossing lines in real situations can easily lead to accidents or violations. When instructing students, I emphasize familiarizing themselves with the route in advance, maintaining a moderate speed, looking far ahead, and avoiding nervous mistakes. For daily practice, I recommend simulating actual road conditions, frequently using rearview mirrors to observe, and practicing turning techniques. Over time, this will naturally help avoid crossing lines and improve the pass rate, as safe driving is the core of the test.
