Uncalibrated Camera Vehicle Speed Measurement via Optical Flow
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Solution Overview
Problem
Existing speed enforcement technologies, such as RADAR and LiDAR, face challenges in accurately measuring vehicle speeds in complex road environments, particularly in scenarios where multiple vehicles are moving in different directions.
Innovation Solution
A system and method that utilize digital image processing to measure vehicle speeds by capturing images of calibration and target vehicles, computing optical flow, and applying a parameterized model to determine ground speeds from image speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RADAR or LiDAR is used to measure vehicle speeds, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex electromagnetic measurement systems (RADAR/LiDAR) with a simpler digital image processing system using standard cameras. The mechanical/optical measurement approach is substituted with computational image analysis that tracks vehicle positions across video frames to calculate speeds, thereby reducing device complexity while maintaining measurement capability
Solution Approach 2:
The patent uses digital image copies of vehicles from video frames to measure speed, rather than direct electromagnetic measurement. By creating and analyzing image representations of vehicles across multiple frames, the system achieves speed measurement using simpler camera hardware instead of complex RADAR/LiDAR equipment
2Productivity
If multiple vehicles in different directions are monitored simultaneously, then productivity is improved, but measurement precision deteriorates due to complex road environments
Solution Approach 1:
The patent divides the complex road environment into separate analysis channels by detecting vanishing points for different road directions. Each vanishing point defines a separate region of interest, allowing the system to process and measure multiple vehicles traveling in different directions independently, thereby maintaining measurement precision while increasing overall monitoring capacity
Solution Approach 2:
The patent introduces the dimension of vanishing point geometry to separate and organize multiple vehicle trajectories. By using the spatial relationship of vanishing points and defining regions based on angular sectors from the camera position, the system can simultaneously track vehicles in different directions without cross-interference, resolving the contradiction between monitoring capacity and measurement accuracy
3Measurement precision
If camera calibration is performed to improve measurement precision, then measurement precision is improved, but ease of operation deteriorates due to calibration requirements
Solution Approach 1:
The patent implements self-calibration by automatically detecting vanishing points from the road geometry in captured images and using these detected features to establish the measurement model. The system performs its own calibration by analyzing the natural geometric structure of the road scene, eliminating the need for manual calibration procedures and maintaining high measurement precision through automated geometric constraint extraction
Data Source
AI summary
Measuring speed of a vehicle in a road environment. During calibration, multiple images are captured of a calibration vehicle traveling at a known ground speed. A calibration image feature is located in the image of the calibration vehicle. An optical flow of the calibration image feature is computed to determine a model between an image speed of the calibration image feature and the known ground speed of the calibration vehicle. During speed measurement, multiple images are captured of a target vehicle traveling along a road surface at unknown ground speed. A target image feature may be located in an image of the target vehicle. An image speed may be computed of the target image feature. The model may be applied to determine the ground speed of the target vehicle from the image speed of the target image feature.