Spatio-temporal maps for vehicle detection and tracking

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Solution Overview

Problem

Existing vehicle detection systems, such as inductance loop detectors and computer-vision approaches, face challenges with high maintenance costs, environmental interference, and false alarms due to camera vibration and occlusions, which affect accuracy and reliability in tracking vehicles.

Innovation Solution

A video-based detection system that uses spatio-temporal maps to analyze video data, applying transformation matrices for perspective correction and edge detection techniques to track objects without relying on background data, thereby reducing distortion and improving accuracy in vehicle detection and tracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If inductance loop detectors are used for vehicle detection, then reliable traffic counts can be obtained, but maintenance and installation require lane closures causing significant indirect costs and pavement damage

Engineering Contradiction:
Improvetraffic count reliabilityVSAvoidinstallation ease
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces mechanical inductance loop detectors embedded in pavement with a video-based detection system using cameras and computer vision algorithms. This substitution eliminates the need for physical installation in the roadway, avoiding lane closures and pavement damage while maintaining vehicle detection capability through visual processing of traffic scenes.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system creates a virtual representation of the physical traffic environment by capturing video images and processing them through spatio-temporal maps. Instead of physically interacting with vehicles through inductance loops, the system copies visual information from the scene and processes it digitally to extract vehicle presence, speed, and trajectory data.

Inventive Principle:
Principle #26Copying

2Loss of information

If multiple inductance loop detectors are installed to obtain traffic parameters such as speed and queue lengths, then comprehensive traffic data can be collected, but the cost and complexity of installation and maintenance increase significantly

Engineering Contradiction:
Improvetraffic parameter completenessVSAvoiddetector system complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The video-based detection system performs multiple traffic measurement functions simultaneously using a single camera system. By processing video frames through spatio-temporal maps, the system can extract vehicle presence, speed, trajectory, and queue length information from the same visual data source, eliminating the need for multiple specialized detectors.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system transitions from point-based detection (inductance loops at specific locations) to area-based detection using video frames. By analyzing the two-dimensional video space and temporal sequences, the system can derive multiple traffic parameters from a single observational perspective, reducing the number of detection points needed.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If video cameras are used for vehicle detection, then lower maintenance costs and richer traffic information can be obtained, but environmental factors and occlusions significantly degrade detection accuracy

Engineering Contradiction:
Improvemaintenance costVSAvoiddetection accuracy
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The system performs preliminary background modeling by capturing images during periods when no vehicles are present. This pre-acquired background information is stored and used as a reference for subsequent vehicle detection, allowing the system to distinguish between static background elements and moving vehicles even under varying environmental conditions.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The detection process is segmented into distinct stages: background subtraction to isolate moving objects, edge detection to identify vehicle boundaries, and spatio-temporal map analysis to track vehicle trajectories. This segmentation allows each processing stage to focus on specific features, improving robustness against environmental interference and occlusions.

Inventive Principle:
Principle #1Segmentation

4Reliability

If video-based detection algorithms rely on background frame comparison, then vehicle presence can be detected, but camera vibration causes displacements of static objects and triggers significant false alarms

Engineering Contradiction:
Improvevehicle detection reliabilityVSAvoidfalse alarm rate
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system captures and stores background images during periods when no vehicles are present and when the camera is stable. This pre-acquired background serves as a reference that is insensitive to subsequent camera vibrations, allowing the system to distinguish between actual vehicle movements and apparent movements caused by camera instability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system extracts only the moving components from the video frames by subtracting the static background. By isolating the dynamic elements (vehicles) from the static background, the system eliminates false alarms caused by camera vibration affecting static objects, as only genuine moving objects will show differences from the background model.

Inventive Principle:
Principle #2Taking out (Extraction)

5Loss of information

If computer-vision based approaches are used to detect vehicles, then vehicle information can be extracted from video data, but vehicle occlusions when one vehicle obscures another are difficult to overcome

Engineering Contradiction:
Improvevehicle information completenessVSAvoidocclusion handling complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The system resolves occlusion problems by transitioning from two-dimensional frame analysis to three-dimensional spatio-temporal map analysis. By incorporating the time dimension and tracking vehicle trajectories across multiple frames, the system can infer the presence and position of occluded vehicles based on their motion patterns and trajectory continuity, even when temporarily hidden from view.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The system uses feedback from trajectory tracking to maintain vehicle detection during occlusions. By continuously updating vehicle position estimates based on motion models and previous trajectory information, the system can predict the location of occluded vehicles and restore detection once they become visible again, maintaining information completeness despite temporary obstructions.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS8358808B2Video-based vehicle detection and tracking using spatio-temporal maps
Publication Date: 2013.01.22 UNIV OF WASHINGTON
  • US8358808B2 patent drawing
  • US8358808B2 patent drawing
  • US8358808B2 patent drawing

AI summary

Systems and methods for detecting and tracking objects, such as motor vehicles, within video data. The systems and method analyze video data, for example, to count objects, determine object speeds, and track the path of objects without relying on the detection and identification of background data within the captured video data. The detection system uses one or more scan lines to generate a spatio-temporal map. A spatio-temporal map is a time progression of a slice of video data representing a history of pixel data corresponding to a scan line. The detection system detects objects in the video data based on intersections of lines within the spatio-temporal map. Once the detection system has detected an object, the detection system may record the detection for counting purposes, display an indication of the object in association with the video data, determine the speed of the object, etc.