Dual Camera Pair Stereoscopic Sensor for Vehicle Height Measurement
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Solution Overview
Problem
Current surveillance systems, particularly in traffic and road toll applications, face challenges in accurately determining vehicle sizes and distinguishing between vehicles and shadows, leading to potential misinterpretations and inaccuracies in height measurements.
Innovation Solution
A stereoscopic sensor system comprising two camera pairs with overlapping coverage areas, allowing for enhanced accuracy in height imaging by capturing and processing images from multiple angles, enabling precise detection of vehicle dimensions and classification, even in complex scenarios like traffic congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single camera pair is used for surveillance, then the device complexity is low, but the measurement precision of vehicle height and position is insufficient
Solution Approach 1:
The surveillance area is divided into multiple zones (first surveillance zone and second surveillance zone) that are monitored by different camera pairs. Each camera pair focuses on specific zones, allowing for higher measurement precision in each zone while distributing the overall system complexity across multiple specialized units rather than requiring one complex all-coverage system.
Solution Approach 2:
The system transitions from a single-plane surveillance approach to a multi-dimensional coverage model by introducing camera pairs positioned at different locations and angles. This creates overlapping surveillance zones that provide multiple viewing dimensions, enabling more accurate height and position measurements through triangulation and comparative analysis.
2Area of stationary object
If camera pairs are positioned far from the monitored area to cover large zones, then the coverage area is large, but the measurement precision decreases
Solution Approach 1:
Instead of using one distant camera pair attempting to cover the entire area, the surveillance zone is segmented into multiple smaller zones, each monitored by a dedicated camera pair positioned optimally for that specific zone. This allows each camera pair to maintain high measurement precision while collectively covering a large overall area.
Solution Approach 2:
Each camera pair is positioned to cover its primary surveillance zone with some excess coverage that creates overlap with adjacent zones. This partial redundancy ensures that critical areas are monitored by multiple camera pairs, maintaining high measurement precision even as the total coverage area expands.
3Reliability
If a single camera pair defines the surveillance zone, then the device complexity is low, but the reliability of vehicle detection is insufficient
Solution Approach 1:
The detection task is segmented across multiple camera pairs, each responsible for specific surveillance zones. This division allows for specialized optimization of each camera pair for its designated zone while collectively achieving high reliability through redundant coverage and cross-validation of detection results across multiple independent units.
Solution Approach 2:
Multiple camera pairs are merged into a coordinated surveillance system where their individual detection results are combined and cross-validated. The overlapping surveillance zones allow the system to merge data from multiple perspectives, significantly improving vehicle detection reliability by eliminating false positives and confirming detections through multiple independent observations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves improved accuracy in detecting vehicle types, such as trucks with trailers, and reduces false height measurements, allowing for reliable volumetric, speed, and distance assessments, while maintaining a compact sensor configuration.
Implementation Method 1
Any object that are located below or above the surveillance plane (such as point of a vehicle upon the road) will have a slightly different position in an image from the first camera than in an image from the second camera of the stereoscopic sensor, this difference is due to the different angles the cameras have in relation to the object.
Data Source
Figure 1a
Figure 1b~1c
Figure 1d~1e
AI summary
The present disclosure relates to a stereoscopic sensor (100, 100_n) comprising: a first camera pair (110) for capturing a first and a second image, said images being processable into a height image, wherein the stereoscopic sensor (100, 100_n) is adapted to monitor and define a main surveillance zone (150) in a surveillance plane (160) at a predetermined distance (D) from the stereoscopic sensor (100, 100_n), said surveillance plane extending in a direction X and a direction Y. The first camera pair (110) defines a first surveillance zone (151) with a primary coverage (155) in a first direction (161) from a projected mounting position (192) of the stereoscopic sensor (100, 100_1 - 100_n) and a secondary coverage (158) in a second direction (162) from the projected mounting position (192), said projected mounting position being defined as a position along the direction X of said surveillance plane (160), wherein the first and second directions (156, 158) are oppositely directed. The stereoscopic sensor (100, 100_n) further comprises a second camera pair (120) for capturing a first and a second image, said images being processable into a height image, wherein the second camera pair (120) defines a second surveillance zone (152) with a primary coverage (156) in the surveillance plane (160) in the second direction (162) from the projected mounting position (192) and a secondary coverage (157) in the first direction (161) from the projected mounting position (192). Moreover, said secondary coverage (157; 158) of the first and the second camera pairs (110, 120) overlap the primary coverage (155; 156) of the other camera pair (110, 120) respectively. The present disclosure also relates to a system comprises a stereoscopic sensor.