CCTV-Based Stream Discharge Measurement Using Image Analysis
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Solution Overview
Problem
Current methods for measuring discharge and flow velocity in small streams are inefficient and inaccurate due to the difficulty in automating water depth and discharge measurements, especially during flooding, which affects flood forecasting and management.
Innovation Solution
A CCTV image-based real-time automatic discharge measurement system that calculates pixel flow velocity from consecutive images, converts it into actual physical flow velocity, and uses this data to calculate real-time discharge, while also applying image distortion correction and filtering techniques to improve accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional water depth measurement devices (ultrasonic, pressure, float meters) are used in small streams during flooding, then water depth data can be collected, but the measurement accuracy deteriorates due to rough water surfaces and rapid outflow
Solution Approach 1:
The patent replaces conventional mechanical and ultrasonic water depth measurement devices with an image processing-based measurement system. The system captures images of the water surface and uses image analysis algorithms to determine water depth, eliminating the need for physical sensors that are disrupted by rough water surfaces during flooding. This substitution enables continuous measurement without mechanical contact with the turbulent water.
Solution Approach 2:
The patent introduces an image processing system as an intermediary between the water depth measurement requirement and the actual measurement. Instead of directly measuring water depth with sensors in the rough water, the system uses images as an intermediate medium to indirectly determine water depth by analyzing the water surface position in captured images, thereby avoiding direct exposure to turbulent water conditions.
2Extent of automation
If discharge measurement is automated using H-ADCPs, then measurement frequency increases, but measurement coverage remains incomplete requiring manual correction
Solution Approach 1:
The patent creates a universal measurement system that can handle both normal and flooding conditions using the same image processing approach. The system measures water depth, flow velocity, and discharge across the entire stream width continuously, replacing the need for multiple specialized devices (H-ADCPs for automated measurement, manual methods for correction) with a single multi-functional system that provides complete measurement coverage.
3Measurement precision
If water depth measurement is performed manually in small streams during flooding, then measurement accuracy can be maintained, but productivity and response time deteriorate
Solution Approach 1:
The patent implements a self-service measurement system where the image processing system automatically performs water depth measurement without human intervention. The system captures images, processes them through algorithms to determine water surface position and calculate water depth, and continuously provides measurements during flooding conditions, eliminating the need for manual field measurements while maintaining both accuracy and high productivity.
Data Source
AI summary
Disclosed is a system for automatically measuring a discharge in real time based on a CCTV image. The system includes: a water depth measurement device filtering water depth data measured by a measurement means with a local linear regression-based bivariate scatterplot smoothing technique through flexible bandwidth application to calculate the water depth of a stream; an image acquisition device acquiring a continuous image of a flow speed measurement side of the stream; an image analysis PC using an image of the image acquisition device to measure the surface flow speed in real time and receiving a measured water depth from the water depth measurement device to measure the discharge in real time with cross-section data; and a discharge calculation and management server for transmitting and displaying a real-time discharge measurement result based on a web.