Road Surface Crack Detection With Shadow Direction Screening
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Solution Overview
Problem
Existing road deterioration diagnosis systems that use image analysis to detect cracks are prone to erroneous detection due to shadows of structures, and these systems often require expensive laser scanners for accurate shadow location determination, making them costly and difficult to maintain.
Innovation Solution
A road deterioration diagnosing device that acquires images of road surfaces along with date, location, time, and capture direction, calculates the direction in which a shadow may be formed using this information, and determines the possibility of erroneous detection by comparing the direction of road surface deterioration with the calculated shadow direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser scanner is used to specify shadow location in the image, then the accuracy of shadow detection is improved, but the system cost and complexity increase
Solution Approach 1:
The patent extracts only the necessary information (shadow direction) from the complex laser scanning process. Instead of using a full laser scanner to map all shadow locations, the system calculates shadow direction based on sun position and road gradient, obtaining the essential information with much simpler means.
Solution Approach 2:
The patent creates a simplified computational model that copies the shadow formation mechanism. By calculating shadow direction from sun position and road geometry rather than physically scanning with laser, the system replicates the shadow detection capability in a computationally efficient manner.
2Measurement precision
If a laser scanner is used to specify shadow location in the image, then the accuracy of shadow detection is improved, but the maintenance difficulty increases
Solution Approach 1:
The system performs self-service by automatically calculating shadow direction using readily available data (sun position, road gradient from the image itself). This eliminates the need for external laser scanning equipment that would require specialized maintenance, making the system more self-sufficient and easier to maintain.
Solution Approach 2:
The patent replaces the mechanical laser scanning system with a computational approach. Instead of physical laser devices that require calibration and maintenance, the system uses mathematical calculations based on astronomical data and image analysis, which are much easier to maintain.
3Productivity
If image analysis is used to detect cracks, then the detection capability is provided, but erroneous detection of shadows as cracks occurs
Solution Approach 1:
The patent introduces shadow direction calculation as an intermediary step between image capture and crack detection. By first determining where shadows are likely to fall based on sun position and road geometry, the system creates a reference framework that helps distinguish actual cracks from shadow artifacts during analysis.
Solution Approach 2:
The system performs preliminary action by calculating shadow directions before conducting crack detection. This advance preparation of shadow location information allows the crack detection algorithm to differentiate between actual road cracks and shadow patterns, reducing erroneous detections.
Data Source
AI summary
A road deterioration diagnosing device acquires an image capturing a road and a date and a time when the image was captured as well as a location and a direction in which the image was captured, detects deterioration of the road surface shown in the acquired image, calculates a direction in which a shadow of a building may be formed over the road surface shown in the image using the date, the time, the location, and the direction, and determines a possibility of erroneous detection of the deterioration on the basis of the direction in which the road surface deteriorates and the direction in which the shadow may be formed.