AprilTag-Based Resectioning for Surveying Instruments
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Solution Overview
Problem
Current surveying technologies, particularly in construction environments, face inefficiencies and inaccuracies in re-sectioning processes due to reliance on traditional prism targets, which are slow, prone to false positives, and difficult to reorient, especially when occlusions occur.
Innovation Solution
The use of two-dimensional targets like AprilTags, which are cost-effective and accurate, allows for precise positioning and orientation of surveying instruments by enabling automatic detection, reducing false positives, and facilitating faster re-sectioning through machine learning and computer vision algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional prism targets are used for re-sectioning, then the surveying process can be completed, but the process is slow and prone to false positives
Solution Approach 1:
The patent replaces traditional mechanical prism targets with two-dimensional visual targets that can be detected by camera-based computer vision systems. This substitution eliminates the need for optical prisms and enables automated image processing, thereby increasing both speed and reliability of target detection while reducing false positives through algorithmic identification of target features
Solution Approach 2:
The patent changes the fundamental parameter of the target from three-dimensional prism geometry to two-dimensional planar patterns with specific visual characteristics. This parameter change enables the use of image processing algorithms for automatic detection and identification, improving both the speed of detection and accuracy of target recognition while eliminating false positives through feature-based verification
2Ease of operation
If traditional prism targets are used, then positioning can be achieved, but reorientation is difficult especially when occlusions occur
Solution Approach 1:
The patent transitions from three-dimensional prism targets to two-dimensional targets with distinct visual patterns. This dimensional change enables the use of image processing techniques that can detect targets from various angles and partially occluded views, significantly improving ease of operation and detection capability in challenging environments where traditional prisms would be difficult to locate and orient
3Productivity
If two-dimensional targets are used, then re-sectioning speed is improved, but precision positioning and orientation must be maintained
Solution Approach 1:
The patent implements feedback mechanisms through computer vision algorithms that continuously analyze captured images of the two-dimensional targets. The system provides real-time feedback on target detection, position calculation, and orientation determination, allowing for iterative refinement of measurement precision while maintaining high processing speeds through automated feedback loops that correct positioning errors
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
This approach significantly speeds up the re-sectioning process, enhances accuracy, and reduces false positives, providing a robust and efficient method for positioning surveying instruments in construction environments with multi-millimeter precision.
Implementation Method 1
detecting the first target, using a camera of the device, wherein a position and orientation of the first target with respect to the construction environment was previously measured
Implementation Method 2
measuring a distance from the surveying instrument to the first target, using the EDM unit of the surveying instrument
Data Source
AI summary
Two-dimensional targets, such as AprilTags, are used as control points. AprilTags can be used as cost effective alternatives to traditional prism targets without losing accuracy. AprilTags can be placed precisely around a construction site as “permanent” survey control points, like positioning reflector targets. A robotic total station, equipped with a camera sensor, can image the two-dimensional targets to efficiently resection itself.