Fiducial Marker Alignment for Construction Progress Tracking
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Solution Overview
Problem
The construction process of complex structures is prone to errors due to the manual and laborious process of aligning scan images of ongoing construction with computer models, leading to significant re-work, schedule delays, and increased costs.
Innovation Solution
The method involves using fiducial markers in scan images of a 3D physical structure to automate the alignment with a computer model, allowing for the detection of deviations and refinement of alignments using transformation functions and 3D physical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If manual alignment of scan images with computer models is used, then flexibility and adaptability are maintained, but time consumption and labor intensity increase significantly
Solution Approach 1:
Fiducial markers serve as intermediary objects that bridge the scan images and computer model. These markers are placed on the construction site and detected in both the scan images and the virtual model, enabling automatic alignment without complex direct matching algorithms. The markers act as common reference points that simplify the alignment process.
Solution Approach 2:
The fiducial markers are replicated across multiple locations on the construction site, creating multiple reference points for alignment. Virtual copies of these markers are also placed in the computer model at corresponding locations, enabling the system to use multiple correspondence points for robust alignment calculation.
2Measurement precision
If manual alignment processes are used, then system complexity remains low, but measurement precision and detection accuracy deteriorate
Solution Approach 1:
Fiducial markers are pre-placed on the construction site before scanning begins. Their positions are predetermined and known in advance, allowing the alignment process to start immediately with precise reference points rather than requiring time-consuming feature identification and matching during the alignment process.
Solution Approach 2:
The manual mechanical alignment process is replaced with an automated optical and computational system. Instead of manually comparing and adjusting scan images against the computer model, the system uses camera images to detect fiducial markers and automatically calculates transformation parameters through image processing and coordinate transformation algorithms.
3Reliability
If frequent alignment checks are performed to detect errors early, then construction accuracy improves, but productivity and construction speed decrease
Solution Approach 1:
The alignment verification system operates autonomously without requiring manual intervention. The camera automatically captures images, detects fiducial markers, calculates alignment transformations, and compares the construction progress with the computer model. This self-service capability enables frequent checks without adding manual labor time to the construction process.
Solution Approach 2:
The alignment monitoring is performed continuously throughout the construction process rather than as discrete manual checks. As construction progresses and new scan images are captured, the system automatically updates the alignment status, providing continuous verification without interrupting the construction workflow.
Data Source
AI summary
A method for tracking progression of a construction site at different points in time relative to an expected progression of the construction site as represented by a computer model. The method includes generating an image of the construction site by scanning the construction site with an imaging device and detecting a fiducial marker appearing in the image at a location on the construction site. The fiducial marker is unique among fiducial markers positioned on the construction site. The method further includes identifying the detected fiducial marker in association with a unique identifier among the fiducial markers and aligning a coordinate system of the identified fiducial marker with a coordinate system of the computer model, which represents the construction site at points in time.