Augmented Image Registration Using Sensor Pole Optical Targets
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Solution Overview
Problem
Existing digital imaging technologies face challenges in accurately generating augmented images that overlay virtual data onto real-world visuals, particularly in environments with limited or no distinctive landmarks, due to difficulties in precise camera positioning and orientation relative to the site reference frame.
Innovation Solution
The method involves using a digital camera and a position and orientation sensor unit to capture visual images, identify optical targets, calculate camera position and orientation, and generate augmented images by superimposing graphical representations from digital models onto the visual images, leveraging integrated systems like total stations and GNSS antennas for precise measurement and calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If indirect tracking with stationary cameras is used to track mobile cameras, then occlusion problems are reduced, but tracking accuracy deteriorates due to error accumulation
Solution Approach 1:
The patent introduces an optical target as an intermediary element that is tracked by both the stationary camera and the mobile camera. This intermediary provides a common reference point that enables indirect tracking while allowing for error correction through comparison of the two tracking systems, thus maintaining accuracy while reducing occlusion problems.
Solution Approach 2:
The patent employs feedback mechanisms by using known reference points that are visible to both tracking systems. The discrepancies between the stationary camera's track and the mobile camera's track are used to correct errors in the indirect tracking system, continuously refining the accuracy of position and orientation data.
2Measurement precision
If camera position and orientation are calculated relative to site reference frame, then augmented image registration accuracy is improved, but system complexity increases due to multiple coordinate transformations
Solution Approach 1:
The patent segments the coordinate transformation process into distinct stages: first calculating camera position and orientation relative to the position and orientation sensor unit, then transforming to the site reference frame using measured data from total stations or GNSS. This segmentation makes the complex transformation manageable and allows each stage to be optimized independently.
Solution Approach 2:
The position and orientation sensor unit serves as an intermediary coordinate system that bridges the camera and the site reference frame. By introducing this intermediate reference frame with known measurements from external systems, the patent simplifies the overall transformation chain while maintaining high registration accuracy.
3Measurement precision
If optical targets and sensor units are integrated, then measurement precision is improved, but ease of operation deteriorates due to precise alignment requirements
Solution Approach 1:
The patent applies preliminary action by pre-measuring and storing the position and orientation of the sensor unit relative to the site reference frame using total stations or GNSS before camera operations. The optical target is pre-configured on the sensor unit with known geometric characteristics. This preliminary setup eliminates the need for real-time alignment during field operations, maintaining precision while improving ease of operation.
Data Source
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AI summary
An augmented image is generated by capturing a visual image of a site with a digital camera, generating a virtual image or associated information from a digital model of the site, and superimposing the virtual image or associated information on the visual image. To register the digital model with the visual image, a sensor pole is introduced into the field of view, and a combined visual image of the site and an optical target on the sensor pole is captured. The position and orientation of the sensor pole with respect to the site reference frame are measured by sensors mounted on the sensor pole; the position and orientation of the digital camera with respect to the sensor pole are calculated from image analysis of the optical target on the sensor pole; and the position and orientation of the digital camera with respect to the site reference frame are calculated.