Moving Camera Surveying with Prism Time-Offset Correction
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Solution Overview
Problem
The challenge of accurately determining the position of a camera mounted on a moving object for three-dimensional data acquisition is exacerbated by unsynchronized clocks between the camera and the surveying apparatus, leading to errors in the calculation of the camera's position.
Innovation Solution
A method and system that adjusts the camera's position calculation by incorporating a correction amount based on the deviation between the measurement time of a fixed reflective prism and the image capture time, using constraint condition expressions and bundle adjustment calculations to synchronize the positions in both local and global coordinate systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the position of the camera is calculated based on the measurement of a reflective prism, then the three-dimensional data can be obtained, but errors occur due to time deviation between measurement and capture
Solution Approach 1:
The patent performs preliminary actions by measuring the position of the reflective prism at multiple time points before and after the image capture time. This allows the system to interpolate or extrapolate the prism's position at the exact moment of capture, compensating for the time deviation between measurement and capture operations.
Solution Approach 2:
The patent implements feedback by using the measured position of the reflective prism to correct and adjust the calculated camera position. The system continuously refines the camera position calculation based on the actual measured position of the prism, creating a feedback loop that reduces errors caused by time synchronization issues.
2Measurement precision
If adjustment calculation is performed to correct time deviation, then the accuracy of three-dimensional data is improved, but the calculation complexity increases
Solution Approach 1:
The patent introduces the reflective prism as an intermediary element to bridge the camera and the surveying apparatus. By measuring the prism's position and using it as a reference point, the system can indirectly determine the camera's position without directly synchronizing the camera's clock with the surveying apparatus, thereby simplifying the overall system architecture.
Solution Approach 2:
The patent changes the parameter approach by transforming the problem from direct time-synchronized position measurement to a position-based correction method. Instead of adjusting for time deviations directly, the system measures spatial positions at different times and uses geometric relationships to calculate the camera's position, converting a temporal problem into a spatial one.
Data Source
Figure 1~2
Figure 3
Figure 4(A)~44(C)
AI summary
The accuracy of three-dimensional data based on images captured by a camera mounted on a moving object is improved. Image data of a captured image captured by a camera 101 that moves while being mounted on a heavy machine 100 is obtained. A total station 200 measures a position of a reflective prism 102 that is a specific part fixed to the camera 101. A position of the camera 101 is calculated based on the measured position of the reflective prism 102. There is a deviation between a time of measurement of the position of the reflective prism 102 and a time of capturing by the camera 101. Adjustment calculation with the position of the camera 101 as an unknown number is performed in the calculation of the position of the camera 101. The adjustment calculation is performed based on the measured position of the reflective prism 101 to which a correction amount corresponding to the deviation between the times is added.