Photogrammetric System with Unidirectional Shutter for Moving Bodies
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Solution Overview
Problem
Conventional photogrammetry techniques using cameras with focal-plane or electronic rolling shutters introduce positional errors in feature points due to differential exposure timing, leading to reduced accuracy in generating stereo models, especially when capturing images from moving objects like UAVs.
Innovation Solution
A photogrammetric system and method that includes a camera with a shutter unit moving unidirectionally across the imaging surface, a capture position measuring unit to track the camera's position, and a photogrammetry data generator to calculate feature point capture positions based on measured capture positions and shutter movement time, eliminating errors and enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a focal-plane shutter or electronic rolling shutter is used to capture images from a moving object, then the image capture process is enabled, but positional errors are introduced in feature points due to differential exposure timing
Solution Approach 1:
The patent applies preliminary action by measuring the capture position of the camera at multiple time points during the exposure process before photogrammetric calculations are performed. These position measurements are then used to calculate the actual capture position for each feature point, correcting the positional errors introduced by the shutter's differential exposure timing.
Solution Approach 2:
The patent changes the parameter of capture position from a single static value to a dynamic value that varies with time and position on the imaging surface. By measuring capture positions at multiple time points and calculating the actual capture position based on the relationship between imaging surface position and capture position, the system compensates for the motion-induced errors.
2Device complexity
If photogrammetric calculations are performed assuming all objects in an image are captured simultaneously, then the calculation process is simplified, but accuracy in generating stereo model is reduced
Solution Approach 1:
The patent performs preliminary measurements of the camera's capture position at multiple time points during the exposure process. These measurements are stored and then used in the photogrammetric calculations to determine the actual capture position for each feature point, enabling accurate stereo model generation without overly complicating the calculation process.
Solution Approach 2:
The patent introduces an intermediary calculation step that determines the actual capture position for each feature point based on the measured capture positions at different time points and the feature point's position on the imaging surface. This intermediary value serves as a correction factor that bridges the simplified calculation approach and the accurate representation of feature point positions.
3Ease of operation
If feature point positions are used directly from images captured with moving shutters, then the photogrammetric process is straightforward, but the accuracy in photogrammetry is reduced
Solution Approach 1:
The patent performs preliminary measurements of the camera's capture position at multiple time points during the exposure process. These measurements are then used to calculate the actual capture position for each feature point, correcting the positional errors while maintaining a relatively straightforward photogrammetric process.
Solution Approach 2:
The patent implements feedback by using the measured capture positions at different time points to calculate and correct the actual capture position for each feature point. This feedback mechanism continuously refines the position accuracy by comparing the assumed simultaneous capture position with the actual time-varying capture position.
Data Source
AI summary
A photogrammetric system includes a camera installed in a movable body and including a shutter unit that moves an exposed portion across an imaging surface from one side to the other side for exposure to capture an image, a measuring device configured to measure a position at which the camera captures the image, and a photogrammetry data generator configured to extract a feature point from the image captured by the camera, calculate a feature point capture position at which the feature point is captured based on a measurement result of the measuring device and a moving time of the exposed portion, and generate photogrammetry data including the feature point capture position.