Aerial Camera Steering Mirror Motion Compensation
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Solution Overview
Problem
Existing aerial camera systems face challenges in capturing high-resolution ground images efficiently due to limitations in speed, altitude, and field of view, which affect productivity and accuracy in photogrammetric solutions.
Innovation Solution
The aerial camera system incorporates a movable field of view that can rotate transversely across the ground, allowing for controlled image capture at defined intervals while reducing the speed of the field of view during image capture, and utilizes a stabilisation assembly with steering mirrors to compensate for motion blur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the survey aircraft travels faster to increase productivity, then more ground area is captured per hour, but motion blur increases and degrades image quality
Solution Approach 1:
The patent implements forward motion compensation by dynamically adjusting the camera's position or orientation during exposure based on the aircraft's motion. The camera system actively compensates for forward movement by moving in the opposite direction, allowing the use of faster shutter speeds that freeze motion blur even at higher aircraft speeds, thus maintaining image quality while increasing productivity
Solution Approach 2:
The system changes the effective exposure parameters by introducing motion compensation mechanisms that allow for shorter exposure times at higher aircraft speeds. By actively managing the camera's motion state through compensation, the system can operate at higher speeds without the traditional penalty of motion blur, effectively changing the relationship between speed and image quality
2Reliability
If images are captured more frequently to improve photogrammetric solution, then overlap between images increases, but the base-to-height ratio decreases affecting accuracy
Solution Approach 1:
The patent introduces across-track scanning that moves the camera's field of view in the transverse direction perpendicular to the flight path. This adds a dimensional element to image capture where images are taken from different lateral positions, creating baselines in the across-track direction that complement the traditional along-track baselines, thereby improving photogrammetric accuracy without requiring increased along-track overlap
3Productivity
If a wider field of view is used to increase productivity, then more ground area is captured, but perspective distortion increases
Solution Approach 1:
The system employs dynamic field of view adjustment where the camera's orientation is actively changed during the scanning process. By moving the camera to capture images from multiple angular positions across the track, the system effectively synthesizes a wider coverage area using multiple narrower FoV images, avoiding the perspective distortion that would result from using a single wide-angle lens
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 enhances productivity by capturing more ground area per hour with reduced motion blur, improving the accuracy of photogrammetric solutions and maintaining high resolution despite increased speed or altitude.
Implementation Method 1
each camera assembly (332) includes a steering mirror (338) arranged to rotate about an axis generally parallel to the direction of motion of the survey aircraft (334)
Implementation Method 2
the steering mirror (338) rotates in synchronization with rotation of the camera tube (18) so as to at least partially compensate for motion blur caused by forward motion of the survey aircraft (334)
Data Source
AI summary
Aerial camera systems are disclosed, including an aerial camera system that comprises at least one camera arranged to capture a plurality of successive images; the at least one camera being rotatable such that the field of view of the camera traverses across a region of the ground that includes multiple different swathes extending in different directions, the at least one camera having a steering mirror to direct light reflected from the ground onto a lens assembly, the lens assembly having a central longitudinal axis extending in a direction generally parallel to a direction of movement of a survey aircraft; and the system arranged to control the at least one camera to capture successive images at defined intervals as the at least one camera rotates.