PTZ Camera Pose Estimation Using Iterative Image Registration
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Solution Overview
Problem
Existing methods for estimating the pose of PTZ cameras suffer from accumulative errors, especially when cameras are mounted on moving platforms or have limited feedback, leading to degraded tracking quality and potential failure in surveillance systems.
Innovation Solution
An iterative method that uses image registration to calculate the motion of points between frames, recalculates the absolute camera pose, and updates the pose estimation to minimize errors, employing a weighted minimization technique to refine the tilt and zoom estimates, thereby reducing accumulative errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If image motion estimation algorithms are used to calculate camera pose from frame to frame, then the pose can be determined iteratively, but accumulative errors occur leading to degraded tracking quality
Solution Approach 1:
The patent applies feedback by using the estimated pose from previous frames to inform and correct the current frame's pose estimation. The system continuously compares expected image content based on estimated pose with actual image content, using the discrepancy as feedback to refine the pose estimation and prevent error accumulation.
Solution Approach 2:
The patent performs preliminary action by pre-calculating expected image content and pose relationships before final pose determination. The system uses preliminary pose estimates to generate expected visual information, which is then compared with actual observations to correct errors before they accumulate.
2Speed
If feedback from mechanical gears is used to determine camera pose, then real-time pose information is available, but inaccuracies in manufacturing, assembly, and backlash reduce precision
Solution Approach 1:
The patent introduces an intermediary computational model that mediates between the mechanical feedback system and the final pose determination. The visual feedback system acts as an intermediary that translates mechanical movements into pose estimates while compensating for mechanical inaccuracies through image-based verification.
Solution Approach 2:
The patent substitutes the mechanical feedback system with a visual feedback system based on image processing. Instead of relying solely on mechanical gear sensors, the system uses computer vision to detect feature points and calculate pose from image data, replacing the mechanical measurement mechanism with an optical one.
3Adaptability or versatility
If the camera is mounted on a moving platform, then surveillance coverage is expanded, but both position and pose must be determined increasing system complexity
Solution Approach 1:
The patent merges the determination of position and pose into a unified visual feedback system. Instead of treating position and pose as separate measurement problems requiring separate systems, the invention combines them into a single image-based estimation process that simultaneously determines both parameters from visual data.
Data Source
AI summary
Provided is an iterative method of estimating the pose of a moving PTZ camera. The first step is to use an image registration method on a reference image and a current image to calculate a matrix that estimates the motion of sets of points corresponding to the same object in both images. Information about the absolute camera pose, embedded in the matrix obtained in the first step, is used to simultaneously recalculate both the starting positions in the reference image and the motion estimate. The recalculated starting positions and motion estimate are used to determine the pose of the camera in the current image. The current image is taken as a new reference image, a new current image is selected and the process is repeated in order to determine the pose of the camera in the new current image. The entire process is repeated until the camera stops moving.