PTZ Camera Privacy Mask Correction for Lens Axis Misalignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Surveillance cameras with structural misalignment between the rotation axis and lens center face challenges in applying privacy masks correctly, leading to inefficient masking due to mispositioning and size variations, especially in PTZ cameras with asymmetrical structures.
Innovation Solution
A method and device for correcting the position of privacy masks by measuring distances and angles in multiple imaging conditions, calculating errors, and adjusting mask positions based on structural corrections, using gyro and acceleration sensors to align the lens center with the rotation axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mask size is increased to ensure full coverage when the lens center does not coincide with the rotation axis, then privacy protection coverage is improved, but mask efficiency and precision deteriorate due to unnecessary masking of non-sensitive areas
Solution Approach 1:
The patent dynamically adjusts mask parameters (position and size) based on the measured offset between the lens center and rotation axis. By changing the mask parameters according to the actual structural deviation, the system achieves precise masking coverage without requiring an excessively large fixed mask, thus resolving the contradiction between coverage reliability and masking efficiency
Solution Approach 2:
The system measures the actual offset distance between the lens center and rotation axis, then uses this feedback information to correct and optimize the mask position and size. This closed-loop approach ensures the mask is precisely positioned to cover only necessary areas, improving both coverage reliability and masking efficiency
2Device complexity
If the mask position is fixed without correction, then device complexity is reduced, but mask positioning accuracy deteriorates due to structural misalignment between lens center and rotation axis
Solution Approach 1:
The system performs preliminary measurement and correction of the offset between lens center and rotation axis during initialization or calibration phase. This preliminary action stores the offset data for subsequent use, enabling accurate mask positioning without adding complex real-time adjustment mechanisms, thus maintaining device simplicity while improving positioning accuracy
Solution Approach 2:
The patent creates a corrected mask by applying the measured offset correction to the original mask design. This copying approach with correction allows the system to use a simple fixed mask structure while achieving accurate positioning through data correction, resolving the contradiction between device complexity and positioning accuracy
Data Source
AI summary
A method of creating a privacy mask from an image imaged by an imaging device in which a rotation axis of a camera and a center of a lens do not match includes measuring a distance from the camera to an object in a first imaging condition; creating a first mask for the object, and storing the distance together with the first mask; and creating a second mask for the object in a second imaging condition and correcting a position of the second mask using the first mask and the distance, wherein an imaging angle of the camera in the first imaging condition is same as the imaging angle of the camera in the second imaging condition, and wherein a position of the lens in the first imaging condition is reversed around the rotation axis from a position of the lens in the second imaging condition.