HMD Camera Calibration Using a Secondary Display Pattern
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Solution Overview
Problem
Existing camera calibration methods for devices like HMDs are inefficient and disruptive to user experience, requiring noticeable user intervention and consuming significant computational resources.
Innovation Solution
A method for calibrating cameras on devices like HMDs through a lightweight, user-undetectable process involving eye tracking and communication with a secondary device to display a calibration scheme, allowing feature extraction and parameter determination without user interruption, and optionally offloading computational tasks to other devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional camera calibration methods are used, then calibration accuracy can be achieved, but user experience is disrupted and calibration process becomes noticeable to users
Solution Approach 1:
The system performs calibration automatically without requiring user awareness or intervention. The calibration process serves itself by using the display device to present calibration patterns and the camera to capture them, with the processor automatically computing calibration parameters in the background without user involvement.
Solution Approach 2:
The calibration scheme is displayed on the display device before the camera capture occurs. The system prepares the calibration pattern in advance and presents it to the camera, allowing the calibration process to be completed automatically without requiring user action during the actual calibration moment.
2Measurement precision
If comprehensive camera calibration is performed, then calibration accuracy is improved, but computational resources and processing time increase significantly
Solution Approach 1:
The system extracts only the essential calibration information from the display content - specifically the known positions of calibration patterns - and uses this minimal data for computation. By taking out only the necessary geometric information rather than processing entire display frames, the system achieves accurate calibration with reduced computational load.
Solution Approach 2:
The system changes the parameters being processed from complex full-image data to simplified calibration pattern coordinates. By transforming the calibration problem into one involving only discrete known pattern positions rather than continuous image analysis, the computational complexity is significantly reduced while maintaining calibration accuracy.
3Reliability
If calibration is performed frequently to maintain accuracy, then device performance is maintained, but power consumption increases
Solution Approach 1:
The system implements periodic calibration at appropriate intervals rather than continuous calibration. The processor is configured to perform calibration at predetermined time intervals or when performance degradation is detected, rather than continuously, thereby maintaining device performance while reducing overall power consumption.
Solution Approach 2:
The system uses feedback mechanisms to determine when calibration is actually needed. By monitoring device performance and calibration status, the system can trigger recalibration only when necessary, avoiding unnecessary calibration cycles and associated power consumption while ensuring performance maintenance.
Data Source
AI summary
Methods for performing a camera calibration process for outward-facing cameras on devices such as head-mounted display devices are disclosed. Using a second device, a calibration process for the outward-facing cameras on a first device may be performed. Communications of information for a calibration scheme comprising a ground truth comprising features and respective distance separating the features currently displayed or to be displayed may be performed between the first and second device. Calibration parameters may be determined by comparing identified features in captured images of the calibration scheme displayed on the second device to the ground truth.