Static Distortion Correction for Head Mounted Displays
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Solution Overview
Problem
Head mounted displays (HMDs) face challenges with visual distortions due to the phenomenon of 'pupil swim,' where images appear warped as the user's eyes move, primarily due to the misalignment of the pupil with the eyeball's rotation center.
Innovation Solution
A method for static distortion correction in HMDs involves collecting distortion data for various gaze directions, generating distortion maps for each direction, combining these maps to compute a single multi-view distortion map using weighted averages, and applying this map to the display content for static distortion correction across the entire field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dynamic distortion correction using eye-tracking systems is implemented, then visual distortion is reduced, but device complexity, weight, and power consumption increase
Solution Approach 1:
The patent pre-calculates and stores distortion correction maps for multiple gaze directions before use. During operation, the system simply selects the appropriate pre-computed map based on detected gaze direction, avoiding the need for complex real-time dynamic correction algorithms and eye-tracking hardware.
Solution Approach 2:
The patent changes the approach from dynamic parameter adjustment to static parameter selection. Instead of continuously adjusting distortion correction parameters based on real-time eye position, the system selects from a discrete set of pre-computed correction maps corresponding to different gaze directions, simplifying the control mechanism.
2Reliability
If eye-tracking systems are integrated for real-time distortion correction, then pupil swim is mitigated, but weight and power consumption increase
Solution Approach 1:
The patent extracts and removes the eye-tracking hardware component from the system while maintaining distortion correction functionality. By using alternative methods to determine gaze direction (such as head tracking or simplified sensors), the system achieves acceptable distortion correction without the weight penalty of full eye-tracking systems.
3Measurement precision
If eye-tracking systems are used for dynamic distortion correction, then visual distortion is reduced, but power consumption increases
Solution Approach 1:
The patent updates distortion correction maps periodically or at discrete gaze direction changes rather than continuously. This reduces the computational load and power consumption compared to continuous real-time adjustment, while still maintaining effective distortion correction for each significant gaze shift.
Data Source
AI summary
Disclosed is a method and a Head Mounted Display (HMD) for static distortion correction. The method involves collecting distortion data from an optical arrangement of the HMD, associated with a plurality of gaze directions defined by relative position of the user's pupil or head to a display screen of the HMD. The distortion data includes display pixel coordinates for display pixels and their corresponding image plane coordinates. A distortion map for each gaze direction is generated, including virtual plane coordinates of the corresponding display pixels derived from the distortion data, which are combined to form a single multi-view distortion map (400), calculated by a weighted average of the virtual plane coordinates across the gaze directions. The multi-view distortion map is applied to display content, ensuring distortion correction across entire field of view of the display screen of the HMD.