Plenoptic Camera Calibration for Multi-Pupil HMD Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The calibration process for head-mounted displays is time-consuming and costly due to the need for evaluating multiple white field images and adjusting each display system to match an external standard, which involves complex and repetitive steps.
Innovation Solution
A plenoptic camera system is used to capture light field information, allowing simultaneous measurement and calibration of multiple user pupil positions through spatially discrete filters, reducing the need for multiple captures and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration process with multiple white field images and neutral density filters is used, then measurement precision is improved, but productivity deteriorates due to time-consuming repetitive steps
Solution Approach 1:
The patent combines multiple calibration measurements into a single light field image capture by using spatially multiplexed neutral density filters positioned at the pupil plane. This allows simultaneous acquisition of multiple white field images at different exposure levels in one shot, eliminating the need for sequential captures and significantly improving calibration speed while maintaining measurement precision.
Solution Approach 2:
The patent transitions from temporal multiplexing (sequential captures) to spatial multiplexing (simultaneous capture) by arranging multiple neutral density filters in different spatial locations at the pupil plane. Each filter captures a different exposure level simultaneously in a single light field image, adding a spatial dimension to the calibration process that eliminates time-consuming sequential operations.
2Measurement precision
If traditional calibration process with multiple captures for different pupil positions is used, then measurement precision is improved, but loss of time worsens due to repetitive adjustment steps
Solution Approach 1:
The patent merges multiple pupil position measurements into a single light field image by utilizing the angular encoding capability of light field cameras. Different pupil positions are captured simultaneously at different angular positions within the same image, eliminating the need for time-consuming mechanical adjustments between captures while maintaining the precision required for accurate calibration.
Solution Approach 2:
The patent performs preliminary spatial encoding of multiple pupil positions within a single light field image capture. The light field camera inherently encodes angular information from different pupil positions in the captured image, allowing all necessary measurements to be obtained in advance without requiring sequential adjustments during the calibration process.
3Productivity
If spatially discrete filters are arrayed across the pupil, then productivity is improved by capturing multiple light properties simultaneously, but device complexity increases
Solution Approach 1:
The patent introduces a relay optical system as an intermediary between the light field camera and the pupil plane. This relay system creates a magnified or demagnified image of the pupil plane at a convenient location, allowing filter arrays to be positioned and addressed more easily while maintaining the spatial multiplexing benefits. The relay optics serve as a mediator that simplifies the physical implementation of the filter array.
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
The plenoptic camera system enables rapid and cost-effective calibration of head-mounted displays by capturing light field images with multiple user perspectives in a single capture, improving calibration speed and reducing operational costs.
Implementation Method 1
A plenoptic camera, which is also referred to as a light field camera, captures information about a light field emanating from a scene. The light field refers to both the intensity of light from the scene and also the direction the light rays are traveling in space.
Implementation Method 2
The optical system for the plenoptic camera features a pupil that is physically accessible for arraying spatially discrete filters across the pupil, enabling multiplexed measurement of different light properties (e.g., luminance, polarization, spectral content) across the pupil.
Data Source
AI summary
A method for measuring performance of a head-mounted display module, the method including arranging the head-mounted display module relative to a plenoptic camera assembly so that an exit pupil of the head-mounted display module coincides with a pupil of the plenoptic camera assembly; emitting light from the head-mounted display module while the head-mounted display module is arranged relative to the plenoptic camera assembly; filtering the light at the exit pupil of the head-mounted display module; acquiring, with the plenoptic camera assembly, one or more light field images projected from the head-mounted display module with the filtered light; and determining information about the performance of the head-mounted display module based on acquired light field image.