Polarizing Filter System for Marker-Free Mixed Reality
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Solution Overview
Problem
Existing see-through head-mounted displays (HMDs) obstruct the user's field of view by displaying markers used for calculating attitude changes, which hinders the immersion of mixed reality experiences.
Innovation Solution
A video display system incorporating a marker with a reference pattern, a first polarizing filter, and a second polarizing filter with opposing polarization characteristics, allowing the camera to capture images of the marker without obstruction and calculate attitude changes, enabling seamless mixing of virtual and actual video without marker visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a marker is displayed on the display unit to calculate attitude changes, then attitude calculation accuracy is improved, but the user's field of view is obstructed
Solution Approach 1:
A first polarizing filter is introduced as an intermediary between the marker and the camera, and a second polarizing filter is introduced between the display unit and the user's eye. These polarizing filters act as mediators that allow the camera to capture the marker while preventing the user from seeing it, thus resolving the contradiction between attitude calculation accuracy and field of view obstruction.
Solution Approach 2:
Different polarization characteristics are applied to different parts of the optical path. The first polarizing filter has a specific polarization orientation that allows camera capture, while the second polarizing filter has an orthogonal polarization orientation that blocks user viewing. This local differentiation of optical properties enables simultaneous achievement of accurate marker capture and clean user viewing.
2Reliability
If the marker is made visible for camera capture, then attitude tracking is enabled, but the mixed reality experience is degraded
Solution Approach 1:
The polarizing filters serve as intermediaries that separate the marker visibility for the camera from the user's viewing experience. The first polarizing filter enables the camera to reliably capture the marker for attitude tracking, while the second polarizing filter ensures the user does not see the marker, maintaining immersion in the mixed reality experience.
3Illumination intensity
If the display unit transmits light for see-through display, then actual video visibility is improved, but marker visibility cannot be blocked
Solution Approach 1:
The display unit maintains its light transmission property for actual video, while the second polarizing filter is applied specifically to block the marker light. This local application of polarization filtering allows the display unit to transmit actual video content while selectively blocking marker visibility from the user's perspective.
Solution Approach 2:
The second polarizing filter acts as an intermediary layer between the light-transmissive display unit and the user's eye. It selectively blocks the marker light while allowing the actual video content from the display unit to pass through, thus maintaining both actual video visibility and marker invisibility.
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
Enables users to experience mixed reality without marker obstruction, allowing for accurate attitude calculations and improved immersion by blocking the marker's visibility while capturing its image for attitude adjustments.
Implementation Method 1
a first polarizing filter arranged to correspond to the marker and having a first polarization characteristic, and a second polarizing filter arranged to correspond to the display unit and having a second polarization characteristic contrary to the first polarizing filter
Data Source
Figure 1
Figure 2
Figure 3A~4
AI summary
The video display system (1) includes a marker (3), a first polarizing filter (4), a video display device (2), and an amount-of-change calculation unit (25). The video display device (2) includes a camera (23), a display unit (22), and a second polarizing filter (24). The first polarizing filter (4) is arranged to correspond to the marker (3). The camera (23) captures the marker (3). The second polarizing filter (24) is arranged to correspond to the display unit (22), and has polarization characteristics contrary to the first polarizing filter (4). The amount-of-change calculation unit (25) calculates an amount of change between a first image (MRF) acquired in a first attitude and a second image (MCP) acquired in a second attitude by the camera (23), and calculates an amount of change in attitude of the video display device (2) in accordance with the amount of change between the first image and the second image.