HMD Transparency Fade Volume for Mixed Reality Occlusion
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Solution Overview
Problem
Mixed and virtual reality head-mounted display (HMD) devices face challenges in accurately rendering holographic objects as the user approaches, causing visual discomfort and occlusion of background objects due to mismatched clip planes and occlusion of the field of view.
Innovation Solution
The implementation of a fade volume with concentrically arranged volumetric shells around the user, where holographic objects transition from full opacity to transparency as they approach the near shell, allowing the background to be visible, using alpha compositing and transparency blend curves for smooth rendering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If holographic objects are rendered with full opacity in mixed reality environments, then the objects are clearly visible and maintain their visual integrity, but the background objects become occluded and users experience visual discomfort when approaching the objects
Solution Approach 1:
The patent dynamically changes the transparency parameter of holographic objects based on their distance from the user. As objects enter the fade volume, their alpha transparency value is adjusted from 0 (fully opaque) to 1 (fully transparent), allowing the background to become visible while maintaining the holographic object's presence in the scene
Solution Approach 2:
The patent introduces an intermediary mechanism (alpha compositing with fade volume) between the holographic object and the background. This intermediary layer smoothly blends the holographic object with the background scene, preventing harsh transitions and reducing visual discomfort while maintaining visibility of both the object and background
2Loss of information
If holographic objects are rendered with full opacity, then the objects maintain their visual integrity and are easily identifiable, but users experience visual discomfort and the field of view is occluded
Solution Approach 1:
The patent changes the visual parameters of holographic objects dynamically based on spatial relationships. When objects are far from the user, they remain opaque for clear visibility. When objects enter the fade volume and approach the user, their transparency parameter is adjusted to prevent occlusion of the field of view and reduce visual discomfort
Solution Approach 2:
The patent implements a dynamic rendering system where the transparency of holographic objects is not static but changes continuously as the user moves or as objects move relative to the user. This dynamic adjustment ensures that the holographic objects adapt to the user's perspective, maintaining visibility while preventing excessive occlusion
Data Source
AI summary
A head mounted display (HMD) device is configured with a sensor package that enables head tracking to determine the device user's proximity to virtual objects in a mixed reality or virtual reality environment. A fade volume including concentrically-arranged volumetric shells is placed around the user including a near shell that is closest to the user, and a far shell that is farthest from the user. When a virtual object is beyond the far shell, the HMD device renders the object with full opacity (i.e., with no transparency). As the user moves towards a virtual object and it intersects the far shell, its opacity begins to fade out with increasing transparency to reveal the background behind it. The transparency of the virtual object increases as the object gets closer to the near shell and the object becomes fully transparent when the near shell reaches it so that the background becomes fully visible.