Finite Aperture Omni-Directional Camera Model for Depth of Field
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Solution Overview
Problem
Conventional omni-directional stereo rendering lacks depth of field effects, which are important depth cues for immersive virtual reality experiences.
Innovation Solution
A finite aperture omni-directional camera model is introduced, aligning a finite aperture lens and focal point with the omni-directional projection, allowing for depth of field rendering by orienting the lens and focal point in specific directions for spherical and cylindrical projections, and combining this with stereo omni-directional rendering processes to generate photorealistic omni-directional stereo images using light transport rendering algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional omni-directional stereo rendering is used, then the rendering process is simple, but depth of field effects are lost
Solution Approach 1:
The patent changes the camera model parameters from a simple pinhole model to a finite aperture model with explicit lens coordinates and focal points. This parameter change enables depth of field effects by introducing aperture size and focal distance as controllable variables in the rendering process, allowing selective focusing at different depths while maintaining omni-directional capability.
Solution Approach 2:
The patent segments the camera model into distinct components: lens coordinates, focal points, and aperture parameters. By dividing the camera model into these separable elements, the system can independently control depth of field parameters without affecting the overall omni-directional projection structure, thus adding realism while managing complexity.
2Reliability
If a finite aperture lens model is introduced, then depth of field rendering is enabled, but the mapping complexity increases
Solution Approach 1:
The patent inverts the traditional rendering approach by performing inverse mapping from image plane points back to scene points. Instead of projecting scene points to the image plane, the system samples points on the image plane and traces rays backward through the finite aperture lens model, which simplifies the integration of depth of field effects with omni-directional projection by working in the reverse direction.
Solution Approach 2:
The patent introduces an intermediary mapping process that connects image plane coordinates to lens coordinates through focal points. This intermediary step acts as a mediator between the simple image plane sampling and the complex finite aperture geometry, breaking down the complex mapping into manageable stages: image plane point → ray direction → lens point → scene point.
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 solution effectively adds depth of field effects to omni-directional cameras, enhancing the realism and immersion of virtual reality experiences by accurately mapping scene points to camera space and rendering energy contributions, thereby improving the rendering of omni-directional stereo images.
Implementation Method 1
Light transport rendering algorithms such as bidirectional path tracing and photon mapping involve mapping points on an image plane to primary rays in camera space
Implementation Method 2
simulating a presence of at least one light source, or camera, within the space and casting a ray from the light source, or the camera into the space, to a point, p, in the space, possibly after interacting with objects in the second data model, using ray tracing techniques
Data Source
AI summary
In various embodiments, a finite aperture omni-directional camera is modeled by aligning a finite aperture lens and focal point with the omni-directional part of the projection. For example, each point on an image plane maps to a direction in camera space. For a spherical projection, the lens can be orientated along this direction and the focal point is picked along this direction at focal distance from the lens. For a cylindrical projection, the lens can be oriented along the projected direction on the two dimensional (2D) xz-plane, as the projection is not omni-directional in the y direction. The focal point is picked along the (unprojected) direction so its projection on the xz-plane is at focal distance from the lens. The final outgoing ray can be constructed by sampling of point on this oriented lens and shooting a ray from there through the focal point.