Omnidirectional Stereo Ranging with Three Fish-Eye Cameras
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Solution Overview
Problem
Existing stereo camera systems require at least three spherical-image cameras to measure distances in all directions, making it difficult to achieve distance measurement with a smaller configuration.
Innovation Solution
An imaging device with three fish-eye cameras arranged on a cubic casing, where each camera has a 180° or more angle of view, is used to capture images in a way that each camera's imageable range does not include the other cameras, allowing for omnidirectional stereo ranging without blind spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two spherical-image cameras are used for distance measurement, then the configuration is simpler, but the cameras capture each other in their image ranges making distance measurement impossible in those directions
Solution Approach 1:
The patent transitions from spherical-image cameras (360-degree coverage) to fish-eye lenses with 180-degree or more angle of view. By arranging three fish-eye cameras on the vertices of a regular tetrahedron, each camera captures images in a specific directional hemisphere. This dimensional arrangement in 3D space allows the system to achieve omnidirectional coverage without cameras capturing each other, resolving the contradiction between simple configuration and measurement reliability.
2Reliability
If three or more spherical-image cameras are used to avoid capturing each other, then distance measurement reliability improves, but the device complexity increases
Solution Approach 1:
The patent employs an asymmetric geometric arrangement by placing three cameras on the vertices of a regular tetrahedron rather than using symmetric spherical cameras. This asymmetric positioning creates specific angular relationships (109.5 degrees between optical axes) that prevent cameras from capturing each other while maintaining omnidirectional coverage. The asymmetric geometry optimizes the field of view overlap and baseline distances for accurate stereo matching, achieving reliable distance measurement with only three cameras.
Solution Approach 2:
The patent changes the angle of view parameter from spherical cameras (360 degrees) to fish-eye lenses (180 degrees or more). This parameter change, combined with the tetrahedral arrangement, allows each camera to cover a hemispherical field of view without including other cameras in the image range. The specific angle of view parameter is optimized to balance coverage area with avoidance of self-capture, enabling reliable distance measurement with minimal camera count.
3Area of stationary object
If fish-eye lenses with 180° or more angle of view are used, then the imaging range is expanded, but the arrangement becomes more complex to avoid capturing other cameras
Solution Approach 1:
The patent segments the omnidirectional imaging space into multiple hemispherical regions, each covered by a single fish-eye camera. By dividing the 360-degree spherical coverage into three overlapping hemispheres from tetrahedral vertices, each camera is responsible for a specific directional sector. This segmentation simplifies the arrangement logic compared to spherical cameras, as each camera's 180-degree field of view naturally defines its coverage zone without requiring complex coordination to avoid capturing other cameras.
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 distance measurement in all directions with a smaller configuration, ensuring comprehensive coverage without the need for additional cameras.
Implementation Method 1
two fish-eye lenses arranged such that incident surfaces of the fish-eye lenses are opposite to each other
Implementation Method 2
cameras are arranged at a plurality of different viewpoints and images are captured
Implementation Method 3
Distances from the cameras to the corresponding points are measured on the basis of the parallax of the corresponding points
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
An imaging device (1a, 1b, 1c, 1d, 1e, 1f) includes at least one imager (Cam0, Cam1, Cam2, Cam3, Cam4, Cam5, Cam6, Cam7) including an imaging element (210, 212) configured to receive light incident through a lens (240); and a casing (10a, 10b, 10c, 10d, 10e, 10f) at which at least four of the imagers are arranged, the casing being configured such that each one of the imagers and another one of the imagers have optical axes substantially parallel to each other and have opposite incident directions of light on the optical axes, and each one of the imagers is arranged outside imageable ranges of the other imagers.