Fisheye Projector and Spherical Screen for Zero-Distortion Panoramas
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Solution Overview
Problem
Existing virtual reality technologies for small animals, such as mice and rabbits, suffer from limited field of view, significant image distortion, and slow image generation speed, making them unsuitable for detailed brain research.
Innovation Solution
A panoramic presentation method using a fisheye lens and a spherical screen, where the fisheye lens is tangent to the spherical screen and projects a 720° panorama through isometric projection, ensuring zero distortion and rapid image generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple display screens are used to surround small animals to cover their wide field of view, then the field of view coverage is improved, but the device complexity increases and is limited by computer image manipulation capability
Solution Approach 1:
The patent merges multiple display screens into a single spherical screen that surrounds the small animal. This spherical screen integrates the functionality of multiple individual screens while reducing system complexity. The spherical geometry naturally provides 360-degree horizontal coverage, eliminating the need for multiple separate display units and their associated control systems.
Solution Approach 2:
The patent employs a spherical screen with a radius of 11-13 cm positioned around the animal's head. This spherical geometry is specifically chosen to match the animal's wide field of view (220°-230° horizontal) and provides omnidirectional coverage. The curved surface allows for seamless panoramic display without the edges and gaps that would exist with multiple flat screens.
2Area of stationary object
If display screens are arranged horizontally to cover the field of view, then horizontal coverage is improved, but the vertical field of view (especially obliquely above) cannot be satisfied
Solution Approach 1:
The spherical screen extends in all directions from the animal's head position, providing coverage not only horizontally but also vertically including obliquely above positions. The sphere's geometry naturally incorporates vertical angles, allowing visual stimuli to be displayed from any direction including directly above, which is essential for experiments studying vertical visual processing.
Solution Approach 2:
The patent transitions from a two-dimensional horizontal arrangement of screens to a three-dimensional spherical configuration. This adds the vertical dimension to the display capability, enabling coverage of obliquely above field of view while maintaining horizontal coverage. The spherical coordinate system naturally accommodates both horizontal and vertical angular measurements.
3Area of stationary object
If plane images are displayed on multiple display screens around small animals, then the field of view is covered, but the position and shape of objects in three-dimensional space cannot be accurately mapped, causing distortion
Solution Approach 1:
The spherical screen's curved surface matches the natural geometry of visual space around the animal's head. When combined with appropriate projection techniques, this spherical geometry allows for accurate mapping of three-dimensional spatial relationships. The sphere's constant radius ensures that angular measurements are preserved, maintaining accurate position and shape representation of objects in the virtual environment.
4Speed
If the refresh rate of the projector is increased to reduce image delay, then the image generation speed is improved, but the burden of image operation increases significantly
Solution Approach 1:
The patent changes the projection parameter from conventional wide-angle or fisheye lenses to a specific 180° projection angle. This parameter change optimizes the balance between field of view coverage and image generation efficiency. The 180° angle provides sufficient coverage for the animal's field of view while reducing the computational burden compared to attempting to project a full 360° panorama at high refresh rates.
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 method provides 360° horizontal and vertical fields of view with zero distortion, significantly improving image generation speed and maintaining accurate spatial representation, enhancing the suitability of virtual reality for small animal brain research.
Implementation Method 1
a projector projects images on the spherical screen that surrounds the mouse
Implementation Method 2
the projector is equipped with a fisheye lens, the projector is disposed on the spherical screen, and the fisheye lens is tangent to the spherical screen
Implementation Method 3
the viewer is located at the center of sphere of the spherical screen, and the 2D panorama forms a stereoscopic space on the spherical screen
Data Source
Figure 1(a)~2
AI summary
The present invention provides a panoramic presentation method and apparatus. The present invention presents a panoramic image by using a combined structure of a single fisheye projector and a spherical screen in hardware, employs a geometrical relationship between a fisheye lens and the position of a viewer and isometric projection transformation, and enables 180° fisheye projection to present 720° environment information to the viewer in the center of the spherical screen, greatly simplifying the image conversion process and realizing zero distortion. According to a 720° panorama one-step generation method based on a single virtual camera in software, complex steps of collecting six images by a plurality of cameras, synthesizing a cube map and then converting the cube map into a panorama are not needed, the vertex position of a scene is directly adjusted in the process from a 3D space to a 2D image, and a final panorama is generated in one step. The close combination of software and hardware enables an image conversion speed to be increased by more than 6 times, so that the real environment of the content can be displayed, and the viewer may feel immersive and may perform real-time conversion to achieve interaction with the viewer.