Omnidirectional imaging apparatus

• US 5,760,826 A
• Filed: 05/10/1996
• Issued: 06/02/1998
• Est. Priority Date: 05/10/1996
• Status: Expired due to Term

• Current Assignee: Trustees Of Columbia University In The City Of New York (Columbia University)
• Original Assignee: Trustees Of Columbia University In The City Of New York (Columbia University)
• Inventors: Nayar, Shree K.
• Primary Examiner(s): CHIN, TOMMY P
• Time in patent office: 753 Days
• Field of Search: 348/36, 348/38, 348/143, 348/147, 348/117, 396/351, 396/21, 396/427, 359/859, 359/853, 359/838-884
• US Class Current: 348/36
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
• CPC Class Codes: G06T 3/0062 Panospheric to cylindrical image transformation
• CPC Class Codes: G08B 13/19626 optical details, e.g. lenses, mirrors, multiple lenses G08B13/19628 takes precedence
• CPC Class Codes: G08B 13/19628 of wide angled cameras and camera groups, e.g. omni-directional cameras, fish eye, single units having multiple cameras achieving a wide angle view
• CPC Class Codes: G08B 13/19641 Multiple cameras having overlapping views on a single scene
• CPC Class Codes: H04N 5/2254 Mounting of optical parts, e.g. lenses, shutters, filters or optical parts peculiar to the presence or use of an electronic image sensor
• CPC Class Codes: H04N 5/2259 Means for changing the camera field of view without moving the camera body, e.g. nutating or panning optics or image-sensors picture signal generation using shifting image-sensors H04N5/349; varying magnification, e.g. angle of view for cameras using only optical means G03B
• CPC Class Codes: H04N 5/2628 Alteration of picture size, shape, position or orientation, e.g. zooming, rotation, rolling, perspective, translation
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor

Abstract

The invention disclosed herein is an omnidirectional imaging apparatus for sensing an image of a substantially hemispherical scene from a single viewpoint, including a truncated, convex, substantially paraboloid-shaped reflector positioned to orthographically reflect an image of the substantially hemispherical scene, and an image sensor positioned to receive the orthographically reflected image. Also disclosed herein is an omnidirectional image projection apparatus for projecting an image of a substantially hemispherical scene as viewed from a single viewpoint, including a means for projecting a collimated beam of light modulated with the image, and a truncated convex substantially paraboloid-shaped reflector positioned to orthographically reflect the collimated beam of light modulated with the image, to project the hemispherical scene.

Claims

1. An omnidirectional imaging apparatus for sensing an image of a substantially hemispherical scene from a single viewpoint, comprising:

(a) a truncated convex substantially paraboloid-shaped reflector positioned to orthographically reflect an image of said substantially hemispherical scene, said paraboloidal reflector having a focus coincident with said single viewpoint of said omnidirectional imaging apparatus, including said reflector;

(b) telecentric means, optically coupled to said reflector, for substantially filtering out principal rays of electromagnetic radiation which are not orthographically reflected by said reflector; and

(c) an image sensor positioned to receive said filtered orthographic reflection of said image.

2. An omnidirectional imaging apparatus according to claim 1, wherein said image sensor comprises a charged coupled device image sensor.

3. An omnidirectional imaging apparatus according to claim 1, wherein said image sensor comprises photographic film.

4. An omnidirectional imaging apparatus according to claim 1, wherein said image sensor comprises a video camera.

5. An omnidirectional imaging apparatus according to claim 1, wherein said reflector comprises a substantially paraboloidal mirror having a surface which substantially obeys the equation expressed in cylindrical coordinates ##EQU10## z being an axis of rotation of said surface, r being a radial coordinate, and h being a constant.

6. An omnidirectional imaging apparatus according to claim 1, wherein said reflector has an axis of rotation and comprises a mirror truncated at a plane which is substantially perpendicular to said axis of rotation and which includes said focus of said reflector.

7. An omnidirectional imaging apparatus according to claim 1, wherein said image sensor is positioned along an axis of rotation of said reflector.

8. An omnidirectional imaging apparatus according to claim 1, further comprising a transparent support coupling said reflector and to said image sensor to maintain the relative positions thereof.

9. An omnidirectional imaging apparatus according to claim 1, wherein said image sensor provides an image signal representative of said orthographically reflected image, further comprising an image signal processing apparatus coupled to said image sensor to convert said image signal into image signal data and to map said image signal data into a cartesian-coordinate system.

10. An omnidirectional imaging apparatus according to claim 9, wherein said image signal processing apparatus further includes interpolation means for providing interpolated image data, whereby said interpolated image data and said image signal data are combined to form said digital image.

11. An omnidirectional imaging apparatus according to claim 10, wherein said image processing apparatus further includes means for zooming in on a preselected portion of said digital image to thereby provide an enlarged image of said preselected portion from a predetermined focal distance.

12. An omnidirectional imaging apparatus according to claim 1, further comprising at least one lens optically coupling said image sensor and said reflector and positioned between said image sensor and said reflector.

13. An omnidirectional imaging apparatus according to claim 1, wherein said telecentric means comprises a telecentric lens.

14. An omnidirectional imaging apparatus according to claim 1, wherein said telecentric means comprises a telecentric aperture.

15. An omnidirectional imaging apparatus according to claim 1, further comprising an additional truncated convex substantially paraboloid-shaped reflector positioned to orthographically reflect an image of an additional hemispherical scene from said single viewpoint, said hemispherical scene and said additional hemispherical scene being complementary to one another so that the combination thereof is a substantially spherical scene, and an additional image sensor positioned to receive said orthographic reflection of said image of said additional hemispherical scene.

16. An omnidirectional imaging apparatus according to claim 15, wherein said reflector and said additional reflector are positioned back-to-back, having a common optical axis and a common focus point, and wherein each of said reflectors comprises a mirror truncated at a plane which is substantially perpendicular to said optical axis and which includes said common focus point.

17. An omnidirectional imaging method for sensing an image of a substantially hemispherical scene from a single viewpoint, comprising the steps of:

(a) orthographically reflecting an image of said substantially hemispherical scene on a substantially paraboloid-shaped reflecting surface such that said single viewpoint of said omnidirectional imaging method, including said step of reflecting said scene on said reflecting surface, coincides with a focus point of said reflecting surface;

(b) telecentrically filtering out a substantial portion of any principal rays of electromagnetic radiation which are not part of said orthographic reflection; and

(c) sensing said filtered orthographically reflected image.

18. The method of claim 17, wherein step (b) comprises sensing said substantially orthographically reflected image from a position along an axis of rotation of said reflector.

19. The method of claim 18, further comprising the steps of providing an image signal which is representative of said orthographically reflected image, converting said image signal into image signal data, and mapping said image signal data into a cartesian-coordinate system.

20. The method of claim 19, further comprising the steps of interpolating said image signal data to define approximate values for missing image data, and forming a digital image from said mapped image data and said interpolated image data.

21. The method of claim 20, further comprising the steps of zooming in on a preselected portion of said digital image to thereby obtain an enlarged image of said preselected portion from a predetermined focal distance, interpolating said image data to define approximate values for missing image data, and forming a digital image from said mapped image data and said interpolated image data.

22. The method of claim 18, further comprising the steps of orthographically reflecting an additional image of an additional substantially hemispherical scene, and sensing said additional orthographically reflected image.