Tracking camera using a lens that generates both wide-angle and narrow-angle views

• US 6,734,911 B1
• Filed: 09/30/1999
• Issued: 05/11/2004
• Est. Priority Date: 09/30/1999
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Lyons, Damian M.
• Primary Examiner(s): Garber, Wendy R.
• Assistant Examiner(s): MISLEH, JUSTIN P
• Application Number:
  US09/408,787
• Time in Patent Office: 1,685 Days
• Field of Search: 359/725, 359/708, 359/749, 359/750, 359/751, 359/752, 359/753, 348/335, 348/340, 348/342, 348/169, 348/170, 348/171, 348/172, 348/360, 382/103, 396/71, 396/73, 396/74, 396/75, 396/95, 396/359, 396/348, 396/382
• US Class Current: 348/340
• CPC Class Codes: G01S 3/781 Details
• CPC Class Codes: G01S 3/7864 T.V. type tracking systems
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/61 based on recognised objects

Abstract

A tracking system that provides high resolution images and a low tracking dropout rate is disclosed. The system uses a camera equipped with a dual-angle lens (or another dual-angle focusing system) to obtain both a wide-angle image and a narrow-angle image of a scene. The narrow-angle image provides a high resolution view of the scene. If the object being tracked moves out of the field of view of the narrow-angle image, the wide-angle image is used to find the object. The aim of the camera is then adjusted so that the object will once again appear in the narrow-angle image.

Claims

1. A camera, comprising:

an image sensor having a central region, a peripheral region, and an output; and

collinear optics effective to produce, when aimed at a point of a scene, a narrow-angle image of the point and a central area surrounding the point on the central region of the image sensor, and a wide-angle image of an area surrounding the central area on the peripheral region of the image sensor,

wherein the wide-angle image is a non-panoramic image, and wherein the optics includes a lens with a circular central portion and an annular region coinciding, respectively, with the narrow-angle image portion and the wide-angle image portion of the optics.

2. The camera of claim 1, wherein the peripheral region of the image sensor surrounds the central region of the image sensor, and a pixel density of the central region of the image sensor is substantially the same as a pixel density of the peripheral region of the image sensor.

3. An apparatus for optically tracking a subject, the apparatus comprising:

a camera including an image sensor having a first region, a second region, and an output;

optics having a central portion structured to produce a narrow-angle view and having a peripheral portion surrounding the central portion structured to produce a wide-angle view, configured so that when the camera is aimed at a point, the central portion of the optics forms an image of the point and a central area surrounding the point on the first region of the image sensor, and the peripheral portion of the optics forms an image of an area surrounding the central area on the second region of the image sensor;

a movable base upon which the camera is mounted, configured and arranged to aim the camera in response to drive signals applied to at least one input; and

a tracking system that, based on the output of the image sensor, generates drive signals that are provided to the at least one input of the movable base,

wherein, when a desired subject is imaged by the second region of the image sensor, the drive signals generated by the tracking system cause the movable base to aim the camera at the desired subject and wherein the optics includes a lens with a circular central portion and an annular region coinciding, respectively, with the central and peripheral portions of the optics.

4. The apparatus of claim 3, wherein the tracking system processes the output of the image sensor to compensate for image distortion introduced by the peripheral portion of the optics.

5. The apparatus of claim 3, wherein when the desired subject is not imaged at a center of the first region of the image sensor, the drive signals generated by the tracking system cause the movable base to aim the camera at the desired subject.

6. The apparatus of claim 3, wherein the central portion and the peripheral portion of the optics are collinear.

7. The apparatus of claim 3, wherein the second region of the image sensor surrounds the first region of the image sensor, and a pixel density of the first region of the image sensor is substantially the same as a pixel density of the second region of the image sensor.

8. An apparatus for optically tracking a subject, the apparatus comprising:

an image sensor having a first region, a second region, and an output, and

a optical system having a first portion with a narrow-angle view and a second portion with a wide-angle view, configured and arranged so that when the optical system is aimed at a subject, (i) the first portion of the optical system forms an image of the subject on the first region of the image sensor, and (ii) the second portion of the optical system forms an image on the second region of the image sensor;

a movable base upon which the optical system is mounted, configured and arranged to aim the optical system in response to drive signals applied to at least one input; and

a tracking system that, based on the output of the image sensor, generates drive signals that are provided to the at least one input of the movable base,

wherein, when the subject is imaged by the second region of the image sensor, the drive signals generated by the tracking system cause the movable base to aim the optical system at the subject and wherein a pixel density of the first region of the image sensor is substantially the same as a pixel density of the second region of the image sensor.

9. The apparatus of claim 8, wherein the first portion and the second portion of the optical system are collinear.

10. The apparatus of claim 8, wherein the optical system comprises a lens having a first portion with a narrow-angle view and a second portion with a wide-angle view.

11. The apparatus of claim 8, wherein the optical system comprises a mirror having a first portion with a narrow-angle view and a second portion with a wide-angle view.

12. The apparatus of claim 8, wherein the tracking system processes the output of the image sensor to compensate for image distortion introduced by the second portion of the optical system.

13. The apparatus of claim 8, wherein the second region of the image sensor surrounds the first region of the image sensor.

14. The apparatus of claim 8, wherein when the subject is not imaged at a center of the first region of the image sensor, the drive signals generated by the tracking system cause the movable base to aim the optical system at the subject.

15. An apparatus for optically tracking a subject, the apparatus comprising:

a camera with a PTZ base, the camera having a zoom lens and an output, the zoom lens having a first zoom setting with a narrow-angle view and a second zoom setting with a wide-angle view, configured so that an applied zoom signal selects one of the narrow-angle zoom setting and the wide-angle zoom setting, and an applied aiming signal controls an aim of the camera; and

, the zoom lens having a circular central portion and a annular region coinciding, respectively, with the narrow-angle zoom setting and the wide-angle zoom setting

a tracking system that tracks a subject, based on the camera output, when the zoom lens is set to the narrow-angle view,

wherein, if the tracking system loses track of the subject, the tracking system (i) generates a zoom signal to set the zoom lens to the wide-angle view, (ii) locates the position of the subject, based on the camera output, while the zoom lens is set to the wide-angle view, (iii) generates an aiming signal to aim the camera at the located position of the subject, and (iv) generates a zoom signal to return the zoom lens to the narrow-angle view.

16. A camera comprising:

an image sensor having a central region, a peripheral region, and an output; and

collinear optics effective to produce, when aimed at a point of a scene, a narrow-angle image of the point and a central area surrounding the point on the central region of the image sensor, and a wide-angle image of an area surrounding the central area on the peripheral region of the image sensor,

wherein the field of view of the wide-angle image is at least twice as large as the field of view of the narrow-angle image and wherein the optics includes a lens with a circular central portion and an annular region coinciding, respectively, with the narrow-angle image portion and the wide-angle image portion of the optics.

17. The camera of claim 16, wherein the peripheral region of the image sensor surrounds the central region of the image sensor, and a pixel density of the central region of the image sensor is substantially the same as a pixel density of the peripheral region of the image sensor.