METHOD AND DEVICE FOR MONITORING A SPATIAL VOLUME AS WELL AS CALIBRATION METHOD

• US 20100026786A1
• Filed: 10/24/2007
• Published: 02/04/2010
• Est. Priority Date: 10/25/2006
• Status: Active Grant

• Current Assignee: Vitracom AG (Trilux GmbH & Company KG)
• Original Assignee: Vitracom AG (Trilux GmbH & Company KG)
• Inventors: Link, Norbert
• Granted Patent: US 8,384,768 B2
• Time in Patent Office: Days
• US Class Current: 348/47
• CPC Class Codes: G06T 2207/10012 Stereo images
• CPC Class Codes: G06T 2207/30196 Human being; Person
• CPC Class Codes: G06T 2207/30232 Surveillance
• CPC Class Codes: G06T 7/593 from stereo images
• CPC Class Codes: G06T 7/85 Stereo camera calibration
• CPC Class Codes: G06V 10/147 Details of sensors, e.g. sensor lenses fingerprint or palmprint sensors G06V40/13; vascular sensors G06V40/145; eye sensors G06V40/19
• CPC Class Codes: G06V 20/53 Recognition of crowd images, e.g. recognition of crowd congestion

Abstract

It is customary to produce a three-dimensional image using a camera pair in order to ensure that people are isolated in a lock for separating people and to check that no more than one person at a time passes through the lock for separating people. It is an object of the invention to improve known systems and to accelerate them. To this end, a plurality of camera pairs are used according to the invention, which monitor a spatial volume which is to be monitored from several spatial directions at the same time. To this end, each camera pair monitors the space, determines a height profile and supplements shadowed points in the height profile with data of other camera pairs. Monitoring of a spatial volume, for example a passage lock.

Claims

1. Device for monitoring a spatial volume (10), comprising a plurality of cameras, whereby the cameras are disposed in pairs, with reference to the spatial volume (10) to be monitored, in such a manner that a three-dimensional spatial image can be produced by means of superimposing the camera images (34, 34′

) of a camera pair (11, 11′

), in each instance, wherein at least two camera pairs (11, 11′

) jointly cover a spatial volume (10), in such a manner that at least two three-dimensional spatial images of the same spatial volume (10) can be produced, from different spatial directions.

2. Device according to claim 1, wherein the cameras (11, 11′

) are disposed, in pairs, in the upper region of the spatial volume (10) to be monitored, or above same.

3. Device according claim 1, wherein the spatial volume (10) to be monitored is delimited or enclosed, on at least one side, for example by at least one wall (13) and/or at least one barrier.

4. Device according to claim 1, wherein the sight region (21) of the cameras is oriented in such a manner that the limits of the sight region (21), at least on one side, run parallel to the limitation of the spatial volume (10) to be monitored, at least to a great extent.

5. Device according to claim 1, wherein the sight region (21) of the cameras is oriented in such a manner that the limits of the sight region (21), at least on one side, intersect a spatial limitation that lies opposite the camera pair (11, 11′

), above a head height that can be predetermined.

6. Device according to claim 1, wherein at least one mirror arrangement (14, 14′

) is disposed in the sight field of at least one of the cameras.

7. Device according to claim 6, wherein the cameras are disposed at least approximately horizontally above the spatial volume (10) to be monitored, in such a manner that their longitudinal sides are oriented parallel to the floor surface (15) of the spatial volume (10) to be monitored, at least to a great extent.

8. Device according to claim 1, wherein computer hardware and/or computer software is assigned to the cameras, which is able to digitalize camera data, and to create a height profile of the spatial volume (10) to be monitored, above a reference plane (30), on the basis of these camera data.

9. Device according to claim 1, wherein the device is assigned to a pass-through compartment for persons, in such a manner that persons (12) and/or objects situated within the compartment region can be detected using the cameras.

10. Method for calibrating camera pairs for monitoring a spatial volume (10), comprising the steps of laboratory calibration of the individual cameras, a determination of homographies of reference planes for each camera, and the creation of an epipolar geometry for each camera pair (11, 11′

).

11. Method according to claim 10, wherein within the scope of the laboratory calibration, at least the calibrated focal length, the perspective center, as well as the radial lens distortion of each camera are determined, by means of a square grid disposed perpendicular to the camera, in each instance, as a calibration body.

12. Method according to claim 11, wherein the parameters of the cameras are determined according to the Lenz model.

13. Method according to claim 10, wherein for a determination of at least two homographies, a reference plane (30) as well as an ancillary plane (31), which is preferably parallel to the former, are established in space, whereby height values of one plane point, in each instance, are predetermined by means of a straight line intersection of the sight beams (35, 35′

) of the two cameras of the camera pair (11, 11′

) that penetrate the points, in each instance.

14. Method according to claim 10, wherein an epipolar geometry is produced, whereby the images of the cameras of a camera pair (11, 11′

) are warped onto the reference plane (30).

15. Method according to claim 14, wherein the homologous points of the corresponding camera images (34, 34′

) of a camera pair (11, 11′

) are determined using the standardized cross-correlation function as a measure of similarity.

16. Method according to claim 10, wherein the floor surface (15) of the spatial volume (10) to be monitored is selected as the reference plane (30).

17. Method for monitoring a spatial volume using a plurality of camera pairs (11, 11′

), which view the spatial volume (10) from different spatial directions, and from the camera images (34, 34′

) of which a three-dimensional spatial image can be produced, in each instance, wherein spatial points that cannot be represented, due to shadows cast in the spatial image, in each instance, are supplemented using spatial images of other camera pairs (11, 11′

).

18. Method according to claim 17, wherein the video data streams that come from the individual cameras and/or the camera pairs (11, 11′

) are digitalized.

19. Method according to claim 17, wherein the camera images (34, 34′

) of the individual cameras are corrected on the basis of calibration values.

20. Method according to claim 17, wherein a three-dimensional spatial image of the spatial region that can be seen by a camera pair (11, 11′

), in each instance, is produced for a plurality of camera pairs (11, 11′

), in each instance.

21. Method according to claim 20, wherein as complete as possible a height profile of the spatial volume (10) to be monitored is produced on the basis of the spatial images of a plurality of camera pairs (11, 11′

), wherein the data of different camera pairs (11, 11′

) are joined together to produce a spatial image.

22. Method according to claim 21, wherein the height profile is put into relation with the reference plane (30), wherein the spatial points are calculated using homographies (32, 32′

, 33, 33′

) and straight line intersections in space.

23. Method according to claim 21, wherein the position of the individual spatial points is determined as the center point of a connection distance between the sight beams (35, 35′

) of the two cameras to the spatial point, in each instance.

24. Method according to claim 17, wherein the height profile produced is compared with standard models.

25. Method according to claim 24, wherein after recognition of a standard profile, a check is carried out to determine whether another standard model can be inserted into the remaining space.