Method and system for enhanced portal security through stereoscopy

• US 20050093697A1
• Filed: 11/05/2003
• Published: 05/05/2005
• Est. Priority Date: 11/05/2003
• Status: Active Grant

• Current Assignee: Cognex Technology & Investment Corporation (Cognex Corporation), Coonex Technology and Investment Corporation
• Original Assignee: Coonex Technology and Investment Corporation
• Inventors: Nichani, Sanjay, Shatz, David, Fix, Raymond A., Marrion, Cyril C. Jr., Wolff, Robert, Halbrooks, Gene
• Granted Patent: US 7,623,674 B2
• Time in Patent Office: Days
• US Class Current: 340/545.1
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: G06T 7/593 from stereo images
• CPC Class Codes: G06V 20/53 Recognition of crowd images, e.g. recognition of crowd congestion
• CPC Class Codes: G07C 9/00 Individual registration on entry or exit
• CPC Class Codes: G07C 9/15 with arrangements to prevent the passage of more than one individual at a time

Abstract

Enhanced portal security is provided through stereoscopy, including a stereo door sensor for detecting and optionally preventing access violations, such as piggybacking and tailgating. A portal security system can include a 3D imaging system that generates a target volume from plural 2D images of a field of view about a portal; and a processor that detects and tracks people candidates moving through the target volume to detect a portal access event.

Claims

1. A portal security system, comprising:

a 3D imaging system generating a target volume from plural 2D images of a field of view about a portal; and

a processor detecting and tracking people candidates moving through the target volume to detect a portal access event.

3. The portal security system of claim 1 or 2 wherein the target volume is less than the field of view.

5. The portal security system of claim 1, wherein the target volume has a depth less than a depth associated with the field of view.

6. The portal security system of claim 1 wherein the portal access event is a piggyback event.

7. The portal security system of claim 1 wherein the portal access event is a person event that triggers a tailgating event.

8. The portal security system of claim 1 wherein the portal access event is a person event that activates the portal.

9. The portal security system of claim 1 wherein the portal access event is a ambiguous event.

10. The portal security system of claim 1, further comprises:

plural cameras receiving plural 2D images of a field of view about a portal;

a 3D image generator generating a 3D model from the plural 2D images;

a filter providing a target volume from the 3D model;

a people candidate detector detecting people candidates within the target volume; and

a people candidate tracker tracking movement of the people candidates over time to detect portal access events.

11. The portal security system of claim 1 where the portal is a revolving door, a sliding door, a swinging door, or a man trap.

35. The portal security system of claim 1, wherein the processor automatically calibrates a 3D coordinate system that corresponds to a 3D coordinate system of a portal scene.

2. A portal security system, comprising:

a 3D imaging system generating a target volume from plural 2D images of a field of view about a portal; and

a processor dynamically varying the target volume according to a position of the portal, the processor detecting and tracking people candidates moving through the target volume to detect a portal access event.

4. A portal security system, comprising:

a 3D imaging system limiting a field of view about a portal and generating a target volume from plural 2D images of the limited field of view; and

a processor detecting and tracking people candidates moving through the target volume to detect a portal access event.

12. A portal security system, comprising:

a 3D imaging system generating an entry target volume and an exit target volume, the entry target volume being generated from plural 2D images of a field of view about an entry of a portal, the exit target volume being generated from plural 2D images of a field of view about an exit of the portal; and

a processor detecting and tracking people candidates moving through the entry target volume and the exit target volume to detect a portal access event.

13. A method of providing portal security, comprising:

generating a target volume from plural 2D images of a field of view about a portal; and

detecting people candidates within the target volume; and

tracking the people candidates moving through the target volume to detect a portal access event.

15. The method of claim 13 or 14 wherein the target volume is less than the field of view.

17. The method of claim 13, wherein the target volume has a depth less than a depth associated with the field of view.

18. The method of claim 13 wherein the portal access event is a piggyback event.

19. The method of claim 13 wherein the portal access event is a person event that triggers a tailgating event.

20. The method of claim 13 wherein the portal access event is a person event that activates the portal.

21. The method of claim 13 wherein the portal access event is a ambiguous event.

22. The method of claim 13, further comprises:

receiving plural 2D images of a field of view about a portal;

generating a 3D model from the 2D images;

providing a target volume from the 3D model;

detecting people candidates within the target volume; and

tracking movement of the people candidates over time to detect portal access events.

23. The method of claim 13 wherein the portal is a revolving door, a sliding door, a swinging door, or a man trap.

25. The method of claim 13 wherein detecting people candidates comprises:

generating a low resolution representation having a topological profile of the target volume;

identifying a location of a peak within the low resolution representation; and

converting the location of the peak into an approximate location of a people candidate in a high resolution representation of the target volume.

26. The method of claim 13 wherein detecting people candidates comprises:

generating a head template having dimensions corresponding to a height and an approximate location of a people candidate; and

determining a fine location of the people candidate by matching the height of the people candidate to heights within an area of a representation of the target volume, the area corresponding to the dimensions of the head template.

27. The method of claim 26, further comprising:

determining a distribution of heights within the area corresponding to the dimensions of the head template and the fine location of the people candidate; and

discarding the people candidate if the distribution of heights covers less than a height distribution for a head of a person.

28. The method of claim 26, further comprising:

determining plural fine locations for plural people candidates;

comparing the plural fine locations in three dimensional space;

discarding at least one of the plural people candidates having a fine location that overlaps with another fine location of another people candidate.

29. The method of claim 13, wherein tracking the people candidates comprises:

generating confidence scores corresponding to numbers of people candidates being within the target volume; and

detecting the portal access event from a series of the generated confidence scores.

30. The method of claim 29, further comprising generating confidence scores corresponding to at least one person being within the target volume by:

generating a target volume in three dimensional space;

generating individual scores for three dimensional points within the target volume, each of the individual scores corresponding to a height of one of the three dimensional points relative to a height threshold;

generating a cumulative score from the individual scores; and

computing a confidence score corresponding to at least one person being within the target volume based on the cumulative score and a second threshold.

31. The method of claim 29, further comprising generating confidence scores corresponding to only one person being within the target volume by:

generating a target volume in three dimensional space;

removing a portion of the target volume that corresponds to one of the people candidates in the target volume;

generating individual scores for three dimensional points remaining within the target volume, each of the individual scores corresponding to a height of one of the remaining three dimensional points relative to a height threshold;

generating a cumulative score from the individual scores; and

computing a confidence score corresponding to only one person being within the target volume based on the cumulative score and a second threshold.

32. The method of claim 29 further comprising generating confidence scores corresponding to two or more people being within the target volume based on a separation between head locations of the people candidates.

33. The method of claim 29 further comprising generating confidence scores corresponding to two or more people being within the target volume based on a template score generated from matching head templates to head locations of the people candidates.

34. The method of claim 13 wherein tracking the people candidates further comprises:

generating a set of traces over a sequence of frames, each trace in the set corresponding to a trajectory of a people candidate during the sequence of frames;

assigning weights to the sequence of frames, such that the weights are a uniform weight unless the set of traces includes a first trace and a second trace with the second trace being generated over a set of frames that is substantially less than the first trace, the weights assigned to the set of frames that generated the second trace being assigned a weight less than the uniform weight; and

applying the assigned weights of the sequence of frames to the confidence scores of corresponding frames.

36. The method of claim 13 further comprising:

automatically calibrating a 3D coordinate system that corresponds to a 3D coordinate system of a portal scene.

14. A method of providing portal security, comprising:

generating a target volume from plural 2D images of a field of view about a portal;

dynamically varying the target volume according to a position of the portal;

detecting people candidates within the target volume; and

tracking the people candidates moving through the target volume to detect a portal access event.

16. A method of providing portal security, comprising:

limiting a field of view about a portal;

generating a target volume from plural 2D images of the limited field of view;

detecting people candidates within the target volume; and

tracking the people candidates moving through the target volume to detect a portal access event.

24. A method of portal security, comprising:

generating an entry target volume from plural 2D images of a field of view about an entry of a portal;

generating an exit target volume from plural 2D images of a field of view about an exit of the portal;

detecting people candidates within the entry target volume and the exit target volume; and

tracking the people candidates moving through the entry target volume and the exit target volume to detect a portal access event.

37. A method of providing portal security, comprising:

providing a target having a pattern, the pattern having points in known world coordinates;

capturing two dimensional images of the pattern;

determining three dimensional camera coordinates for the points of the pattern from the two dimensional images; and

generating a transform for converting any three dimensional camera coordinate into corresponding three dimensional world coordinates from the known world coordinates and the three dimensional camera coordinates for the points of the pattern.