Video system manufacturers have been trying to make movable (dome or pan/tilt) cameras follow specific subjects automatically, thus greatly reducing the work load of the guard. These devices can work in isolated cases, where very little activity exists in the image and only the lone moving object needs to be followed. However, in a busy store, or where the subject passes behind a post or other obstruction, the camera does not know what to do with very unsatisfactory results.
A new technology is emerging where tagged items located within some form of detection grid, can be located on a computer map in real time. As the tagged item or person moves within the detection grid, a symbol representing the tagged object moves on the computer generated map. This system does not depend on movement, and other activity is irrelevant. In some embodiments these items can also be identified by an item specific code to differentiate one from another.
Consider a casino where a key high roller is given a nice key chain, which is in fact a location tag. The casino will know exactly where this person is. In a similar way, valuable assets or objects can also be tagged and tracked. If a guard or security system operator can see the map, he can command cameras to record and follow any particular tag or group of tags.
The FIG. 1—Camera, Tag, Receivers, and Tracked Object—shows a tag system as are known to those skilled in the art for real time locating system (RTLS). The system outputs data defining the x and y coordinates (using the tag system map coordinates) of one or more tagged or identified items to be observed and or followed by the video system. The connection to the coordinate processor is typically a digital network, USB, or RS422 type communication link.
A real time locating system is used to provide coordinates that can select an appropriate camera to provide an image to a monitor of a selected item that periodically emanates a radio transmission signal by means of a tag or similar signal emitter. The emanation or tag can provide an identification information. The system can be programmed to determine if the tag is an item that needs to be displayed on a video monitor or can be ignored as a low priority event. If viewing is determined the following procedure is started. The data goes to a module that compares available camera coordinates in the camera system to the observed tag coordinates, and outputs the ID numbers or addresses of the cameras in proximity to the tag in question. This module also contains logic or tables that can logically compare possible camera fields of view against the tag location coordinates. The available camera field of view coordinates must be scaled and offset, and possibly coordinate converted to match the tag system so they can be compared to the tag coordinates to determine which cameras can see the tagged object. Pan and tilt or dome type movable cameras can include their full range of pan, tilt, and zoom as available for viewing. Multiple floors and buildings must also be accommodated in this comparison.
The identify and camera select module can also receive priority inputs so that the best of two or more cameras, or more than one of many possible cameras can be commanded to observe the object, allowing the lower priority units to possibly not be recorded or available for viewing a second tag. These priorities may also be stored in the camera data file. The identify module outputs commands to the video system to connect and view the selected cameras and to start recorders, turn on lights, open doors etc.
Once a camera is selected, if it is movable its identification must be sent to the convert and scale module. The specific tag coordinate system can be converted to the camera coordinate system and appropriate commands given to move the camera through the video camera control system. Alternately, the camera coordinate system can be converted to the coordinate system of the tags, and camera movement commands transmitted to the camera. This communication line, labeled camera movement commands, uses similar methods as the others and sends camera movement commands from the coordinate conversion system to the video system. Note that the convert and scale module movement command output can be filtered and smoothed so that the camera moves smoothly and does not exhibit jerky or erratic motion.
Both the identifier module and the coordinate converter/scalar module obtain data from one or more tables that store the location and field of view and coordinate system for each camera. This is shown as the camera data file.
The Robinson U.S. Pat. No. 6,700,493 describes a system for real time tracking of objects but does not disclose real time video tracking based on locating the object with his invention. U.S. Pat. No. 7,321,305 also describes a system for locating an object. The white paper “Virtual Security Shield”, Duos Technologies, Inc Jul. 24, 2008 discusses using RFID (radio frequency identification) and RTL (real time location) and then the use of a PTZ (pan, tilt, zoom) camera that is manual controlled by an operator to observe the object. This invention shows how this can be automated.
The concept is to integrate the position data from the tag system in a building, open area or rooms 1 into the video security management system as shown in
The movable cameras 2 can be commanded to move to place the tag 4 coordinates in the center of the field of view, or some offset of the field of view of the camera. The camera will move as the tag moves. Fixed cameras can either be turned on and or recorded if the tag is within the possible field of view of the camera. If the movable camera 2 receives roe and theta coordinates, the system will need to convert and associate the camera coordinate system 6, 7, 8, & 9 with the tag map coordinates. This can be accomplished exactly with a simple computer computation, or a table with reasonable granularity or resolution used to equate the map points with the camera points, or vice versa. Even with the same coordinate system, appropriate data scaling and offsets are required as are well known in the art. For example, zero for the dome is directly under it, but this is usually a non zero point on the tag map. A scaling and offset correction is still needed even if the camera coordinate system does match the tag system, as the point under the camera 2 will not likely equal the tag 4 coordinates.
A variety of smoothing algorithms well know in the art can be used to prevent rapid jerky motion of the cameras 2 when following the tag 4.
If the system is tracking two or more tags 4 at the same time, there is no conflict if the tags are physically separated and uniquely identifiable. However, if two tags are in the viewing range of one or more cameras 2, the system can select the closest camera to each tag first, and alternate between tags in making the next best camera selection for each tag. Alternately, if there is not enough camera coverage available, a priority system determined on setup can be established to select a camera for the highest priority tag first, the next camera for the next priority tag, etc.
The video stream from the selected camera 2 can be sent to a monitor 11. A virtual IP based switch or traditional analog matrix switch 10 can be used to connect the select the camera to the desired monitor and be used to send the PTZ coordinates to the selected camera.
For cost and installation savings reasons it is advantageous to employ the object tracking tag receivers in or adjacent to a camera assembly 2 and at the camera control or signal receiving location 5. This allows sharing or power wiring and adding the tracking signals into the camera signal or into the same system wiring (IE one wire or cable or fiber or wireless channel communicating both signals) to minimize wiring for the entire system. If the system is network based, providing both the video and the tracking system over the same communication connection with either the same or two separate network addresses.
Some of the key elements of the concept are:
This application is related to and claims the benefit of U.S. Provisional Patent Application Ser. No. 61/165,097 filed Mar. 31, 2009, entitled Tag Tracking System, the entirety of which is incorporated herein by reference.
Number | Date | Country | |
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61165097 | Mar 2009 | US |