Abstract:
The invention provides an apparatus and method for automatic monitoring and control of the ingress and egress of vehicles to and from a secure facility and various areas within the facility. A plurality of cameras, such as infrared-sensitive cameras, captures images of the license plates and/or optically readable passive tags of vehicles traveling into and within the site. The system will also be upgradeable to interface with Electronic Vehicle Identification (EVI) Systems once all vehicles emit such information. Alternatively, the system can be configured to work with RF tags providing ALL vehicles entering the site are issued with such devices and the appropriate sensing technology is installed as part of the site infrastructure. One of the advantages of the system outlined in this application is the use of the vehicle license plate or low cost passive optically readable tag as a unique vehicle identifier.  
     The system also provides a historical database of license plate information not yet available by any other technological means. A video image processing system, such as a software engine running on a computer processor, detects and extracts a vehicle license plate number (LPN), optically readable passive tag or other such identifying characters, within the captured image of the license plate. Based at least in part on the location of the camera that captured the LPN, the processor stores the LPN with a time-stamp in one or more databases, such as a site LPN database, an in-transit “temporary” LPN database, an employee database, an expected visitor database, a “blacklist” database, a loiterer database, a speeder database, a high-security database, a high-security parking lot database, a normal security parking lot database, and a visitor parking lot database or similar such databases as mandated by the facility. Also, depending at least in part on the location of the camera that captured the LPN and whether the vehicle&#39;s LPN is listed in one or more of the above-listed databases, the processor controls the actuation of various barriers or such like devices to allow ingress to and egress from various locations defined throughout the site. The processor also preferably controls information posted on various terminals in the site, such as a Security Portal terminal and a parking lot pay booth terminal and on variable messaging signs at various locations within the site.

Description:
[0001]    This application claims priority to copending provisional patent application number 60/472,537 filed May 22, 2003 titled AUTOMATED SITE SECURITY, MONITORING AND ACCESS CONTROL SYSTEM. 
     
    
     
       FIELD  
         [0002]    This invention relates to security systems. More particularly, the invention relates to the use of cameras and other monitoring devices to provide for automated monitoring and access control of vehicular traffic within secured areas.  
         BACKGROUND  
         [0003]    In today&#39;s world, there is an ever-growing concern about limiting and controlling access to areas containing highly-sensitive information and personnel, such as Department of Defense and Department of Energy facilities, research laboratories, airports and military installations. There is also concern about protecting the security of students, such as on high school or university campuses. In the private sector, business operations that occupy large areas, such as hotels and resorts, cruise liner terminals, airports, country clubs, container ports, and large multi-level parking facilities, have a need for monitoring and controlling vehicular access to various zones within the area occupied by the business. Security and vehicular access control may also be mandated for private gated communities.  
           [0004]    Prior security systems designed to monitor and control access to such facilities have been lacking in many respects. What is required, therefore, is an improved integrated security system for automatically controlling access to secure areas, for monitoring the movements of vehicles that have been granted access to the secure areas and for providing information in real time to both manned and unmanned security locations regarding such access and movements.  
         SUMMARY  
         [0005]    The above requirements and others are met by an apparatus for automatically monitoring and controlling the ingress and egress of vehicles to and from a facility and various areas within. A preferred embodiment of the invention includes a plurality of cameras, such as infrared-sensitive cameras, for capturing images of the license plates of vehicles traveling into the facility, within the facility, and even exiting the facility. The apparatus includes a video image processing system, such as a software engine running on a computer processor, for detecting and extracting a vehicle license plate number (LPN), or other such identifying characters, within the captured image of the license plate. Based at least in part on the location of the camera that captured the LPN, the processor stores the LPN with a time-stamp and other pertinent information in one or more databases. These databases can include but are not limited to, a site LPN database, an in-transit LPN database, an employee database, an expected visitor database, a blacklist database, also known as “license plates of interest”, a loiterer database, a speeder database, a high-security database, a high-security parking lot database, a normal security parking lot database, and a visitor parking lot database. Depending on the location of the camera that captured the LPN and whether the vehicle&#39;s LPN is listed in one or more of the above-listed databases, the processor controls the activation of various physical barriers to allow ingress to and egress from defined areas throughout the site. The processor controls information posted on various terminals in the site, such as a Security Portal and a parking lot pay booth, and on Variable Messaging Signs (VMS) at various locations within the site.  
           [0006]    In one preferred embodiment, the video image processing is performed on processors, such as in personal computers or dedicated image processors networked throughout the site. In an alternative embodiment, the video image processing is performed on a single processor that serves all of the cameras in the site.  
           [0007]    The cameras can communicate with the video image processing system and/or the main processor by way of a communication network, such as a local area network (LAN), modem, RF modulator, wide area network (WAN), or global network such as the Internet.  
           [0008]    The invention provides an automated system for performing various site security monitoring and site access-control actions based upon the different event types as defined by the user. The invention is an event-driven system activated by a camera reading a license plate and/or a temporary passive tag issued and controlled by the facility. The reading of the license plate is triggered either by the plate being detected within the camera video or by an optional trigger such as a light curtain or embedded loop. Events are processed to update the underlying vehicle license plate number (LPN) data held in various databases (or in various tables within a single database). Separate databases are maintained such as the site as a whole, for an employee parking lot, for a high-security parking lot, and for a visitor parking lot. In an alternative embodiment, the LPN information for the various facilities within the site may be stored in a single database. In addition, a loiterer database and speeder database may be created for the respective event types.  
           [0009]    In one preferred embodiment, the employee parking lot is split across two levels with respective databases for level  1  and level  2 , and the number of unoccupied parking spaces in each level is displayed on variable message signs.  
           [0010]    Preferably, all vehicles entering the site are recorded on the site database. Vehicles in the employee parking lot, high-security parking lot or visitor parking lot are entered in the respective inventory databases. Vehicles which are not in these databases, but which are in the site database, are in transit on the site. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    Further advantages of the invention are apparent by reference to the detailed description when considered in conjunction with the figures which are not to scale so as to more clearly show the details, wherein like reference numbers indicate like elements throughout the several views, and wherein:  
         [0012]    [0012]FIG. 1 depicts a functional block diagram of a site security, monitoring, and access control apparatus according to a preferred embodiment of the invention;  
         [0013]    [0013]FIG. 2 depicts components of the site security, monitoring, and access control apparatus according to a preferred embodiment of the invention;  
         [0014]    [0014]FIGS. 3-10 depict steps in event-driven monitoring and access control processes according to preferred embodiments of the invention; and  
         [0015]    [0015]FIG. 11 depicts a functional block diagram of a site security, monitoring, and access control apparatus according to an alternative embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]    Depicted in FIGS. 1 and 2 is an automated system  10  for controlling access to a secure site, such as a military base or high-security research facility, and for monitoring location of vehicles traveling within the site. The system  10  includes a number of monitoring cameras, such as cameras C 1 -C 14  depicted in FIG. 2 for capturing images of license plates, or of a passive tag issued by the facility, of vehicles entering, traveling within and exiting the site. In the preferred embodiment, the cameras C 1 , C 3  and C 5 -C 14 , include an integrated infrared emitter for providing infrared illumination to a retro reflective surface on the license plate, such as cameras manufactured by PIPS Technology, Inc. of Knoxville, Tenn. under model numbers P356, P366, or P362. Using infrared illumination, the cameras C 1 , C 3  and C 5 -C 14  will covertly capture a license plate image at night or in the daylight. Where a vehicle does not display a license plate, an alternative passive tag will be issued by the facility and read in the same manner. The cameras C 2  and C 4  are preferably standard visible-light color video cameras.  
         [0017]    Although the cameras C 1 , C 3  and C 5 -C 14  of the preferred embodiment are infrared cameras, the system  10  described herein may also incorporate visible light cameras with appropriate illumination if necessary for license plate image capture. Thus, it will be appreciated that the invention is not limited to any particular type of camera or imaging wavelength.  
         [0018]    In the preferred embodiment of the invention, some or all of the cameras C 1 -C 14  are connected to a video image processing system  12  via a communication network  14 . The network  14  may be hard-wired, wireless, or fiber optic.  
         [0019]    The video image processing system  12  receives video images captured by the cameras C 1 , C 3  and C 5 -C 14 , such as images of vehicle license plates, and processes those images to recognize characters within the images, such as the vehicle license plate number (LPN) on the license plate. The video image processing system  12  may include a realtime hardware license plate detector such as described in United Kingdom patent number GB 2,332,322 entitled “Detection of Vehicle License Plates,” or a software-based system such as used in the PIPS Technology PC-based “Autoplate” software. The video image processing system  12  provides the LPN to a main processor  16  that performs several functions based on the LPN, as described in more detail hereinafter.  
         [0020]    In the embodiment depicted in FIG. 1, the video image processing system  12  is a central system that receives and processes video information from the multiple distributed video cameras C 1 , C 3  and C 5 -C 14 . However, it will be appreciated by those skilled in the art that the video information processing could be distributed rather than central. For example, in an alternative embodiment of the invention depicted in FIG. 11, there are separate distributed video image processing systems  12   a - 12   f  associated with the cameras C 1 , C 3  and C 5 -C 14  used to capture vehicle license plate information. In the alternative, a remote processor could handle the input from the cameras. In this alternative embodiment, each of the distributed video image processing systems  12   a - 12   f  extracts the LPN from the license plate image captured by the local camera or cameras, and communicates the LPN, with a time-stamp and other pertinent information to the main processor  16  via the communication network  14 . In the distributed system of FIG. 11, the barriers and VMS&#39;s are preferably controlled by the remote processors  12   a - 12   f , such as the processors provided in the model P357 Processor manufactured by PIPS Technology Inc. While using remote processing to control such items as physical barriers, the system  10  could still refer to a central database or databases for the status of the vehicle.  
         [0021]    The communications infrastructure in such a distributed system requires less bandwidth because less video information is being transmitted over the communication network  14 . The examples of system operation described hereinafter may be carried out using the central video image processing system  12  (FIG. 1) or the distributed video image processing systems  12   a - 12   f  (FIG. 11).  
         [0022]    The main processor  16  has access to several databases, wherein LPNs are cross-referenced with other pertinent information. For example, as described in more detail below, the Site LPN Database  18  cross-references the LPNs of each and every vehicle that is within the site with the name of the vehicle operator, an image of the vehicle operator, the zones within the site to which the vehicle may have access, the time of the vehicle entry into the site, and other pertinent information. Other of the databases are described hereinafter. These databases are preferably stored on mass storage devices, such as magnetic or optical disks, directly interfaced to and co-located with the main processor  16 . Alternatively, the databases may reside on one or more storage devices located remotely from the main processor  16 , and accessed by the main processor  16  through the communication network  14 .  
         [0023]    With reference to FIG. 1, the main processor  16  is connected to one or more barrier control interfaces  20  through the communication network  14 . Based on signals provided by the main processor  16 , the barrier control interfaces  20  control barriers within the site  10  that may be opened to allow vehicles to proceed into or out of particular zones within the site  10 , or closed to impede vehicle movement from one zone to another. Within the site  10  depicted in FIG. 2, there are six barriers B 1 -B 6 .  
         [0024]    As shown in the preferred embodiment of FIG. 1, the main processor  16  is also connected via the communication network  14  to variable messaging signs (VMS)  22 ,  24 ,  26 , such as signs manufactured by Addco and other such VMS suppliers. As the name implies, the message displayed on these signs may be changed based upon signals provided by the main processor  16 . Exemplary uses of the signs  22 ,  24 ,  26  are described in more detail below.  
         [0025]    Also connected to the main processor  16  via the communication network  14  are remote communication terminals  28 , such as a Security Portal  28   a  and a pay booth terminal  28   b . As described in more detail hereinafter, the communication terminals  28  are used to communicate information from the main processor  16  to security and other personnel, such as in the Security Portal or pay booth. In the preferred embodiment, the communication terminals  28  are personal computers.  
         [0026]    As depicted in the flow diagram of FIG. 3, various actions performed by the system  10  are triggered by certain events, such as the detection of a vehicle in a particular location on the site. In a distributed system, such as depicted in FIG. 11, a physical presence trigger signal can be connected locally to the local Video Image Processor  12   a - 12   f , rather than having to be communicated to the central processor.  
         [0027]    In a preferred embodiment of the system  10 , the presence of a vehicle is sensed by any one of the cameras C 1 , C 3  and C 5 -C 14 , such as by detecting a license plate within an image of the vehicle. In other embodiments, the physical presence of a vehicle is sensed by a vehicle presence trigger or sensor, such as a magnetic sensor embedded in the pavement or an infrared sensor. Generally, physical presence sensors are used in the highest security applications, such as in detecting a vehicle approaching the entrance gate. Video triggering alone may be used in lower security applications, such as speed detection. In any event, it will be appreciated by those skilled in the art that either or both types of triggering may be used to initiate a sequence of events as described below, and that the invention is not limited to any particular type of event triggering.  
         [0028]    As described in more detail below, once the presence of a vehicle has been detected, the subsequent processing steps preferably depend upon the location of the vehicle in the site. In the preferred embodiment, the location of the vehicle in the site is associated with a particular camera positioned at the location. Thus, in the processing described herein, the processing steps are determined by identification number of the camera at the location where the vehicle is detected.  
         [0029]    As depicted in FIGS. 1, 2, and  3 , when a vehicle approaches a camera location, the camera captures an image of the vehicle&#39;s license plate (step  102 ). In the preferred embodiment, a time-stamp, camera identifier and other pertinent information are associated with the image of the plate (step  104 ). Preferably, the time-stamp is information indicating the time and date that the image of the vehicle license plate was captured. The camera identifier is information indicating which camera in the system  10  captured the image of the license plate. For example, the camera identifier may be a TCP/IP address of the camera on the communication network  14 . For purposes of this description, the cameras are identified by the reference numbers C 1 -C 14 . The image of the plate is transferred to the image processing system  12 , such as via the communication network  14 , and the image processing system  12  recognizes the characters of the LPN in the image of the plate using character recognition techniques, such as employed in products such as the PIPS Technology Inc. model P357 dedicated Automated License Plate Recognition (ALPR) processor or its “Autoplate” PC based ALPR software. (step  106 ). The LPN is then associated with the time-stamp, plate image, and other pertinent information.  
         [0030]    If the location of the vehicle corresponds to camera C 1  (step  108 ), processing continues at point A in the flow diagram of FIG. 4. In the preferred embodiment, cameras C 4  and C 2  capture images of the driver and the front of the vehicle, respectively (step  142 ). The images of the vehicle license plate (from camera C 1 ), the driver (from camera C 4 ), and the vehicle overview (from camera C 2 ) are then associated with the LPN (step  144 ).  
         [0031]    As shown in FIG. 1, the system  10  may include an employee LPN database  30  in which the LPNs of all vehicles registered to the site employees are associated with other employee information, such as the employee name, identification number, security clearance level, zones within the site to which the employee may have access and employee photograph. The embodiment of the system may include an expected visitor database  32  in which the LPNs of all vehicles registered to expected visitors are associated with other visitor information, such as the visitor&#39;s name, the date of the expected visit, the name of the employee to be visited, and the zone(s) within the site to which the visitor may have access.  
         [0032]    If properly engineered, the database entries can provide a full historic record of all significant vehicle movements within the site, so that in the event of an ‘incident,’ the historic record, including the captured images, can be searched in order to provide evidence of the perpetrator. The system not only provides enhanced security measures, it also can be used as an evidentiary tool enabling historical data to be accessed. As an example, the status of a ‘visitor’ may not have been correctly identified at the Security Portal.  
         [0033]    With continued reference to FIGS. 3 and 4, if the LPN recognized at step  104  is in the employee database  30  or the expected visitor database  32  (steps  146 - 148 ), the vehicle will be authorized for admittance to the site. As part of the preferred admission process, the LPN and a time-stamp are added to the site LPN database  18  (step  150 ) and to an In-Transit LPN database  19 . Any additional information from the employee LPN database  30  or the expected visitor database  32  associated with the LPN is preferably stored in the site&#39;s LPN database  18 . Preferably, images captured by the cameras C 4  and C 2  are also stored at this time, such as in an image storage device  34 , and are associated with the LPN or other identifying information (step  152 ).  
         [0034]    In the preferred embodiment, the barrier B 1  is opened in response to a signal communicated from the main processor  16  to the barrier control interface  20  via the communication network  14  (step  154 ). In this manner, no human intervention is required to raise the barrier B 1  and allow entry of the vehicle into the site, if the vehicle&#39;s LPN is in the employee LPN database  30  or the expected visitor database  32 . Alternatively, the barrier B 1  may be opened by a manual control located in the Security Portal.  
         [0035]    If the LPN recognized at step  104  is not in the employee database  30  or the expected visitor database  32  (steps  146 - 148 ), a “blacklist” database  36  is accessed to determine whether the LPN is stored therein (step  156 ). The “blacklist” database  36  preferably contains the LPNs associated with vehicles that are to be denied access to the site for any reason determined by the site facility management. For example, the “blacklist” database  36  may include the LPNs of vehicles used previously by persons who have violated security restrictions on the site or by persons known to be wanted by law enforcement officials and/or known or suspected terrorists. This may include both national, international and domestic suspects.  
         [0036]    If the LPN recognized at step  104  is in the “blacklist” database  36  (step  158 ), security personnel are automatically notified (step  160 ). Preferably, the main processor  16  provides this notification by sending a configurable alert message and/or tone to the Security Portal that will be displayed on a display device  28   a  in the Security Portal. Additionally, an alert message may be e-mailed to security officials, on-site or off-site, who are authorized to be informed or warned that a “blacklisted” vehicle was attempting to enter the site.  
         [0037]    If the LPN recognized at step  104  is not in the “blacklist” database  36  (step  158 ), security personnel in the Security Portal are notified that personal intervention is required (step  162 ). For example, security personnel may question the driver of the vehicle regarding his or her destination and business on the site, and the employee to be contacted to confirm whether the stated business is legitimate. If the vehicle is to be admitted (step  164 ), processing preferably continues at step  150 . If the vehicle is not to be admitted (step  164 ), processing preferably continues at step  160 .  
         [0038]    If the location of the vehicle corresponds to camera C 14  (step  110 ), the LPN, time-stamp, and camera identifier are added to the in-transit LPN database  19  (step  132 ) to be accessed in subsequent processing.  
         [0039]    If the location of the vehicle corresponds to camera C 9  (step  112 ), processing continues at point B in the flow diagram of FIG. 5. Preferably, the LPN, time-stamp and camera identifier are added to the in-transit LPN database  19  (step  166 ). The time-stamps associated with cameras C 9  and C 14  are retrieved from the in-transit LPN database  19  for the current LPN (step  168 ), and the time taken for the vehicle to travel from camera C 14  to C 9  is calculated (step  170 ). If the vehicle travel time between cameras C 14  and C 9  is greater than the facility&#39;s predetermined maximum time (step  172 ), then the vehicle is designated as a “loiterer”. This may occur, for example, if the operator of the vehicle made an unauthorized stop to take photographs of a sensitive facility at some point between the two cameras. In this situation, the vehicle LPN and time-stamp are added to a loiterer database  38  (step  174 ). In a preferred embodiment, security personnel are automatically notified when a LPN is added to the loiterer database  38  so that the security personnel may take appropriate action at the appropriate time.  
         [0040]    In an alternative embodiment, when a vehicle passes camera C 14 , or otherwise is detected near the location of camera C 14 , the LPN, time-stamp, and camera identifier are added to the in-transit LPN database  19 . At the same time, a counter or timer begins to measure elapsed time. If a maximum predetermined time elapses before the vehicle is detected at camera C 9 , the vehicle LPN and time-stamp are added to the “loiterer” database  38  and security personnel are automatically notified.  
         [0041]    If the vehicle travel time between cameras C 14  and C 9  is less than facility&#39;s predetermined minimum time (step  176 ), then the vehicle is designated as a “speeding violator”. This may occur, for example, if the vehicle exceeds the posted speed limit on the section of road between the two cameras. In this situation, the vehicle LPN and time-stamp are added to a speeder database  40  (step  178 ). Preferably, security personnel are automatically notified when a LPN is added to the speeder database  40  so that the security personnel may take appropriate action at the appropriate time. Also, the main processor  16  may generate a notification that is communicated through the communication network  14  to the VMS  22  to notify the operator of the vehicle that the vehicle had been in violation of the posted speed limit.  
         [0042]    With continued reference to FIGS. 2 and 5, when the vehicle has been detected at camera C 9 , the system  10  of the preferred embodiment activates the VMS  22  to provide pertinent information to the driver of the vehicle (step  182 ). This is preferably accomplished by first accessing the site LPN database  18  to determine the destination of the vehicle within the site (step  180 ). The VMS  22   a  is then activated to display a message, such as information regarding the vehicle&#39;s destination. For example, if the information accessed from the site LPN database indicates that the vehicle is destined for the visitor parking lot, the VMS  22   a  may display directions to that destination.  
         [0043]    If the location of the vehicle corresponds to camera C 6  at the entrance to the high security parking lot (step  114 ), processing continues at point C in the flow diagram of FIG. 6. In the preferred embodiment, the main processor  16  accesses a high-security database  42  (step,  184 ), and a determination is made whether the detected LPN, is, listed therein in association with an employee or visitor having a high-security clearance (step  186 ). If the detected LPN is in the high-security database  42  (step  186 ), a signal is provided via the barrier control interface  20  to raise the barrier B 4  or a like device to allow the vehicle to proceed into the high security parking lot. Preferably, the vehicle&#39;s LPN and associated time-stamp are then added to a high security parking lot inventory database  44 . If the detected LPN is not in the high-security database  42  (step  186 ), the vehicle is denied entry into the high security parking lot and security personnel are automatically notified (step  188 ).  
         [0044]    With reference to FIG. 3, if the location of the vehicle corresponds to camera C 5  at the exit from the high security parking lot (step  114 ), the LPN is removed from the high security parking lot inventory database  44  (step  136 ), and the LPN, time-stamp and camera identifier (such as C 5 ) are added to the in-transit LPN database  19  (step,  138 ). This process-is repeated so long as the vehicle remains on the monitored facility.  
         [0045]    As depicted in the flow chart of FIG. 3, if the location of the vehicle corresponds to camera C 10  at the entrance to the visitor parking lot (step  118 ), processing continues at point D in the flow diagram of FIG. 7. In the preferred embodiment, the detected LPN may be associated with a parking ticket number (step  194 ), such as the next parking ticket number in a sequence of numbers, and the image of the vehicle license plate captured by the camera C 10  is stored in association with the LPN and ticket number (step  195 ). A parking ticket dispenser  24  is then activated to dispense a parking ticket having printed thereon the parking ticket number associated with the LPN (step  196 ). In addition to a numeric representation of the ticket number, there is also preferably an encoded version of the ticket number, such as in a bar-code or encoded magnetic stripe. In the preferred embodiment, once the ticket has been removed from the parking ticket dispenser  24 , the barrier B 3  is raised (step  198 ), and the LPN, time-stamp, and ticket number are added to the visitor parking lot inventory database  48  (step  200 ). The processes mentioned herein generally relate to those facilities that utilize automated ticket dispensers as part of there parking control.  
         [0046]    If the location of the vehicle corresponds to camera C 11  at the exit from the visitor parking lot (step  120 ), processing continues at point E in the flow diagram of FIG. 8. The preferred embodiment of the invention includes a ticket reader  26  for receiving the parking ticket from the vehicle operator and for reading the encoded parking ticket number from the parking ticket (step  202 ). In one preferred embodiment, the ticket reader  26  comprises a bar-code reader. After the ticket number has been read from the parking ticket, the visitor parking lot inventory database  48  is accessed to retrieve the LPN that was associated with the ticket number at the time the ticket was dispensed (step  204 ). If the LPN retrieved from the visitor parking lot inventory database  48  matches the LPN captured by the camera C 11  at the exit from the parking lot (step  206 ), a parking fee is calculated based upon the duration of stay as computed by the system. The calculated fee becomes due prior to exit.(step  208 ). The LPN and time-stamp are then added to the in-transit LPN database  19  (step  210 ), and the barrier B 2  is raised to allow the vehicle to exit the visitor parking lot (step  211 ). As outlined in the preceding paragraph, all of these processes lend themselves to commercial applications. Even in this environment, enhanced security will be achieved.  
         [0047]    If the LPN retrieved from the visitor parking lot inventory database  48  does not match the LPN captured by the camera C 11  at the exit from the parking lot (step  206 ), the system  10  initiates a process to resolve the mismatch. In the preferred embodiment, the image of the vehicle license plate associated with the ticket number read by the ticket reader  26  is retrieved and displayed at the pay booth terminal  28   b  (step  212 ). Also displayed at the pay booth terminal  28   b  is the image of the vehicle license plate captured by the camera C 11  (step  212 ). Preferably, the booth attendant will visually compare the two images to determine a match (step  212 ).  
         [0048]    If the visual check indicates that the LPN of the license plate imaged by the camera C 11  does not match the LPN of the license plate imaged by the camera C 10  that was associated with the ticket number (step  214 ), the pay booth attendant manually corrects the LPN in the visitor parking lot inventory database  48  to match the LPN shown in the images (step  216 ). This manual intervention would generally only occur in exceptional circumstances. The LPN and time-stamp are then preferably added to the in-transit LPN database  19  (step  210 ), and the barrier B 2  or like device is actuated to allow the vehicle to exit the visitor parking lot (step  211 ).  
         [0049]    If the visual check indicates that the LPN of the license plate imaged by the camera C 11  does not match the LPN of the license plate imaged by the camera C 10  that was associated with the ticket number (step  214 ), the parking supervisor could be notified, preferably automatically such as by email, that personal intervention is necessary (step  218 ). This situation occurs, for example, if someone attempts to exit the parking lot using a ticket that was dispensed to the driver of another vehicle.  
         [0050]    If the location of the vehicle corresponds to camera C 8  at the entrance to the normal security parking lot (step  122 ), processing continues at point F in the flow diagram of FIG. 9. In the preferred embodiment, the main processor  16  accesses the employee database  30  (step  220 ), and a determination is made whether the detected LPN is listed therein (step  222 ). If the detected LPN is in the employee database  30  (step  222 ), the vehicle&#39;s LPN and associated time stamp are then preferably added to a normal-security parking lot first level inventory database  50   a  (step  224 ), and removed from the in-transit LPN database  19  (step  226 ). A signal is provided via the barrier control interface  20  to actuate the barrier B 5  or like device to allow the vehicle to proceed into the normal-security parking lot (step  228 ). In the preferred embodiment, a value indicating the number of remaining unoccupied parking spaces in level one of the parking lot is decremented (step  230 ). Preferably, this value is a record stored in the normal-security parking lot first level inventory database  50   a . The number of unoccupied parking spaces in levels one and two of the normal-security parking lot are then preferably displayed on the VMS  22   b  at the entrance to level one of the normal-security parking lot, and on the VMS  22   c  at the entrance to level two of the normal-security parking lot (step  232 ). This process would apply regardless of the number of levels available in each parking lot.  
         [0051]    If the detected LPN is not in the employee database  30  (step  222 ), the vehicle is denied entry into the normal-security parking lot by the use of a barrier or like device and an automatic message is displayed on the VMS  22   b  to direct the vehicle to the authorized parking lot (step  234 ). Security personnel can be automatically notified that an unauthorized vehicle has attempted entry into an unauthorized parking lot.  
         [0052]    If the location of the vehicle corresponds to camera C 12  at the entrance to level two of the normal-security parking lot (step  124 ), processing continues at point G in the flow diagram of FIG. 10. In the preferred embodiment, the vehicle&#39;s LPN and associated time stamp are preferably removed from the normal-security parking lot first level inventory database  50   a  (step  236 ), and added to the normal-security parking lot second level inventory database  50   b  (step  238 ). Preferably, the value indicating the number of unoccupied parking spaces in level one of the parking lot is incremented (step  240 ), and a value indicating the number of unoccupied parking spaces in level two of the parking lot is decremented (step  242 ). In the preferred embodiment, the value indicating the number of unoccupied parking spaces in level two of the parking lot is a record stored in the normal-security parking lot second level inventory database  50   b . The number of unoccupied parking spaces in levels one and two of the normal-security parking lot are then preferably displayed on the VMS  22   b  at the entrance to level one of the normal-security parking lot, and on the VMS  22   c  at the entrance to level two of the normal-security parking lot (step  244 ).  
         [0053]    If the location of the vehicle corresponds to camera C 13  at the exit from level two of the normal-security parking lot (step  126 ), processing continues at point H in the flow diagram of FIG. 10. In the preferred embodiment, the vehicle&#39;s LPN and associated time stamp are preferably removed from the normal-security parking lot second level inventory database  50   b  (step  246 ), and added to the normal-security parking lot first level inventory database  50   a  (step  248 ). Preferably, the value indicating the number of unoccupied parking spaces in level two of the parking lot is incremented (step  250 ), and a value indicating the number of unoccupied parking spaces in level one of the parking lot is decremented (step  252 ). Again, the number of unoccupied parking spaces in levels one and two of the normal-security parking lots are then preferably displayed on the VMS&#39;s  22   b  and  22   c  (step  244 ).  
         [0054]    If the location of the vehicle corresponds to camera C 7  at the exit from level one of the normal-security parking lot (step  128 ), processing continues at point I in the flow diagram of FIG. 10. In the preferred embodiment, the vehicle&#39;s LPN and associated time stamp are preferably removed from the normal-security parking lot first level inventory database  50   b  (step  254 ), and added to the in-transit LPN database  19  (step  256 ). Preferably, the value indicating the number of unoccupied parking spaces in level one of the parking lot is incremented (step  258 ) and the number of unoccupied parking spaces in levels one and two of the normal-security parking lot are displayed on the VMS  22   b  and  22   c  (step  244 ). If the location of the vehicle corresponds to camera C 3  at the exit from the site (step  130 ), the vehicle&#39;s LPN is preferably removed from the site LPN database  18  and the in-transit LPN database  19  (step  140 ).  
         [0055]    The foregoing description of preferred embodiments for this invention have been presented for purposes of illustration and description. Obvious modifications or variations are possible in light of the above teachings and illustrations. The embodiments are chosen and described in an effort to provide the best illustrations of the principles of the invention and its practical application, and to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as is suited to the particular use contemplated.