Retrofitting Digital Video Surveillance System

The present invention relates to a digital video surveillance system and more particularly to a system which connects to and integrates with existing video camera networks, alarm security and other process monitoring systems to enhance physical protection of high-value assets and installations.

Automated security systems have become extremely valuable for protecting highly sensitive facilities. Many security systems available today provide for real-time evaluation of images as viewed by video cameras. Alarm conditions are declared when a sensor detects an intrusion or other abnormal event within the field of view of a camera. See, for example, U.S. Pat. Nos. 4,876,597 to Roy et al., 4,943,854 to Shiota et al. and 4,511,886 to Rodriguez.

Furthermore, some systems now available have the ability to digitize and store video images of a sequence just prior to, during and after an alarm condition. This allows an operator to view what caused the alarm condition so as to take the appropriate action (or inaction). This feature is known as "pre-alarm image recall".

It has been recognized that a security system often must be designed and actually "specialized" or configured for a particular application. For example, there are security systems known which are designed to monitor areas in nuclear power plant facilities. These types of security systems are, however, limited to use only in nuclear power facilities and would need to be completely revised and redesigned to work in other applications. Further, these systems each address only one aspect of physical security providing, for example, only pre-alarm image recall, motion detection or image storage. That the prior security systems of this type are so limited in use is a major draw-back in the art.

It is a primary object of the present invention to provide a digital video surveillance system capable of addressing all aspects of physical security with flexibility for adaption for use in an unlimited number of applications. Specifically, the system according to the present invention provides configuration options to enhance detection, transmit images, assess alarms, improve response force allocation, documentation and guard-force training at secure facilities.

It is another object of the present invention to provide a retrofitting digital video surveillance system to connect to and integrate with an existing security or other process monitoring system to enhance the capabilities of the existing system.

It is another object of the present invention to provide a retrofitting digital video surveillance system which is flexible in installation with an existing security system.

It is yet another object of the present invention to provide a digital video surveillance system to which functions may easily be augmented according to particular applications, and which can integrate with an existing security or process monitoring system.

It is still another object of the present invention to provide a retrofitting digital video surveillance system employing parallel processing computer architecture to achieve complete modularity, expandability and flexibility in configuration.

Briefly, the present invention relates to a digital video surveillance system which preferably retrofits to an existing security system and cooperates with alarm sensors, video cameras and video monitors of the existing security system. The digital video surveillance system comprises a plurality of processing boards having a substantially similar architecture. Several frame grabber/frame storage processing boards are provided, each of which digitizes the analog video signals from the video cameras and stores the digital data in a solid state buffer memory. Several display boards are provided to display the digitized video data on dedicated display monitors. A controller board is further provided to control the exchange of video data and command or control messages over communication links and between processing boards, respectively. Additional expansion boards may be added to support additional buffering and system options. Each processing board is built around a parallel processing computer chip.

The present invention interfaces with security or process monitoring systems such as, for example, those used at facilities requiring real time alarm monitoring and video display of alarm conditions. In a broader sense, the utility of the present invention lies with any type of surveillance, security, personnel access control or other conditions which are monitored; such other conditions may be parameters of physical processes performed by machines.

The above and other objects and advantages will become more readily apparent when reference is made to the following description taken in conjunction with the accompanying drawings.

FIG. 1 is a block diagram illustrating the connection of the retrofitting digital video surveillance system with a conventional video camera network/alarm system.

FIG. 2 is a block diagram illustrating the architecture of the retrofitting digital video surveillance system according to the present invention.

FIG. 3 is a block diagram illustrating the architecture of a controller circuit board of the digital video surveillance system according to the present invention.

FIG. 4 is a block diagram illustrating the architecture of the frame grabber/frame storage circuit board.

FIG. 5 is a block diagram illustrating the architecture of a display circuit board.

FIGS. 6-8 are block diagrams illustrating the variations in which option modules are connected with the Transputer processor on the processing boards.

FIG. 9 is a flowchart diagram depicting the software which controls the function of the frame grabbing processing board.

FIG. 10 is a flowchart diagram depicting the software which controls the function of the controller and display processing boards.

FIG. 11 is a flowchart diagram depicting the software which controls the operation of a digital I/O interface option board.

FIG. 12 is a flowchart diagram depicting the software which controls the alarm sequence buffer option boards.

FIG. 13 is a flowchart depicting the manner in which the system software is loaded into each processing board.

FIG. 14 is a flowchart depicting functions performed by the display board in an alarm mode and a secure mode.

FIGS. 15A and 15B illustrate the display screen in the alarm mode.

FIG. 16 is a top view of the user keyboard according to the present invention.

FIGS. 17 and 18 are views of examples of the display screen menus.

With reference first to FIG. 1, some components of an existing security system are shown connected to the digital video surveillance system (hereinafter referred to as DVSS") 10 according to the present invention. The existing security system may comprise any number and variety of sensing devices but, for explanatory purposes, it is shown to comprise N video cameras 12, N live video monitors 14, a computerized video switch 16 with an associated video switch keyboard 26, alarm sensors 18 with an associated alarm computer 20, access controllers 22 with an associated access control computer 24. The alarm sensors may monitor intrusion, fire, process control, temperature or other situations. The access control computer 24 monitors and controls, for example, personnel access to doors and gates.

The computerized video switch 16 is controlled by the alarm computer 20 and the access control computer 24. Both the alarm computer 20, which monitors the status of the alarm sensors 18, and the access control computer 24 send signals to the computerized video switch 16 to display the live view from the cameras 12 located in protected areas when any of the alarm sensors 18 are tripped or an attempt is made to violate the access control system through the access controller 22. The video switch keyboard 26 allows an operator to manually route a video signal from any camera to any live video monitor.

To integrate the DVSS 10 with an existing security system (also hereinafter referred to as the host security system), all of the input signals to the video switch 16 are tapped so that the DVSS 10 can respond to all events, whether computer or operator generated. Also tapped are the analog video signals from the cameras 12 so that the DVSS 10 may digitize the video data.

FIG. 2 illustrates in detail the architecture of the retrofitting DVSS 10. The DVSS 10 may be configured in many variations depending upon the particular use of the system and the existing security system with which the DVSS 10 integrates.

The heart of the DVSS 10 is the array of processing boards 30. The processing boards are variations of a custom board on which integrated circuit chips are installed. There are three types of processing boards: 1) a controller board 32; 2) several frame grabber/frame storage (FG/FS) boards 34(1)-34(N); and 3) several display boards 36(1)-36(N). Further, each display board is connected to one of a plurality of high resolution video monitors 28. As will be explained hereinafter, each processing board is built around a parallel processing computer chip termed a Transputer which is manufactured by Inmos, Inc., which is a subsidiary of SGS Thomson Microelectronics, of France. Connected to each display board may be an alarm sequence buffer board 35(1)-35(N). The FG/FS boards and display boards are connected in a cascaded configuration outward from the controller board 32.

The controller board 32 is the only board which has direct access to the computers 20 and 24 of the host security system. This is accomplished through a digital I/O interface 41, which also includes a Transputer chip. The interface 41 connects directly with the computer of the host security system and also with other external devices such as a controller keyboard, modem, printer, facsimile machine, etc. In addition, the controller board 32 connects directly to a disk controller 43A which in turn is connected to one or more hard disk drive(s).

The alarm sequence buffer boards 35(1)-35(N) are provided to buffer the sequences of images associated with an alarm event when the built-in buffers of the display boards are full. This may happen only when alarm events occur faster than operator(s) can assess and clear them. A personal computer (PC) 39 may be provided to interface with the controller board 32 and is preferably used to load system software stored on a hard disk via a second disk controller 43B.

The processing boards are connected to each other with Transputer links, which for illustrative purposes are shown by double lines in FIG. 2. A Transputer has 4 links with which to connect with other Transputers. Each Transputer link comprises a group of 4 conductors that directly connect the Transputer processor in each board and permit serial communication at a rate of 20 Mbits/second between processors. While most processors require an array of other components to communicate, the Transputer requires just 4 wires for each of up to 4 links, thus facilitating interconnection. Four links connect each board in the system, two of which are for control messages and one is for digital images. One is left as a spare for communication with option modules and boards.

Control links (CL) 37 are provided between adjacent processing boards. As a result, each Transputer on the respective boards sends messages not designated for its receipt down the line to eventually reach the board designated to receive the message. Each re-transmission of a message to another board inherently adds a latency to the overall transmission time of the message. However, control messages are short and occur at relatively low rates compared to the transmission speed of the link; therefore, this latency is not a problem with respect to control messages. On the other hand, this is not true for the transmission of data intensive digitized video images. Rather, with each image represented by approximately 256K bytes of data, the cascaded transmission process would severely impact the response time of the system to move and display an image. Therefore, a video link 38 is connected to a link switch (shown in FIGS. 3-5) on each board and the respective Transputer connects itself to the video link 38 only when instructed by the Transputer on the controller board 32 (through a control message). As a result, only two Transputers are connected to the video link 38 at any given time thus allowing any two Transputers to communicate video data with a minimum latency. A second video link may be provided in parallel with the other to augment exchange of video data between processing boards should the remaining fourth link of the respective processing board not be needed for connection to option modules or boards.

Also forming part of the DVSS 10 are several option modules 40. These modules fit into expansion sites built onto the boards that meet a published specification for TRAM (Transputer/RAM, referred to hereinafter as TRAM) modules. Consequently, commercially available modules or (specialized modules) may be used with the system to permit unlimited adaptability and expandability. For example, motion detection modules (MD) 42(1)-42(N) may be connected to the FG/FS boards 34(1)-34(N), respectively to analyze the digitized video data for any motion or change in a field of view of any camera associated with the motion detection module. In this regard, the DVSS 10 may have primary detection capabilities. Alternatively, change detection modules (CD) 44(1)-44(N) may be provided and connected to the display boards 36(1)-36(N), respectively, which run an algorithm similar to that run on the motion detection modules except that primary detection is not effected with these modules. The CD modules 44(1)-44(N) identify areas of change in images displayed as a result of an external sensor alarm.

Other types of option modules may be used to support data transmission. For example, the option modules connected to the FG/FS boards may include image data compressors which operate on the digitized images to compress the digital image data. The compressed data is then stored back in the FG/FS board and placed over the video link, when desired. Likewise, the option modules connected to display boards may comprise decompressors to decompress the compressed data which is then supplied to a monitor. This would result in increased image storage capabilities and decreased transmission times. Compressed images could also be communicated out of the DVSS 10 via a modem 201 for decompression in a remote system.

FIG. 3 illustrates the controller board 32 in detail. The controller board 32 comprises a Transputer processor 50, Dynamic Random Access Memory (DRAM) 52, a Transputer link switch 54 (32.times.32 crossbar), Transputer processor expansion sites 56A, 56B, 56C and 56D, and link switches 58 and 60. The link signals of the Transputer 50 are routed through the Transputer link switch 54 to connect either with other processing boards (via link switches 58 or 60) or with any of the installed option modules via the Transputer processor expansion sites. The option modules comprise Transputers, memory and other specialized hardware mounted on small circuit boards (TRAM's) which plug into the expansion sites. Communication with the option modules occurs over the Transputer links.

Specifically, control message signals are transported off the controller board 32 via the link switch 60 in the direction of the destination processor board ("UP" or "DOWN"). The control message signals pass through the normally closed link switches 60 (in the respective processing board). These switches may be opened in order to remove a faulty board from the system so as not to disrupt the control message path or link to the remaining boards. In this case, both of the "link side" contacts of the switch are connected thereby providing continuity of the control link.

An alarm sequence buffer board has an architecture similar to that of the controller board 32.

The video signals from the controller board 32 are transported off-board through the normally opened link switch 58. The Transputer 50 controls the position of the link switch 58. The switch may be closed to connect the Transputer 50 to the video link 38 to transmit video data to or from one of its associated option modules or interfaces and another processing board. In such a case, the Transputer 50 would instruct the Transputer on the corresponding processing board to close its video link switch to establish communications over the video link 38.

When communications are required between two other processing boards, the Transputer 50 on the controller board 32 issues an instruction to both of the Transputers on the other two boards to close their link switches and establish communications. These control messages are transmitted on the control link 37. After the communication of video data is complete, the Transputer 50 of the controller board 32 instructs the Transputers on the two communicating boards to open their link switches and free the video link 38 for other use. Such a process would take place after an alarm event occurs when video data must be transmitted from the proper FG/FS board 34 to the appropriate display board 36.

FIG. 4 illustrates one of the FG/FS boards 34(1)-34(N) in detail. This board digitizes the analog video signal generated by the cameras 1-8 and stores the digital video image temporarily in a hardware FIFO buffer 76. The FG/FS board includes a camera interfacing switch 70 associated with the 8 video cameras. A gen-lock controller 72 is provided and connected to the interfacing switch 70. An analog-to-digital (A/D) converter 74 is connected to the gen-lock controller 72 to digitize the analog video signal to generate a digital video signal which is stored in the FIFO memory 76. The gen-lock controller ensures the proper synchronization of the A/D converter 74 with the analog video signal so that digitizing starts at the top of a video frame and ends at the bottom of the frame. This is critical to ensure frame-to-frame alignment for downstream signal processing. The gen-lock controller 72, A/D converter 74 and FIFO memory 76 comprise frame grabbing circuitry, which is well known in the art.

The output of the FIFO memory 76 is connected to a Transputer processor 80. Associated with the Transputer 80 are DRAM 82, Transputer link switch 84, Transputer processor expansion sites 86A-86D, and link switches 88 and 90. The latter component is analogous to that shown in FIG. 3, as part of the controller board. The switch 88 can connect one or two of the links to the video link 38 for point-to-point communication. That is, the switch 88 can connect to only one, or both of the video links.

As shown in FIG. 4, up to eight cameras can be connected to a single FG/FS board through the switch 70, which is controlled by the Transputer 80. Normally, an image is taken from each camera connected to the switch 70 in succession by way of a conventional multiplexing procedure. The analog video signal is analyzed by the gen-lock controller which passes the video signal together with sync information to the A/D converter 74. The A/D converter 74 digitizes the analog video signal and stores the digital information in a hardware controlled FIFO memory 76, which serves as a buffer. The Transputer 80 then removes the digitized image from the FIFO buffer 76 and stores it in a large software controlled FIFO buffer located in the DRAM 82. The FIFO buffer in the DRAM contains sufficient memory space for storing an entire sequence of images for each camera. For pre-alarm image recall, the system is configured to store M images per camera for viewing after an alarm. These images will then represent pre-, during and post-alarm views. This collection of images is an alarm sequence and this process of successive image capturing continues without end.

The Transputer 80 of the FG/FS board communicates with the rest of the system over the control links (CL). Commands from the Transputer 50 in the controller board 32 are received over the control links (CL) as are messages from other Transputers on various processing boards of the system.

When an event occurs requiring the display of images stored in the FG/FS board, the Transputer 50 on the controller board sends a message requesting the FG/FS Transputer send the particular image(s) for that camera down the video link 38. The FG/FS Transputer then closes the link switch 88 to the video link 38 and transmits the requested image(s) to the Transputer of the proper display board 36. Upon completion of the transmission, the FG/FS Transputer opens the link switch 88, freeing the video link 38 for use by other Transputers in the system.

FIG. 5 illustrates the architecture of a display board in detail. Like the other processing boards, the display board comprises a Transputer 100, DRAM 102, a Transputer link switch 104, Transputer processor expansion sites 106A-106D, and link switches 108 and 110. In addition, the display board comprises a digital-to-analog (D/A) converter graphic controller 112 for displaying images on the associated video monitor according to images represented in the dual-port video random access memory (VRAM) 114. The VRAM is manipulated by the Transputer 100 in response to user commands received from the Transputer 50 of the controller board 32. The DAC 112 is capable of controlling traditional low resolution type displays as well as high resolution color monitors, such as monitors 28.

FIGS. 6-8 illustrate examples of the manner in which a Transputer is connected through its associated link switch to other components. FIG. 6 shows a Transputer 80 on a FG/FS board in cooperation with an option module. Specifically, in this example, a motion detector option module occupies one of the expansion sites on the FG/FS board. The Transputer switch 84 receives the four links from the Transputer 80 and feeds the appropriate three to the corresponding "off-board" destinations while the remaining link is connected to the option module 86A (86B, 86C or 86D). The Transputer switch 84 may be a silicon chip that is instructed by the Transputer 80 to switch a matrix of 32.times.32 links, accordingly. Alternatively, the Transputer switch 84 may be a pre-wired header which would reduce cost in applications where the link configurations will remain constant.

FIG. 7 illustrates an example in which no option modules are connected to the FG/FS board. In this type of configuration, one link is unused or could optionally be routed to an additional video link.

FIG. 8 illustrates an example in which a disk module occupies one of the option module sites of the control board. The control board Transputer 50 interfaces with the Transputer on the disk module 56 via the link switch 54. Specifically, three links from the Transputer 50 are fed "off-board" while a single link is fed to the Transputer on the disk module.

The software which runs on each of the Transputers is written in a language called OCCAM. OCCAM is unique to the Transputer and is designed for parallel processing, both inter and intra processor. That is, each Transputer has multiple programs executing in parallel in the Transputer.

As mentioned above, control messages are passed between the boards over the control link 37. There are no pre-defined message formats. Each message is preceded by a tag indicating how many bytes in the message are to follow. This permits message types to be added at any time without changing the fundamental operation of each board.

In FIGS. 9-12, the numbered circles or "Bubbles" represent individual programs which run on the Transputer chips. These programs run in parallel, but may be dependent upon the results generated by another program running on that Transputer. The intra- and inter-processor parallelism of the Transputer allows the OCCAM programs to be distributed to physical Transputer processors as appropriate for the functional and performance requirements of each application.

With reference to the flowchart of FIG. 9, the function of each of the FG/FS boards as controlled by the software running on each board, will be described. Bubble 1 represents a program for controlling video and control link switching, decoding of message packets and directing required messages to the appropriate board. Bubble 2 represents the frame grabber software control for controlling frame grabbing sequencing, and creation of header information as to camera, time, zone and other appropriate information. Bubble 3 represents the program for frame grabber hardware control which controls the digitizer and gen-lock chips that actually acquire the image and controls the camera input. Bubble 4 represents the software clock which serves as a local time reference from which the frame grabber calculates grabbing sequences. Bubble 5 represents the data manager program which controls access to locally stored image data areas in DRAM from output requests received over the control link 37.

The Transputer of the controller board 32 is responsible for several macro-type of operations. Particularly, the controller board 32 accepts input from all devices external to the DVSS 10. Such external devices include the personal computer 39, serial I/O devices such as alarm computers, video switches, access control card readers, the user keyboard, modems, fax devices, etc. The external devices may also be parallel I/O devices such as a video printer, line printer, etc.

Communication with the host security system is accomplished through an option board 41 capable of RS-232, RS-422 and Centronics parallel communication. Connections to the existing system are made passively by splitting existing communications lines with y-cables or modem splitters. The DVSS 10 maintains a user defined table of command strings and associated actions. The system monitors the existing communications and searches all of the communication messages for these command strings. A.1. in the Appendix is a listing of the software for each Bubble which runs on the FG/FS boards, and described above.

The controller board communicates with disk I/O devices via a Small Computer System Interface (SCSI) disk controller 43. This provides for access to devices that conform to the SCSI protocol, hard disk storage and retrieval, file management, copying and deleting for disk stored files, activity log maintenance, etc.

The controller board 32 also connects to the personal computer (PC) 39 for access to the PC's peripherals. This gives the DVSS 10 a gateway to PC compatible hardware and software.

By virtue of its direct connection to the display boards 36 and its connection to all system peripherals, the control board 32 and the display board 36 software are tightly coupled. FIG. 10 illustrates the group of parallel programs that run on the controller board 32 and the display board 36. These program are responsible for controlling interface to all computers on the existing security system as well as the peripherals to the DVSS 10 such as a high resolution display monitor 28 and controlling keyboard 200. Bubble 1 of FIG. 10 represents a program to interface with the personal computer 39 and which gives Transputers in the network access to personal computer functions, such as keyboard, disks, communication ports, etc. Bubble 2 represents a display program which interfaces with the user controls, accepts keyboard codes which are converted into display control commands. This software also operates the interactive menu, to be described hereinafter. Bubble 3 represents a graphics library program which generates graphics commands for line drawing, image display, text, menu display, etc. Bubble 4 represents a control link interface program which controls bus messages, formats outgoing messages, decodes incoming messages, and directs messages to the designated boards. Bubble 5 represents a software clock which maintains system time with respect to which events are controlled and referenced. Bubble 6 represents a video link program which controls access to the video link for any of the processing boards. The display program of Bubble 2 makes video link access requests to access data and resources on other boards. Such data or resources may include images from frame grabbers and access to buffer boards. A.2. in the Appendix is a listing of the software for each Bubble which runs on the controller board 32.

The programs represented by Bubbles 2, 3, 4 and 6 are implemented on the controller board 32 and each of the display boards 36(1)-36(N).

FIG. 11 is a Bubble representation of the software which controls the digital I/O interface 41. Bubble 1 represents software for interfacing with the serial input and output devices such as fax machines, modems, alarm computers, card readers, video switches, etc. Bubble 2 represents software for interfacing with parallel devices such as text printers, image printers, etc. Bubble 3 represents software for controlling the supply and retrieval of data from the video and control links. Bubble 4 represents software for controlling the SCSI disk controller 43A. Bubble 5 represents software for communication data preparation including software for compression and decompression of data for interface with fax machines and modems. Bubble 6 represents software for decoding input data to extract necessary information from the pre-defined communications on the tapped serial communications lines of the existing security systems. A.3. in the Appendix is a listing of the software for each Bubble which runs on the digital I/O interface 41.

FIG. 12 is a Bubble representation of the software which runs on the alarm sequence buffer boards 44(1)-44(N). Bubble 1 represents software for controlling access to the video link and for multiplexing incoming and outgoing messages. Bubble 2 represents software for controlling message traffic over the control link and for multiplexing resource requests. Bubble 3 represents data management software which controls and limits access to a main image data base stored in DRAM, and interfaces between multiple requests for images from the frame grabber and display board requests via the video link. Bubble 4 represents the main image data base which is a storage area for images of an alarm sequence stored in the alarm sequence buffer in DRAM. A.4. in the Appendix is a listing of the software for each Bubble which runs on the alarm sequence buffer boards.

FIG. 13 depicts the manner in which the system software for each Transputer is loaded. The Transputer of the controller board 32 is the only Transputer which connects with the personal computer 39. Initially, in step 130, the main software file for controlling the operation of all Transputers including that of the controller board 32, is loaded from hard disk through the personal computer 39 via disk controller 43B. Once the code is loaded into the controller board 32, the Transputer of the controller board in step 132 deciphers distribution instructions to determine which portions of the executable code goes to which Transputer. The controller board 32 controls the various switches and processing boards to distribute the code to the various Transputers according to the distribution instructions in step 134.

Included within the main software file is a file called a Configuration File. The Configuration File contains a set of programmable parameters for a specific host system and DVSS 10 configuration. The Configuration File will be described in detail hereinafter.

In accessing disk storage devices, the disk controller 43A responds to disk access requests sent to it on the control link via the Transputer of the controller board 32. The command is intercepted on the Transputer of the controller board 32 which acts as a data buffer for the disk controller 43A. The access request is translated into a SCSI protocol command sequence by the Transputer on the controller board 32 and sent to the disk controller 43A. The disk controller 43A will then access the disk and perform the necessary operations. The controller board 32 Transputer will keep a record of the file locations on the disk including a description of their contents. A copy of this information will also be kept on the disk.

FIG. 14 illustrates the general functionality of the display boards in interacting with an FG/FS board. The display boards operate either in a secure mode or display mode. The secure mode is the display mode that exists when there are no uncleared alarms to be viewed. Four slow-scan, live-view images from 4 cameras at a time are shown. Each set of 4 cameras is shown for a period of time and then a new set is displayed, and so on. The first step 140 involves the selection of the four cameras for secure mode display. Next, in step 142 the display board requests that the controller board 32 access the required FG/FS board for display. In this capacity, the controller board 32 acts as a hub for video link control. Once the appropriate FG/FS board has been identified, in step 144, the display board requests, via the video link, that the desired frames of images be sent to it. The video images from the selected FG/FS board are displayed and are updated as new images become available from the associated FG/FS board. This process may continue for a specified period of time, as illustrated by step 146, and then switch to another set of cameras. However, the occurrence of an alarm event or other user interaction may override the display board into the alarm mode.

A display board may be switched into the alarm mode either by an external alarm or manual entry. In either case, the system will be notified of the zone number of interest. By way of a look-up table in the DRAM 52 on the controller board 32, the controller board 32 will determine which particular display board is connected to the camera(s) that covers that particular zone. A message is sent to the controller board 32 to switch the video link to connect the required FG/FS board to the display board directly. This is a high priority request that overrides the secure mode displays, but not other alarms. Once the connection is made, the selected display board, in step 148, sends messages over the video link instructing the corresponding FG/FS board to send images over the video link. The display board will request the image closest to the alarm first, and once it is received change the display format to that of the alarm mode. The operator will thereby be allowed to examine the alarm image while the rest of the sequence is being downloaded. A horn will sound in the keyboard 200 at the time of switching from the secure mode to the alarm mode. The display board then receives these images in step 150 and in step 152, the user is permitted to perform any of the available image manipulations functions.

The image manipulation functions include image scanning in time; saving images to disk; marking images with cause and a pointer to indicate location of interesting features; zooming in on an interesting feature with the ability to pan and scroll the field of view; adjusting contrast; transmitting images by facsimile machine or modem; printing images; etc. The appearance of the display in the alarm mode is shown in FIGS. 15A and 15B. As shown in these Figures, there is a maximum of four image areas 160A-160D (under 2 alarms) which are selectable for further manipulation, as will be explained in greater detail in conjunction with FIGS. 16-18. In particular, the image areas 160A-160D may be configured so as to display freeze frame for a primary camera in areas 160A and 160D and freeze frame for a secondary camera in areas 160B and 160C. Optionally, a slow scan live-view of the primary cameras could be substituted for the secondary camera freeze frame in areas 160B and 160C.

If additional alarms occur while already in the alarm mode, the required images will be downloaded as described above. As shown in FIG. 15B, the display board provides for two alarm displays as well as an alarm window to warn of additional, undisplayed alarms.

FIGS. 16-18 illustrate the user keyboard 200 and examples of display menus, in accordance with the present invention. The keyboard 200 is connected to the digital I/O interface 41, as shown in FIG. 2, to provide for access to the DVSS 10. The keyboard 200 comprises five sections of controls: (1) active alarm section 202; (2) options section 204; (3) contrast section 206; (4) zoom section 208; and (5) call-ups section 210. Selections are displayed on one of the monitors 28 together with a menu for the particular function selected, as will be explained in detail hereinafter.

Critical to interaction with menus displayed on the monitor is the joystick 212. The joystick 212 allows the operator to scroll up and down within a menu. It permits the user to toggle between selections for user prompts. During zoomed images, the joystick scrolls the image left, right, up and down. While using the MARK function, the joystick controls the position of the pointer in the displayed image.

In the alarm section 202, the UPPER LEFT, UPPER RIGHT, LOWER LEFT and LOWER RIGHT buttons are used for selecting between the named display window cameras. Specifically, as shown in FIG. 15B, there are four image display areas on a monitor screen. Hitting one of these buttons highlights the selected area as the active display window and all subsequent display window operations are performed on this selected camera image.

The CLEAR button is used to clear the current active alarm and to remove the alarm from the active display window. In addition, the alarm is removed from the current alarm buffer menu. If no other alarm exists, the system is returned to a wait state. Referring to FIGS. 15A and 15B, if the cleared alarm was in the upper portion of the display, it is cleared and the image in the lower window is moved into the top position. The next active alarm image will be displayed in the lower portion of the display.

The arrow buttons in section 202 are used to replace the active alarm camera image with a preceding or succeeding frame, depending on which button is actuated. Consecutive actuation of a button will step through the frames to the maximum number of preceding or succeeding frames saved. The arrow buttons become inactive once the maximum number of preceding or succeeding frames has been reached.

The RUN SEQUENCE button is used to step through each stored frame in a predetermined timing from the oldest frame to the newest frame in the sequence.

In the options section 204, there are provided buttons labelled PRINT, MARK, SAVE and RETRIEVE. The PRINT button is used to print to an external printer the image on the active display window. The MARK button is selected to lock the current image, zoom and contrast. An alarm cause menu is then brought up on the monitor and display annotation is initiated for the active display window. The alarm cause menu is a programmed list of possible causes for an alarm, and is part of the Configuration File. For example, as shown in FIG. 17, a menu of possible alarm causes is listed and by moving the joystick 212 (in zoom section 208), the user may highlight on the monitor the appropriate cause within the listed options. Hitting the MARK button a second time selects the cause from the menu and displays the pointer in the active camera on the monitor. The joystick is then movable within the display to locate the pointer to the apparent cause of the alarm. A third actuation of the MARK button locks the pointer in place and exits the display annotation.

The SAVE button is used to save images of the active display window alarm to an external disk. Once the SAVE button is depressed, the operator is prompted with the option to save the single displayed image or the entire sequence. The joystick 212 is used to highlight the desired option. Hitting the SAVE button a second time prompts the operator for specifying the destination disk. The joystick is used to make this selection and a third actuation of the SAVE button stores the selected image data to the selected external disk.

The RETRIEVE button is used for accessing images stored on external disk drives. The operator is prompted with a menu of available display files. The joystick is moved to select the desired file and a second actuation of the RETRIEVE button selects the highlighted file and prompts the operator for the appropriate source disk. Much like the prior described procedures, the joystick and RETRIEVE button are used to display the stored image in the active display window. The image will remain on display until it is replaced or the CLEAR ALARM button is actuated.

The CLEARED ALARM BUFFER button is used to bring up a list of alarm sequences which have been cleared by the operator but still remain in buffer memory. This list is appended to the current alarm list which shows all alarm events that have not been cleared. The joystick is used to select a particular alarm from the menu and the CLEARED ALARM BUFFER is actuated again to display the selected information of the active display window. This allows the operator to go back and view alarms that may have been cleared prematurely.

The MENU button provides the operator with a list of system features not directly accessible from individual buttons on the keyboard panel. Selection of each menu item prompts the operator appropriately. This allows flexibility to modify the control software to meet particular site requirements without redesigning the keyboard 200.

The QUIT button causes the current operation to be aborted and returns the display to the configuration prior to the aborted operation. Any active open menu is closed. The QUIT button is not active unless an operation is in progress.

The buttons in the contrast section 206 are used for controlling the quality of the image being displayed. The INCREASE button increases the contrast level for the entire display. Consecutive actuation of the button increases the level to a maximum of 16 times, at which the button becomes inactive. The contrast level remains in effect until modified by another contrast adjustment. The DECREASE button works in a similar manner.

The RESTORE button restores the contrast level for the entire display to a default established in the Configuration File.

The CHANGE button causes the active display window to be enlarged to the full size of the display.

In the zoom section 208, the IN button is used for zooming in on the active display window's images. When actuated once, the image is zoomed in 2 times, up to a maximum of three presses for 8 times zoom. The display will be zoomed to center unless the MARK button is active in which case the display will zoom to the pointer. Panning and scrolling with the joystick 212 is permissible in the zoomed image. While in zoom, all new images will be displayed from the current zoomed center.

The OUT button is active only if preceded by an IN selection. The images are zoomed out with actuation of the OUT button. Consecutive actuation of the OUT button moves the image out to a maximum display area, maintaining the display center. Panning and scrolling with the joystick 212 is likewise permissible as long as the image is zoomed at least one level (2 times).

The CALL-UPS section 210 includes a key operated switch 214 having a NORMAL position and a SUPERVISOR position. In the normal position, only certain types of functions are accessible whereas in the SUPERVISOR position, all functions are accessible including many from the menu which are not accessible to an operator in the NORMAL mode.

The CALL-UPS keypad is used to access directly a particular camera. Hitting any number and the ENTER button triggers a display window which shows the operator the numbers selected and initiates an alarm event within the DVSS 10 for the selected camera. The CLEAR button in the keypad removes any numbers and window from the display prior to pressing the enter button.

The following is a list of examples of programmable parameters forming the Configuration File.

Auto Cycle Speed--The rate at which images are played back when the RUN SEQUENCE button is selected.

Image Display From Single Video Input--Up to four frames can be shown simultaneously from one alarm sequence for a single camera. (Only a single camera shown in entire display.)

Alarm Window Contents--Standard alarm window contains a freeze-frame from a primary and secondary camera. Alternative configurations include a primary freeze-frame shown in conjunction with a slow scan live image.

Override/Privileged User Capabilities--In systems having multiple external controlling keyboards 200, a hierarchy can be defined allowing one keyboard to override the action of another.

Supervisor Action Definitions--Features that are restricted to the supervisor mode (key switch 214 protected) versus being available to all operators.

Default Contrast Level--The contrast level which will act as the default for the system, i.e., which contrast will be restored when the RESTORE button is selected.

Pop-Up Window Defaults--Default selections used when pop-up windows are presented to the operator (to continue or to quit).

Alarm Cause List--The list of choices an operator has for defining the cause of an alarm when the MARK button is pressed.

Transmission List--The list of choices an operator has for forwarding images directly from the system when the transmit option is selected from the menu.

Pre-Alarm Frames Per Video Input--Number of frames per video input that can be captured prior to the occurrence of an alarm. System maximum up to 63 (63 pre-alarm frames+1 at time of alarm+0 post-alarm frames).

Post-Alarm Frames Per Video Input--Number of frames per video input that can be captured after the occurrence of an alarm. System maximum up to 63 (0 pre-alarm frames+1 at time of alarm+63 post-alarm frames).

Default Alarm Display Frame--The frame from the sequence to be displayed to the operator as the default when the alarm is first displayed on the video monitor.

Alarm Overload Management--The manner in which the system responds when the alarm buffers become overloaded. Options include buffering alarms to disk, disregarding new alarms until the operator has cleared space in the buffer, or replacing the oldest alarms with new ones as they enter the system. In all cases operators would be alerted that overload management is in effect.

Zones (Number and Naming)--Defining the number of zones and providing a name which will appear on the display when that zone is "alarmed".

Camera Allocations to Zones--Defining which cameras are assigned to specific zones. Includes primary and secondary camera definitions.

Alarm Trigger--Messages from the host computer which cause an alarm to occur in the DVSS 10.

Disk Storage Devices (Number and Types)--The storage space the operator has for archiving images. Types include fixed disks (various sizes) and/or combinations of removable disks.

Printers (Number and Types)--Number of printers for outputting video and non-video (i.e. operator log) images. Types include digital thermal printers and/or wax transfer color printers.

Monitors (Number)--Multiple monitors can be connected to the system all showing the same information or individual video outputs which can be used to show different images.

Frame Grabber Boards (Number)--Number of frame grabber boards within the system. Tied to the number of cameras, the resolution and the number of frames stored per camera. Also impacts on the number of chassis required to house the DVSS 10.

Video Inputs (Number)--Number of cameras which can be connected to the system.

Independent Video Outputs--Number of high resolution video monitors 28 which can be connected to the system containing unique video information.

External Controlling Devices (Number and Types)--Number of external controllers that can influence the system. Types include the operator controlling console keyboard 200, the host alarm computer 20, etc. System maximum of 16.

Frames Per Camera--Total number of frames per camera that can be captured when an alarm occurs. System maximum of 64.

Display Resolution--The system resolution for the images presented to the operator. Options include 256.times.240 pixels or 512.times.480 pixels (normal).

Alarm Images Buffered (Number)--Number of alarm sequences that can be buffered on buffer boards 35 (i.e., waiting for operator review). Add 2 to this number for the images already on the display and 1 more dedicated buffer for each camera for the total number of image buffers available.

Frame Grab Rate--Interval between image frame grabs. System minimum of 500 milliseconds, maximum of 99 seconds. Separately programmable for each camera.

Scenario Development and Training--A number of software configurations for developing realistic training scenarios.

Loss of Video Indication--Software which will recognize the loss of a signal due to cut cables and/or loss of power.

Motion Detection Capabilities--Software which will use image comparison techniques to determine if a change has occurred between the images (motion).

Frame Grabber Parameters (Synchronization With Site)--Parameters which synchronize the system with the analog signals of the cameras. These are site specific and not likely to be modified unless the connected cameras change. ##SPC1##

It is to be understood that the foregoing description and accompanying drawings set forth the preferred embodiments of the invention at the present time. Various modifications, additions and alternative designs will, of course, become apparent to those skilled in the art in light of the foregoing teachings without departing from the spirit and scope of the disclosed invention. Therefore, it should be appreciated that the invention is not limited to the disclosed embodiments but may be practiced within the full scope of the appended claims.