Surveillance system adapts to security needs

By R. Winn Hardin,Contributing Editor

Inexpensive, customizable, flexible surveillance system integrates commercial and custom vision components and software for fast and easy installation.

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Thanks to improved capabilities in image-processing software, local-area networks (LANs), and wireless data communications, surveillance equipment and system developers are including more than the standard set of closed-circuit television cameras, networked alarms, and vision-based automated motion-detection systems. For example, Windermere-HDS Inc. (Reston, VA) has been developing a modular Teleport surveillance system for military and law-enforcement agencies since 1994 (see Fig. 1). This system uses off-the-shelf cameras, transmitters based on PC/104 form-factor motherboards, frame grabbers, wireless modems or LAN connections, custom and commercial software, and image-compression coder-decoders (codecs) to deliver a range of surveillance functions.

According to Bob Pozgar, president of Windermere Information Technology Systems, "The Teleport system provides government, military, law-enforcement, and commercial agencies with an inexpensive and fully customizable system for remotely monitoring any given area based on individual application requirements and needs." Custom-made surveillance configurations designed with ease-of-use in mind mean that developers can quickly and easily install and tailor the system to specific security needs.

Since the 1970s, when Windermere-HDS Inc. (then HDS Inc.) began designing and developing advanced communications systems and image- and signal-processing equipment for government, commercial, and broadcast applications, the company has focused on flexible surveillance systems that deliver increased functionality.

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FIGURE 1. The Teleport surveillance system can use a wireless modem connection, a public switched telephone network (PSTN) connection through a Hayes-compatible modem, or a LAN/Ethernet connection depending on whether a cable can be run between the transmitter PC and the receiver/central PC. Covert operations may preclude the cable option, leading to wireless connections. Generally, the system supports only one pan/tilt camera per system. The OPAL optoisolator card provides eight outputs to control camera pan/tilt/zoom, in/zoom, and out/focus.

Today, military and law-enforcement agencies often call Windermere-HDS with a vague set of requirements. Specifics of the applications are often hidden, even from the surveillance system manufacturer, explains Philip Greffe, senior software engineer at Windermere-HDS. "For example, one agency needed a low-cost means of remotely monitoring a given area to detect and report the presence of personnel and air, land, and sea vehicles. This system had to be concealible, operate in daylight or nighttime, and function reliably under adverse weather conditions. Moreover, the system had to be installed and maintained by personnel with little training and operated unattended for up to 30 days. Further, it had to operate in different modes, such as monitoring the border between two countries or as a perimeter early warning system for agency installations, facilities, and deployments," Greffe adds.

WAREHOUSE MONITORING

For monitoring a warehouse, four off-the-shelf NTSC video cameras were cable-connected to the Teleport transmitter. According to Windemere-HDS system architect Dave Weiblen, almost any CCD camera will work with Teleport, such as a standard video camera from Sony Electronics Inc. (Park Ridge, NJ), a board camera from Csi/SPECO (Amityville, NY), or a low-light intensified CCD from Proxitronic (Bensheim, Germany). The transmitter can be located up to 400 feet away from the cameras. An Imagenation Corp. (Portland, OR) PCX 200 color frame grabber in a miniature PC/104+ form factor is used to accept up to four NTSC or PAL video inputs at resolutions of either 768 x 576 or 640 x 480 pixels. The frame grabber plugs into an Ampro Computer (San Jose, CA) LittleBoard P5X motherboard with a PC/104+ bus. This motherboard contains a 266-MHz processor, quad-serial and parallel ports, USB and SCSI interfaces, a VGA controller, a 10/100Base-T Ethernet LAN interface/port, and 32 Mbytes of DRAM.

Also connected to the PC/104+ bus is a Diamond Systems Corp. (Palo Alto, CA) OPAL-MM optoisolator and relay digital input/output (I/O) card with eight inputs and eight outputs. This card provides an input interface for a range of sensors from door and window alarms to infrared (IR) and seismic sensors, and output controls for pan/tilt servos from manufacturers such as Quickset (Northbrook, IL), as well as gain, zoom, and other camera controls. Lastly, a Toshiba America Inc. (New York, NY) 6.5-Gbyte hard drive stores the Teleport transmitter Windows 95 programs and provides temporary storage for user-defined functions, such as alarm-trigged snapshots and up to two minutes of live video prior to an alarm trigger.

MOTION DETECTION

According to Dave Weiblen, military installations where the US government owns the facilities usually make use of the 10/100 Base-T LAN port on the Ampro motherboard or connect a Hayes-compatible modem to the serial port. However, in many law enforcement or covert surveillance operations, cables cannot be installed. In this case, Windermere-HDS suggests the use of wireless modems from suppliers such as FreeWave Technologies, Inc. (Boulder, CO) and Metricom Inc. (Los Gatos, CA). According to Weiblen, FreeWave's wireless modems provide 56-Kbit/s transmission. Given this limited bandwidth, Weiblen says that users can make some trade-offs by means of setup screens on the Teleport graphical user interface (see Fig. 2).

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For example, the Teleport system uses the Summus Ltd. (Raleigh NC) wavelet compression algorithm with several preset compression ratios: 1:1, 50:1, 100:1 or 200:1. Greffe says that Windermere-HDS has found that wavelet-compression offers the best compression and transmission speed functions as well as picture quality after decompression. Summus uses a variation of the Haar transform to reduce the image data based on the average value between the same pixel in sequential frames and the difference of those pixel values. By repeating the transform—averaging and subtracting the values from one level to the next—the data size can be greatly reduced while providing a decompression path to the original values. Of course, the higher the compression ratio, the more image information is lost (fuzzy pictures) during decompression.

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FIGURE 2. The MASK pushbutton on the Teleport graphical user interface initiates a dialog that allows the user to set the cameras' inclusion/exclusion zones (top). It depicts the same video image and allows the drawing of inclusion/exclusion zones using typical Windows drag operations. Contrast and noise settings permit adjustment of the alarm to minimize ambient motion such as the rustling of leaves. Among noise, contrast, and filtering, the user can set the VMD (video motion detection) pushbutton to detect larger movements such as those made by people (bottom).

The user also has several preset frame sizes to choose from, starting with full frames (512 x 384 pixels) to thumbnail frames (88 x 66 pixels). Frame-size adjustments are programmed at the Teleport receiver/ central PC and implemented on the Imagenation frame grabber. These adjustments are the only processing function that the frame grabber performs, says Weiblen. The central PC used can range from a rugged x386 type to multiple Pentium designs, as long as the PC has a modem compatible with the transmitter, or a network interface, and the Teleport transmission software.

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Several years ago, users were given wide discretion in setting values such as compression, frame size, and frequency of "snapshot" images. As Greffe explains, "Feedback from military operators suggested that fewer options would make surveillance system installation and operation easier. The Teleport system offers a range of features and options that tended to overwhelm the technical limitations of the system user. These users prefer a system that can be installed quickly and made operable with minimal training and skills. To that end, we did things such as automating alarms and snapshots. We eliminated the ability of the user to specify unlimited values for various parameters and implemented selection lists with preset values. Initially we allowed the user to resize the video window much like you do with any window under Windows 3.1/95/98/NT. The user didn't like that variability though, so we implemented four standard sizes that they select via a pushbutton."

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FIGURE 3. The Teleport surveillance system detects motion in a camera's field of view by detecting sharp changes in pixel intensity values (top). A sudden change prompts the system receiver to send an alarm or a snapshot, or store recorded video based on preset parameters. Up to 32 regions of interest, with exclusive or inclusive zones can be set within a single camera's field of view (bottom).

At the system receiver end, the user selects such parameters as frame size, scheduled snapshot storage, and length of video storage. A key benefit of the FreeWave wireless modem is that it can be used to set up a wireless network with one reception node that works with multiple transmitters. Other wireless modems do not have this ability for multiple wireless transmission nodes.

Additionally, the Teleport system offers a video motion detection (VMD) capability (see Fig. 3). If the user activates the VMD function for a particular function, the Teleport transmitter software sends an alarm message when pixel values from a single camera vary beyond the preset limit. According to Greffe, "The limit varies according to numerous variables such as contrast setting, applied filters, and noise ratio. These values can be set by the user to fine-tune VMD for particular installation requirements. The system works equally well with color, gray-scale, nightvision, or infrared conditions."

The VMD capability is conducted on the Ampro motherboard through the Teleport transmitter software. The user at the receiver PC can program up to 32 different regions of interest or zones within a camera's field of view, 16 inclusion zones, such as around doors or desks, and 16 exclusion zones, such as a window, tree, or fence, where winds could trigger an alarm. Exclusion zones can be placed inside inclusion zones to further define the areas of interest.

SMALL FOOTPRINTS

Future surveillance system developments at Windemere-HDS are geared at reducing the size of the hardware and software footprints and lowering costs and power requirements. "Teleport will benefit from the continued growth of capability in off-the-shelf components," Greffe says. "Computers are becoming much faster, which improves performance without any effort on our part. Cameras are becoming cheaper and have better resolution and low-light capability than before, again improving system cost and performance without any effort on our part. Our latest efforts are to make the transmitter smaller, cheaper, more rugged, and consume less power, and these efforts, too, are the results of changes in the components rather than in any radical design efforts on our part. We continue to look for improvements in video image compression because that affects the rate of video transmission and image quality. Our goal is to make Teleport a commercial off-the-shelf product."