Not many years ago, video motion detector (VMD) technologies were receiving a lot of attention from the sharpest electronic security developers. Outdoor motion detectors were especially in vogue, with prestigious groups such as Sandia National Laboratories conducting tests for their suitability in protecting our most sensitive national security sites. Single- and multi-channel suppliers were numerous, and many major CCTV manufacturers carried at least a private-label version of a VMD.
A review of the VMD category at the recent ISC West event in Las Vegas indicates a robust number of VMD suppliers (83 companies listed), but only a handful are dedicated VMD manufacturers. What happened? What caused this upheaval? The answer is one word: integration.
Motion detection is arguably the most integrated technology in video today. It is included in almost every alphabet-soup surveillance solution—DVRs, DVMS's (digital video management systems), and IVS's (intelligent video systems) are just a few. How did we get here, and what is the impact upon users and their security solution options?
Two major factors drove the increased integration of VMD:
1) The initial technical shortcomings of the DVR, and
2) Mother Nature's ability to outfox the smartest engineer when it came to outdoor reliability.
The DVR Factor
When they were first introduced, DVRs were expensive and offered limited storage. The first DVRs using high-speed, high-cost, low-density disks could only compete effectively with tape technology if we could somehow minimize the amount of space required to store quality digital video.
Engineers found two obvious solutions to this problem: integrate outside alarm devices with the DVR, or record via a time schedule. These techniques would restrict the continuous recording that would otherwise burn up the disk space. Somewhere along the line, a very enterprising engineer realized that if we only recorded when a camera “saw” activity or movement, then we could both guarantee capture of desired scenes and conserve expensive and limited storage space.
Technological advances have now almost eliminated disk size and cost as a factor in recording capabilities, but motion detection still holds its own as a security-enhancing, space-saving feature.
Mother Nature's Impact
The second driving force in the rapid integration of motion detection into other products has been the effect of Mother Nature on outdoor applications. We should note here that even the most rudimentary VMD works well indoors, where environmental factors such as lighting, shadows, and unusual movements can be controlled rather easily. In areas such as warehouses, indoor motion detection may even be considered for a primary detection technology. Outdoors, however, is a different matter.
Having been involved with some of the most advanced (and expensive) VMDs of their time, I can attest to Mother Nature's success in defeating the most complex algorithms. Moving shadows from cloud formations, moving shade areas under trees, reflections from snow alongside a plowed roadbed … all of these can result in the most sophisticated VMD being ignored as a false-alarm generator in very short order.
Integrated Solutions Enable Outdoor Use
While storage capacity is no longer an issue, Mother Nature is still the bane of most outdoor VMDs. The good news is that many integrated motion detection products can assist today's security professional in taming Mother Nature's impact. The bad news is that it will require some research and comparison to identify the best mixture of features to apply to each application. However, there are some common options that any responsible security professional can consider when it comes to outdoor applications.
As early as the mid 1990s, perimeter protection experts recommended that VMDs be used in conjunction with other alarm technologies in “gated” alarms. This technique required two different technologies (say a VMD and a fence-mounted sensor) to alarm within a pre-set time window to actually trigger an alarm to an operator.