Security Installer

HomeSoftwareArchiveTop TipsGlossaryOther Stuff





Video motion detection (VMD) has become something of a black art with many varying claims made for its effectiveness. However whilst our eyes and brains can discriminate between innocent natural motion Ė trees blowing in the wind, sudden changes in lighting level, shadows and small creatures -- and genuine targets, in a fraction of a second, itís a fantastically difficult feat for a machine. Even powerful, state of the art supercomputers can get into trouble, so what new slant does the Visimetrics Pathfinder bring to the proceedings?


Itís obviously not a supercomputer but it is a stand-alone unit, which is unusual. Video motion detection systems are normally integrated into other video surveillance devices, such as multiplexers and recorders, this one is housed in a slim rack mountable case, and one of the first things you notice is the absence of any controls and just a handful of LED indicators on the front panel.


Thereís not a lot to see around the back either, just a bank of BNC sockets for video input, loop-through and monitor displays, each with a simple jumper/shorting link for setting termination. Thereís a screw-terminal for alarm connections, a 9-pin D-Sub serial port and a standard DC supply socket (a 12 volt mains adaptor module is supplied). Two versions are available with 2 and 4 camera inputs; our test sample was the 4-channel model.


Needless to say all is not as it seems and thereís plenty going on behind the scenes and key features include variable sensitivity, zone masking using a 32 x 32 target grid, visible target overlay, camera sequencer/alarm display, separate relay alarm outputs for each channel and the unit can be set to temporarily ignore Ďmovementí when using PTZ cameras. The front panel indicators show power on, connected cameras and alarm triggers.



As the lack of controls suggests Pathfinder can be used straight out of the box without any configuration, though it is unlikely many installations can operate reliably on the default settings, in which case it is necessary to access the unitís configuration settings. Thatís where the serial port comes in, access to Pathfinderís inner workings requires a PC, typically any Windows PC but it must have a standard serial port connection, which, itís worth pointing out. Is becoming increasingly rare on recent laptops these days.


The access software, called Pathfinder Terminal, is supplied as a compressed Zip file on a 3.5-inch floppy disc (so make sure you have an unzip utility like WinZip on your control PC). Once the file has been extracted Pathfinder terminal can be launched and the first thing it does is attempt to communicate with the Pathfinder, which may entail editing the Com Port settings. Once the link has been established the current settings stored in the unit are read and displayed on a simple dialogue box display with five function buttons. From left to right they are Read Settings, Write Settings, Load Defaults, Connection and Mask Editor.


Read Settings is divided into two areas, the top half of the screen shows each of the camera channels, with the facility change the name or title for each camera, (only shown on the PC display). To the right of each camera thereís an enable/disable tick box, and two value adjustments for setting Minimum Object Size in pixels (from 1 to 4096, default 15), and Consecutive Frames (0 to 32767, default 3). The latter specifies how many frames of video a moving object must appear in before it is deemed to be a genuine target. Between them (Minimum Object Size and Consecutive Frames) can be used to accurately eliminate many predictable and naturally occurring false targets. The lower half of the Read Settings box is called Hold Times and is used to adjust various alarm timing parameters, including video on, relay on, alarm LED on and target box display.


The Write Settings button sends the revised data back to the unit, Load Defaults restores factory settings and the Connection button brings up dialogue boxes for changing Com settings, reboot the Pathfinder and disconnect the PC. The Mask Editor button launches a simple graphics utility that allows the user or installer to mask selected areas of the image. However, the editor box is initially blank and a low definition still is loaded into the frame by clicking the Read Mask button. Clicking New Mask on the drop-down menu changes the cursor into a pen icon and areas of the screen can be defined. The utility also contains a small selection of drawing tools, for defining square and circular shapes, and to fill them in. When the masking is complete all that remains is to click the Write Mask button to update the Pathfinder. The well-written instructions helpfully point out that zone masks should not be set for PTZ cameras, along with lots of other useful tips for camera positioning and configuration.



Video passes more or less straight through the Pathfinder, the only significant change occurs on the Overlay output, which superimposes a white Ďtargetí square on a moving object, and tracks with it as it travels around the screen. The system can only cope with one moving object per channel, which could be an advantage, or a drawback.


Target acquisition and tracking is generally fast and accurate but ultimately it depends on the quality of the image and the care taken in setting it up. Nevertheless, for simple situations Ė detecting movement in normally unoccupied areas, corridors and perimeters etc. Ė it may indeed require little or no configuration.



Pathfinder doesnít add significantly to the science (or witchcraft) of video motion detection, nor is it terribly sophisticated but it sufficiently flexible to allow a skilled installer to disregard a very high proportion of false alerts. However, the key selling point has to be that it is an exceptionally easy way to incorporate VMD into, or upgrade an existing installation.



Design and design features                      ***

Circuitry and components                ****

Ease of installation and wiring            ****

Range and variety of functions            ***

Accompanying instructions              ****                          

Technical advice and backup            ??

Value for money                         ??                          



R. Maybury 2002




[Home][Software][Archive][Top Tips][Glossary][Other Stuff]

Copyright (c) 2005 Rick Maybury Ltd.