PATHFINDER VIDEO MOTION DETECTOR
WHAT OUR EXPERTS SAY...
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
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
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.
SETUP AND OPERATION
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
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
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