to video capture and
by Joe Janson,
Project lead at Omega Unfold Inc
have a motion detection project, what do I need to know?
A motion detector
systems can give your PC eyes, letting it respond to external events by
capturing images, or triggering actions. However, there’s a bewildering array
of possible set ups, not all of them useful to you. You need to
carefully identify your needs, and then get tools that are
good enough without being too much... overkill can kill your budget!
You'll require both
hardware and software. You’ll also need advice, because motion
detection and video capture are still emerging technologies and might
not be as "plug & play" as you would like. Hopefully, the
following will help you get started….
"I need my
computer to be able to see...
does motion detection software
software captures video from an input device and processes this video
in real-time to find significant changes between frames. How it
responds to these changes depends on what you’ve programmed it to do.
Historically, most serve complex security systems and require special
equipment. However, general
purpose motion detection software like Zone Trigger is now
General purpose motion
detection is intended for the ordinary users and moves motion detection
away from its original security context, bringing it to new places
where it can be used to interact with people, automate processes, and
replace costly custom hardware with simple non-intrusive monitoring.
For example, the
following applications show how general motion capture can reduce
costs, increase quality or enable something that wasn't possible before:
see, not just act like a glorified VCR."
- Monitor the
state of boxes on a shelf using a single standard camera rather than
many specialized sensors.
interaction with clients viewing a conference stand by using a
multi-zone motion detection.
- Achieve a
new level of audience immersion by adding motion detection to an
flow through your bricks and mortar store by monitoring motion through
Good general purpose
motion detection software should let you determine exactly what kind of
motion to look for and then permit a range of responses, e.g. taking
pictures, recording videos and sending e-mail notifications. The best
software should also be able to analyse the movement itself. Typical
This is the simplest and most versatile technique. The software looks
for anything that is different from one video frame to another. It
compares pixel color and brightness (chrominescence and luminescence)
without trying to identify anything. It can be trigged by moving
objects, lights on/off, shadows, and even vibrations.
motion detection techniques, the software goes one step further and
finds the general flow of motion within the video.
The software tries to match the input image to a reference image.
and animators also use software that supports motion tracking in a
controlled environment. Future advances in hardware and software may
make this viable “in the wild”, along with routine gesture recognition-
something with a myriad of possible applications.
kinds of cameras work for
USB cameras, usually called
“webcams”, are the quick and dirty solution to hooking a camera to your
PC. All you need is the supplied driver software, so you can
be up and running in minutes. Better yet, USB cameras are Direct-X
compatible and work with almost any video capture software.
there are snags. Though you can connect lots of webcams to a single
computer, they’re more or less limited to arm’s reach because a USB
cable is not designed for distance.
More importantly, USB
cameras vary in quality. Cheap ones don’t always provide clear or
accurate images. Artefacts (visible
defects) include motion blur and oddness caused by compressing
the image before sending it to your PC. Some also do badly in poor
light conditions, providing grainy images and low frame rate.
good news is that some good quality USB cameras have a high resolution
and fast frame rate video. Some even come with zoom lenses (note that
an automatic variable focus lens is not desirable as it may introduce
movement when auto-focusing). Video
resultion varies greatly depending on the model, from standard 320x240
to "doesn't fit the screen". Don't let this amount of pixels be your
only guide for judging the quality of a camera; The price
of the camera is your first clue about the quality of its images.
DV cameras – the DV stands for
“Digital Video” - are the high-end solution. Often called “camcorders”,
these provide awesome image quality and a fast frame-rate. They are
almost always equipped with a zoom, and may have nice
features such as night-vision. Compatible with Direct-X, they should
work with most any recent video capture software.
USB cameras, DV cameras are tied to your PC by cable length, this time
Fire-Wire (IEEE 1394). However, the main downside is that
cameras (“network cameras”)
IP cameras, often known as “network
cameras”, are more complex remote-controlled devices that connect to a
network instead of directly to your PC. Since they are digital, some
can supply very high-resolution images, often with superior image
IP cameras are not
physically tied to your PC since they can broadcast video over a local
network (CCTV) or the Internet. Most have embedded web-servers, and
some have internal motion-detection systems. You can also find wireless
IP cams that will connect directly to your Wifi network.
Network cameras can be
expensive, costing about the same as camcorders. Usually lacking
Direct-X drivers, they rarely work with motion detection software
unless it specifically supports them.
usually recommend Axis IP
as they use a standard
http protocol, and some models even have
optionnal Direct-X windows drivers for optimal compatibility. Zone
Trigger has been tested with Axis and Foscam network cameras.
Analogue cameras belong to a whole
different world. They are fast, provide images with no compression, no
artefacts, no motion blur, and use any cable length you need. They may
be equipped with a zoom or infra-red vision. Some are even “wireless”
(but watch the reception quality, since local interference might
The downside of
analogue cameras is that they are complicated and resource-intensive.
Connecting one to a PC requires video capture hardware. In operation,
this can hog the system resources, so your PC probably might not be
able to do anything else! Many analogue cameras produce
interlaced images, requiring special – often 3rd party – software
filters, which may introduce artefacts or reduce picture quality.
Overall, using an analogue camera requires a more powerful computer
than a standard USB camera would.
The compatibility of
the motion detection software is dependent on the video capture device.
Here are a few capture device
are good conditions for motion detection?
- TV capture cards:
These turn your PC into a TV -tuner and DVR, and usually have inputs
for external devices such as cameras. Most are compatible with
Direct-X, but not all software has options to control channels and
Zone Trigger can use them.
- USB video capture dongles:
These are easy-to-use connectors enabling you to plug your analogue
camera into a USB port. This is great because they are portable, can be
used on laptops, and you can have several connected to the same PC. As
for TV capture cards, not all software will be able to use them
properly. Make sure to select the correct signal from the settings (PAL
/ NTSC) Webcam
Zone Trigger can use them.
- Multi-channel cards:
These support between 4 and 16 cameras at the time, and vary in quality
and price. Unfortunately, at present there is no standard for software
compatibility. They are usually not Direct-X compatible, meaning that
you are probably stuck with the bundled software.
In the best conditions you must have the following:
is Zone Trigger, and what can it bring to my project?
- A well
fixed camera - stability is key if you want to isolate motion!
light, no flickering.
background - white objects against white background might not produce
- High camera
frame rate and resolution. It goes without saying that if you want to
detect a race car, you'll need a fast camera. The motion detection
process can only be as good as the input images. If your motion
detection needs are simple, than a low-end webcam might be sufficient.
software series is all about enabling anyone to incorporate motion or
sound detection in their custom projects. The Zone Trigger softwares
can be downloaded and installed in a few seconds. It’s so simple to use
that you can set up a custom system within a matter of minutes.
On detecting motion,
Zone Trigger can do almost anything: play sounds, run programs or
commands, take control of other software, send email and files over the
internet. Plus it has many extra features such as an HTTP server and
Zone Trigger saves you
time, money and effort:
information has shed some light for you on the various technical
aspects of motion detection and video capture.
technical skills required, no development time needed.
- No costly
or complicated custom hardware to install.
support and advice to get your projects done.
solution for most interaction and automation scenarios.
Good luck with your project!
- Motion Detection software download site, download a trial
copy of the Zone Trigger software.
- Tips and examples for motion detection projects
- Network cameras
If you have questions about the Zone Trigger products or if you require
consultation and advice on your computer vision projects, please
contact Omega Unfold's technical support: email@example.com
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