Key Considerations for Designing an IP Video System
- By Paul Bodell
- Dec 01, 2009
Many video systems today do not provide the image quality that
customers seek. More often than not, this is because integrators
and consultants are not taking the time to discuss desired system
requirements with their end users.
Recognizing that you need surveillance video is step one. Identifying
what type of video you need -- and there is a wide range --
is the next step and can be the difference between satisfaction and
frustration. A few considerations will enable you to get a system
that meets your expectations without breaking the bank, but first
you have to get realistic and separate wants from needs. Here are
five considerations that, when addressed properly, may satisfy the
end user.
Why do you need surveillance video? Do you want it simply as
a deterrent, or do you really need to identify people? Answering
this question correctly will let you identify what image quality
you need.
If you know the suspect’s identity and simply need to catch
him in the act, a video system that provides general surveillance
image quality should suffice. If you need to identify a stranger,
differentiate two similar people or read a license plate, you need a
video system that will provide a higher level of forensic detail.
Where do you need surveillance video? While most end users
want to cover every square inch of their facility, it is unlikely they
have the budget for that. You may want to read the registration
sticker on a license plate but really only need to read the numbers
on the plate. Choosing correctly will mean the difference between
installing too few and too many cameras.
Will you be monitoring video or using it to identify events? This
will help determine if you need fixed or mechanical PTZ cameras.
If you have people watching the cameras 24/7 and don’t expect
multiple events to happen or multiple people to enter the surveillance
field at the same time, then PTZ cameras can be effective in
covering a large area with a single camera. If the cameras are not
manned 24/7, then it’s likely you will miss critical events.
What frame rate do you need? Few people take the time to
think about this. Consider that the eye cannot tell the difference
between video that is higher than 20 frames per second. So, do
you really need 30 fps? Blu-ray quality video is 24 fps but most
people can easily watch a 5 fps video. When you consider that 10
fps video systems will eat up twice as much storage as 5 fps, then
you might not mind a little bit of choppiness in the video.
How long do you need to keep video? Usually this depends on
how long before you discover something has happened and need
to investigate. If you are trying to catch vandals spray painting
your dumpster, how long will it be before you see the spray paint?
If you won’t see it for three days, then four days of storage should
be enough. There is no need to ask for a video system that will
record and store for an entire week.
Think about your needs of a video system to accomplish
surveillance goals before contacting the integrator. You increase
the chances of getting a video system that satisfies your needs
and budget, while saving the integrator a lot of time. A quality
integrator will take the time to assess the facility, business and
security needs and ask if you need general, forensic or high detail,
how fast subjects will be moving or where the critical entry/exit
points are.
The experienced integrator will know that general surveillance
requires 10 to 20 pixels per foot, so the general surveillance
camera will need a wide-angle lens and at least 2,000 horizontal
pixels, which is what a 3 megapixel camera delivers.
Depending on what type of activity the end user is looking
to capture, generally 2 to 10 fps will provide more than
enough video. The more images wanted means the more storage
needed. Four days of storage with only 50 percent activity
is actually only 48 hours of video. For example, a 1.3 megapixel
camera recording at 2 fps requires less than 30 GB of storage
for 48 hours -- equivalent to the amount available in compact
flash today.
For the second camera, the integrator knows that forensic detail
is at least 40 pixels/foot and they need to cover a 32-foot wide
entrance/exit. The end user will need 1,280 pixels (40x32) for that
camera -- a 1.3 megapixel model. Since cars will be traveling at
20 miles per hour, each will pass through the field of view in 1
second, and if you want five forensic detail images, then you need
to run that camera at least at 5 fps.
Using a frame rate that captures what you actually need instead
of the usual default of 30 fps substantially reduces storage costs.
Once you find an integrator you feel you can trust, ask
them to provide test shots of your facility and the surveillance
area target fields of view. Since the project will require several
thousand dollars, this is not asking too much. A short video
clip of a car driving through your lot should be part of the bid
process so the end user knows exactly what quality of images
they are getting.
When evaluating and purchasing a video surveillance system,
be sure to invest not only money but time as well. Be certain to
identify needs by using proven metrics, such as pixels per foot
and frames per second. Make sure to discuss these needs clearly
with the integrator. The resulting video surveillance system
will not only fit within a desired budget, it will meet and likely
exceed all expectations.
This article originally appeared in the December 2009 issue of Network-Centric Security.
About the Author
Paul Bodell is the chief marketing officer at IQinVision.