Why Your VMS Matters
Interest in hemispheric cameras is a result of saving money
- By Bret McGowan
- Sep 01, 2017
As a security professional, how
many times have you had to
explain why a PTZ camera
should always be paired with
at least one fixed camera to
provide constant “back-up” coverage of everywhere
the PTZ is not looking?
Today, that conversation is happening
far less often, thanks to the current generation
of hemispheric cameras—super highresolution
360-degree cameras with fisheye
lenses. For many PTZ applications, as well
as situations requiring the use of several
fixed cameras, a single hemispheric camera
is now often the preferred solution. However,
in order to take full advantage of the
benefits offered by hemispheric cameras, you
must carefully consider the VMS being used
with them. Understanding the relationship
between VMS and camera is vital to ensuring
that your investment in this technology
delivers on expectations.
Why and Where?
The main reason customers are so interested
in hemispheric cameras is that they can save
money. Investing in a VMS system can add
up quickly, and an easy way to keep costs
contained is reducing camera count. Using
a single camera to cover large areas reduces
costs in many ways: the price of cameras
themselves, cabling to support them, and
the associated time required for installation.
There are also cost savings related to VMS
licensing (only one camera license is needed,
instead of several) and on-going maintenance
Hemispheric cameras are popular in
a wide range of settings, both indoor and
outdoor. Schools use them in intersecting
hallways where multiple cameras were historically
installed. They also make sense in
large spaces that have a defined perimeter,
like cafeterias and gymnasiums. Commercial
customers find them useful in areas such as
lobbies or parking lots. To cover these spaces,
the cameras can deliver a wide, 360-degree or
180-degree view, and allow for zooming into
specific areas as needed.
Usually, they are ceiling or wall mounted,
with the main difference being that a wall
mounted camera can only provide a 180-degree
view. When wall mounted, a “wedge
mounting plate” is typically used, that tilts
the camera downward, so that its field of
view covers the length of the wall. A less
common mounting option is facing upward,
either on the floor or on a table or counter
top. In all situations, the compression and
data rates are the same.
When choosing how many megapixels
you need, keep in mind that the megapixel
count refers to the entire field of view—all
360-degree or 180-degree. Bandwidth and
storage will need to accommodate that number.
However, when you zoom in on sections
of the total image, your megapixel count
for that video frame is approximately equal
to its percentage of the entire field of view.
And, the more you zoom in, the lower the
visual megapixel count becomes. So, if you’re
thinking about using one hemispheric camera
in place of four 2MP cameras, you will
need at least an 8MP hemispheric to deliver
images of each quadrant with a similar level
Does Your VMS Dewarp?
When hemispheric cameras first entered the
market, several years back, the VMS systems
on the market hadn’t been designed to
deal with them any differently than “regular”
cameras. Therefore, the hemispheric
cameras were responsible for dewarping the
distorted image captured by their fisheye
lens before sending it on to the VMS. This
meant that the VMS recorded the video exactly
as it was displayed. Full information
available from the original spherical image
was not captured.
Today, many VMS manufactures are
building dewarping filters into their own
software. This allows the VMS to receive a high-resolution image of the camera’s entire
field of view, and then display it in any number
of ways. Better yet, it can provide these
multiple views simultaneously. For example,
a VMS might be set up to display video from
a single hemispheric cameras in several different
- Panoramic frames can display the entire
perimeter of a property using just two
- Zoomed in frames displaying certain areas
of interest, set up as presets, as if each
were an individual camera. Such areas
might include doorways, cash registers,
service counters, kiosks, etc.
- A virtual PTZ experience, very much like
using a real PTZ, that allows for panning
and zooming around the original 360°
spherical image. Although the zooming is
digital, today’s 6 and 12MP cameras have
come a long way to diminish the pixelization
that can occur.
That a single camera can do all of these
things, simultaneously, is pretty remarkable,
but the fact that it can do so both in live view
and playback mode, completely independent
of each other, is what really sets the power of
these cameras apart. For example, let’s say
that a hemispheric camera is being used to
cover a parking lot. A car on the lot was vandalized.
When the damage occurred, system
operators did not have a close up of that particular
car set up in their live viewing streams.
No problem. With a hemispheric camera
covering the entire lot, and a VMS dewarping
the video, the system operator can set up a
video frame that focuses just on that car and
the surrounding area, after the fact, and then
view it in playback over the time in question.
All the visual detail was captured by the VMS
as part of the original, high-resolution video
stream sent from the camera.
In other words, having a hemispheric
camera with VMS dewarping is like having
the ability to instantaneously install a new
camera whenever you need it, without any
labor or the hassle of configuring or focusing
it, and then view video from before it was
“installed.” Now that is cool.
No Solution is Perfect
While hemispheric cameras break new ground
in many ways, there are still situations where
traditional cameras work better. The most obvious are situations that require super high
magnification. The clarity of optical zoom offered
by traditional PTZ cameras across long
distances far surpasses anything that can be
delivered by the digital zoom of today’s highest
resolution hemispheric camera.
Angle and perspective should also be
considered. A hemispheric would not work
well as part of an LPR system, which needs
to read plates from a camera mounted down
at car level.
Lighting can also be an issue. Hemispheric
cameras with fisheye lenses do not perform
well in low light or uneven light, so for those
conditions, it’s better to seek out a different
camera option, or to invest in additional
lighting to brighten the area.
Finally, hemispheric cameras with very
high megapixel resolutions are growing in
popularity, and with these high resolutions
(6MP or 12MP) come the need for greater
bandwidth and storage. Also, decoding and
viewing such high resolution video streams
requires a lot of a PC’s CPU power, so there
is a limit as to how many of these cameras
can be simultaneously viewed within a VMS.
Hardware and network requirements, and
associated costs, to support high-resolution
hemispheric cameras need to be evaluated
against the cost savings and benefits of using
fewer cameras overall.
Hemispheric cameras are growing in
popularity for good reason. When paired
with the right VMS, they can save customers
money and provide excellent coverage, while
delivering capabilities and flexibility not possible
any other way. Just make sure that you
choose a camera that offers high enough
resolution to support your zooming requirements,
and a VMS that can process the image
at the required resolution and frame rate,
dewarp it, and allow for setting and calling
up presets of your desired views. If all those
boxes are checked, you can feel confident
that your hemispheric cameras will provide
added value and enhanced performance to
your surveillance system.
This article originally appeared in the September 2017 issue of Security Today.