Oh, The Pressure!

With today’s video technologies continuing to rise in complexity and cost, the pressure of making the right decision… well… The “pressure” here is not the pressure of decision, it is the decision of pressure.

Decision: A pressurized outdoor camera or a sealed outdoor camera (non-pressurized)?

Why have pressurized cameras?

Typically, the location of the camera will be in an area that is known to have some type of air-borne contaminants that could damage the internals of the camera. Contaminants can be anything from oil, water, or any particulate matter from manmade or natural occurrence. The thought here is that if the camera is internally pressurized above ambient pressure, these contaminants will be prevented from entering.

The core purpose of pressurization in an outdoor camera is to “ensure that no water, moisture or dust is able to enter the camera enclosure and cause premature failure of the electrical, mechanical or optical components.”

The above quote was taken from a previous blog entitled “Dry As A Bone” in describing the challenge of building an outdoor camera; to read the entire article click on the link below:

http://gotowti.typepad.com/my_weblog/2009/09/something-sidewinder-related.html.

The manner in which the seals are created for the Sidewinder P/T/Z camera is the same manner in which the seals are created for the all fixed cameras manufactured by WTI. A sealed outdoor camera (from WTI) meets the same core purpose as that of a pressurized camera; contaminants are prevented from entry.

Consider the maintenance cost reduction benefit of a sealed camera: no pressure checks! (Also, no alarm conditions when internal camera pressure drops)

Consider the installation site. Underwater (sea floor monitoring) or extreme altitudes (weather balloon) will indeed require some type of pressurized camera enclosure. Highways, intersections, utility infrastructure sites, building perimeter, etc… Why have pressurized cameras?

~David Scales, C.T.O.

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WTI (Wireless Technology, Inc.)

Video Surveillance Products Dedicated to the Broadcast, Global Security and Transportation Markets!

www.gotowti.com ● www.wirelesstech.com

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Thermal Imaging : Nowhere to Hide!

All over the world thermal image technology is being utilized in conjunction with traditional CCTV surveillance systems to keep watch over vulnerable areas after dark.

What makes thermal image cameras so unique?
At night there is not a lot of visible light nor enough contrast for a camera to work with so most surveillance camera images will be too dark to make anything out. However, thermal image cameras can give crystal clear video in pitch-black darkness from miles away.



A thermal image camera sees the infrared radiation emitted by an object, allowing it to detect minute changes in heat, without needing any ambient light. Everything emits thermal energy – even things that are very cold; in good or bad weather, day and night. A thermal camera can detect heat energy through smoke, dust, fog, and some sparse plants.

What is the difference between infrared and thermal?
Infrared cameras are sensitive to infrared (IR) radiation in the 250° C to 500° C range, while the range of thermal cameras is generally about -50° C to over 2,000° C. So, for an IR camera to be able to see something it must be over 250° C or it must be reflecting infrared radiation from something that is at least that hot. Night vision infrared devices image in the near-infrared, just beyond the visual spectrum, and can see emitted or reflected near-infrared in complete visual darkness.

Thermal image cameras are becoming a standard for the security industry when paired with traditional surveillance systems to give security professionals a more accurate picture of what is happening. Thermal image cameras can see things that the other cameras cannot – that the human eye cannot; things like a recently parked vehicle or an object having been moved. Their temperatures will be different or have changed which is easily detected with the TI camera.

The thermal image camera is used to detect the presence or absence of certain things – whether it is people coming into a restricted area, an object being left somewhere is shouldn’t, or something having been moved or removed from the scene that should be there. For example, in a security capacity, these type of cameras are not made to identify someone’s face and features but to notify someone that there is an intruder on the premises so they can act quickly and efficiently to apprehend the criminal.



You can’t hide your heat!

Other uses for thermal image cameras are quite varied and rather remarkable – from security, to firefighting, to medical and veterinary uses, to building maintenance, to harbor and boat safety and even as a driving aid in personal motor vehicles. With the use of a thermal camera a building inspector can actually see stress fractures that would have gone unnoticed with the human eye. Same with inspecting wiring – a wire may look like it was made correctly but under a thermal camera’s eye the wires may be rubbing together and getting ready to fail. Seeing the heat generated from the friction in both of these cases would eliminate costly and potentially hazardous problems.

Watch for the upcoming Thermal Image Sidewinder camera, the latest in the revolutionary P/T/Z Sidewinder line of cameras from WTI, which will be available soon. For more information on the Sidewinder series please visit http://www.gotowti.com/Products_Sidewinder.htm.

~The WTI Team



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WTI (Wireless Technology, Inc.)

Video Surveillance Products Dedicated to the Broadcast, Global Security and Transportation Markets!

www.gotowti.com ● www.wirelesstech.com

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Considering “Repeatability” of P/T/Z Cameras

Yes… another detail to consider when reviewing P/T/Z cameras; “Repeatability”. This may be of little concern when the intended P/T/Z camera application uses very low or no zoom within the presets of a tour. High end P/T/Z cameras with large optical zoom ranges tend to (and should) have higher repeatability ratings than other cameras. WHY?

First…
Repeatability, with regard to a P/T/Z camera specification, can be defined as the accuracy within which the camera position of the pan AND tilt axes are able to recall the previously set (aka: preset) position. Repeatability is typically given in degrees: 0.05°, 0.08°, 0.25°, etc.

Second…
The numbers given for repeatability are degree based. In effect, the repeatability specification references the ability of the camera to return to an exact position specified within the circular rotation of an axis. In the case of P/T/Z cameras… both the pan and tilt axes.

With these definitions in mind…
In a wide angle shot (with zoom at or near zero), any factor of repeatability found in today’s P/T/Z cameras is likely negligible. The image shift on either pan and/or tilt of even 0.25° when viewed after recalling a preset position will be very hard to notice.

The difference in repeatability becomes noticeable when a zoom setting has been associated with the preset position. A high zoom setting amplifies the image shift that occurs when the preset is recalled. The 0.25° image shift now becomes visible.

Repeatability can have a distinct impact on the resulting video image provided by the camera for real-time viewing as well as for what may be getting recorded into a DVR/NVR. The positioning of the viewable image provided by the recall of a preset should allow for variations due to the camera repeatability. This means that the user should test the presets several times to ensure the viewable image will still provide the desired video data even if the image has shifted.

Unrelated to the repeatability of the camera itself, yet related to the repeatability of image acquisition from a preset… stability of the camera mount location. The characteristics of the camera mount should be considered when establishing presets and expected image shifts. Mounting to the top of a pole is very common along highways, intersections, etc. Consider the suns effect on the pole material throughout the course of a day. One side of the pole is exposed to the sun during the morning hours while the other side is not; one side “hot” and one side “cold”. The material expansion coefficient, coupled with the height of the pole, can create an angular shift much greater than 0.05°. This angular shift may reverse throughout the course of the day as the sun changes position. Oh yes… and don’t forget wind!

In general, every P/T/Z camera has a number that specifies repeatability. A lower number will tend to indicate a higher quality of manufacturing, and is more likely to be associated with units incorporating a higher optical zoom or specialty video (thermal) capability.

~ David Scales, Chief Technology Officer


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WTI (Wireless Technology, Inc.)

Video Surveillance Products Dedicated to the Broadcast, Global Security and Transportation Markets!

http://www.gotowti.com/ ● http://www.wirelesstech.com/

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