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Ask the Expert: What should I take into account when deploying network cameras outdoors?

aterobertmoore.jpgIn today’s IP world, deploying indoor network cameras has become relatively straightforward. Sure, there are many different factors to consider, but new ease-of-installation designs have eliminated a lot of the legwork. Outdoor deployments, however, present different practical challenges. Weather, lighting, camera housing, connectivity and resolution all must be addressed. I’ve broken down the considerations into four sections to help ensure a smooth outdoor implementation.


February 25, 2010
By Bob Moore

Topics

Physical/Environmental
Don’t underestimate the effects of weather, especially in the north. Rain and snow can damage your camera and play tricks on your images, so an IP (Ingress Protection)-rated outdoor enclosure is extremely important.
Consider cold-weather-safe startups that allow cameras to function at -40°C and also power up to the proper temperature following a power failure. For PTZ cameras, if the internal mechanism and lubricant do not warm up properly following a power failure, you could damage or shorten the lifespan of the camera’s moving parts. Some manufacturers have intelligence built into their enclosures so that when the power comes up, cameras won’t operate until they reach a certain temperature.
Rain and snow aren’t the only liquid factors to consider. Determine if the housing will be exposed to water pressure (car wash), high-pressure cleaning (cruise ship), or severe dust. As mentioned above, check the unit’s IP-rating classification to verify the degree of protection against dust and water in electrical enclosures.
Don’t forget that environmental considerations go beyond weather. Certain installments may call for vandal-resistant housing (correctional facilities, school yards). Additionally, you’ll come across end users with specific mandates that affect your decision, such as windshield wipers installed on the enclosure to keep the viewing window clear.


Lighting

Day and night lighting present additional issues in outdoor implementations. Remember to mount the unit high and point it downwards to fight glare. Know the sun’s path and avoid any direct views into it. In fact, it’s best to minimize all sky views to avoid a wide range between darkness and bright sun. Finally, ensure that a fixed camera’s lens touches the enclosure glass, or else you’ll see a lot of reflection.
For bright lighting conditions, a camera with wide dynamic range will help to provide the best image for identification. Make sure your camera has an auto iris feature, which opens camera apertures in the dark and closes them in full light to protect sensors. 
For dark conditions, make sure to request a “true” day/night camera with an automatic I/R cut filter. Many cameras out there claim to be day/night, but the auto-sensor is crucial for best results.
If the end-user is concerned with perimeter detection, a thermal network camera may be an appropriate addition to your installation. Since these cameras utilize heat to detect objects, they are ideal for areas that can’t be fully illuminated or that are often affected by fog and smoke.

Connectivity and Power

It’s easier to connect and power up outdoor network cameras when they are attached to buildings, but when they are placed remotely outdoors you’ll need to consider additional factors. It may make sense to trench to provide power and network connections, but it can be expensive and unreasonable, particularly when network cameras are far away from the existing network.
Solar panels are a convenient and green choice if a local light pole is not present, but 900 MHz point-to-point connections are most commonly used. These connections provide better security than 802.11a/b/g/n, but you must avoid obstructions for a line-of-sight connection. If you have trees, hills or buildings between points, you’ll need a non-line-of-site wireless connection.
If wireless security concerns arise, explain that 802.1X security authentication for data connections prevents unauthorized individuals from making connections. By setting up a camera’s serial number, MAC address and model number with the layer 3 network switch, other units can’t gain access to the network because the network switch will block it.
Resolution
Depending on the specific outdoor applications — such as when you want to read licence plates from as far as 100 meters away — you need to determine the required resolution that will sufficiently handle the job. Also remember that a higher resolution camera might be less light sensitive.
Once you’ve established the areas to be monitored at the appropriate resolution, determine whether you need fixed, PTZ or a mix of network cameras. While PTZ network cameras provide scan and zoom features, they may only view 50 to 60 degrees at a time, leaving other areas uncovered. A combination of fixed network cameras for wider coverage, with a small number of PTZs for specific views, could be most cost effective.
There’s a lot to think about when installing a successful outdoor surveillance system, so I recommend creating a checklist before hitting the site so you cover all the bases.


Outdoor Checklist:
1. Physical/Environment:
  • Proper IP-rated outdoor enclosure
  • Cold weather-safe startup needed?
  • If PTZ camera, intelligent temperature control
  • Additional considerations (vandal resistant, end-user mandates, etc.)
2. Lighting
  • Mount camera high, aim lens down
  • Avoid direct sun views / minimize sky views
  • For fixed camera, lens must touch glass
  • Bright conditions: Wide dynamic range and auto-iris
  • Dark conditions: “True” day/night camera
3. Connectivity and Power
  • Is trenching reasonable?
  • For wireless, solar power or 900MHz point-to-point
  • Line-of-site / non-line-of-site
  • Wireless security
4. Resolution
  • Assess application needs
  • Assess areas to be monitored
  • PTZ, fixed or combination

 

 
 


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