Drones and surveillance: an opportunity for AV?

Continuing our series of Q&As supporting InAVate's focus on drones in the Jan/Feb 2015 edition, Tim Kridel talks to Andrea Sorri, Axis Communications business development director for government, city surveillance and critical infrastructure.

TK: What are some existing and potential pro AV applications of drones? For example, I suppose rental/staging companies could use them for getting video during events that’s the then fed to videowalls and other displays around a venue. Or AV integrators that specialize in security might use them for applications where it’s not practical or possible to permanently install a camera or use a cart-mounted one.

AS: Video-equipped UVAs can be quite helpful in scenarios where it's not practical or possible to permanently install a camera. Such an implementation provides visibility for areas that a fixed camera cannot provide, and also offers a unique perspective on a scene, such as a concert or sporting event. One use model would be in the case of civil protection for search and rescue during disasters – avalanches, floods, landslides, plane crashes, etc. In extreme environments or rural areas this type of aerial visibility can be efficient in evaluating conditions or locating people. UAVs could also serve useful purposes in more populated areas for general surveillance and security, but the legal and privacy issues involved with such use still need to be worked out.

TK: One difference between drones and other types of surveillance installations is that the drone is always moving around. Wouldn’t that mean more variables – such as light and distance – that will affect video quality? If so, what would AV integrators need to consider to ensure that drones provide consistently good-quality images? For example, selecting the right camera seems to be one obvious consideration because in your stratocaching video, the images appeared to be consistently good.

AS: Image quality is a critical feature of any camera but it is important to first understand what the intended use of the image being captured is meant to be. At Axis we talk about image usability. This means we try to optimize the image so the user gets the most amount of detail from it. An image can be visually pleasing but if the user can't see the details needed to accurately observe a sequence of events or identify a person or other details, it's not useful from a surveillance perspective.

Since a drone is a moving object, it presents different challenges than a stationary installation. For example, the level of light will often change quickly from low light to very strong light, and back. This is similar to other moving applications such as buses. A bus will quickly make a sharp turn or enter a tunnel, and that will change the light conditions. Cameras need to be equipped with up-to-date sensors and algorithms to address these light changes.

Another lighting challenge is different light levels within a various parts of a scene. This is called a dynamic scene. Axis offers cameras that can use multiple exposures for each individual frame in the video. These cameras will take one exposure with a short exposure time and another one with a longer exposure time and merge them into one frame in the video. The result is better quality and visibility of details in both the dark as well as the bright part of the scene.

Local contrast is another important aspect of image usability. This involves automatically verifying the individual pixels in the image and comparing them to neighbouring pixels to make sure the contrast between them are optimally presented.

When choosing a camera for a drone, an important consideration is the form factor that can be supported. Drones can range from being very small to being helicopter-sized objects. In an object with the size of an helicopter, almost any camera could be used. There could even be a possibility to use a PTZ camera that would allow the user to optically zoom in on specific details. In smaller objects, the form factor for the camera must be small and light.

For example, the AXIS F Series is based on a divided concept where the sensor unit with the lens and sensor is separated from the rest of the electronics in the main unit. This allows the use of miniature sensor units that can be mounted in very small spaces on a drone while putting the main unit away where there is space for it.

Another requirement to be considered is the environmental conditions of the intended use. A rugged camera model may be required for extreme environments.

Since drones will often be operating at long distance from the scene, high-definition video is an important consideration. A high-resolution video allows the user to digitally zoom in on an object without losing much of the details. Multi-megapixel camera offers high resolution and wide angle which is required for above overview. Multi-megapixel lenses have less depth of field which is an aspect to take into consideration based on the flying altitude of the drone.

TK: I’m trying to get a sense of the types of companies – Drone vendors? Drone systems integrators? Something else? – that businesses and other organisations typically turn to when they decide that they have applications that could benefit from drones. InAVate readers have a lot of experience designing, building and maintaining systems that capture and manage video, such as for surveillance. But I’m not sure if the organisations that hire them for those types of applications would consider them a natural place to look when it comes to drone-based video applications. What does the drones ecosystem look like in terms of the types of companies available to help organisations implement any type of drones application?

AS: While the market for drone-based cameras may not yet be big enough for specialized integrators, companies with experience in other types of moving or mobile installations could be qualified to perform installation on drones. Businesses looking for that type of experience should look for systems integrators who have worked with transit systems, for example.

One possible scenario related to drones it is not only to use them as mobile flying eye but something to manage and control from the ground. Network video cameras installed in cites and critical infrastructure could be a system also to help to control them, to monitor where they are, what they are doing, because there will be good drones and bad drones.

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