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Vision in the crosshairs

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Greg Blackman looks at some of the uses for vision technology in military vehicles and for border defence

The military relies heavily on vision equipment to provide intelligence on enemy movements and for the safety of its soldiers on the ground. With allied troops still stationed in Afghanistan and Iraq, there is a constant need for greater sophistication in modern warfare equipment, including machine vision technology. Armoured vehicles, for instance, use video imaging for target acquisition and local situation awareness.

GigE Vision was developed as a video transmission standard for the machine vision industry, but is also suited for use by the military. ‘The standard is relatively mature and is at an acceptable level of development to be used in military applications,’ says Geoffrey MacGillivray, product manager at Pleora Technologies.

The core advantage of using Gigabit Ethernet to transmit video images is its potential for low latency when used in high quality, end-to-end implementations. ‘The pictures reaching the video monitor are virtually in sync with what’s happening in real life,’ notes MacGillivray. This is particularly important for driving applications, or in manoeuvring a vehicle by relying solely on the video information being supplied.

The goal for armoured vehicles is to reduce the exposure soldiers have to enemy attacks by securing them inside the vehicle. It is for this reason that many armoured vehicles have limited or no visibility and rely on video images to guide the driver.

‘The latency of those images must be fewer than 100 milliseconds or the driver could have difficulty controlling the vehicle and also the time difference between visual stimuli and physical feedback could lead to motion sickness,’ says MacGillivray. Unmanned vehicles, which are used heavily by the military for reconnaissance, have similar needs for low-latency images as navigation is entirely via onboard cameras.

Sebastien Dignard, European sales manager at Pleora Technologies, notes: ‘The transmission standard supports image processing data as well, and can relay information such as the range of potential targets from weapon sights, for instance.’

The ability to network multiple cameras into a system is a further advantage for military applications. Video sources can be pooled, giving an operator an overview of the scene. Multicast support, where video transmission is sent to multiple locations, is provided by GigE Vision. For instance, in an armoured vehicle the video signal often has to be supplied to the driver, the gunner and commander in the turret – and to the crew in the back.

The distance of cabling available using GigE, up to 100m, is a great advantage when it comes to providing video coverage over military vehicles. Alternatives, such as USB and FireWire, are more limited in cable length, 5-10m, and MacGillivray makes the point that it can be surprising how quickly cabling gets used up when installing cameras. With GigE Vision, cabling can cover a lot of ground and cameras can be positioned to provide maximum coverage.

The standard is reliable, which is vital for sending mission-critical information and, while GigE Vision in itself doesn’t guarantee data delivery, some products offer packet resend technology that guarantees full visual fidelity. Both compressed and uncompressed video is supported, which is key for military applications, where images are often sent to multiple locations for different purposes and with different receiving capabilities. In addition, it is a vision standard and therefore provides interoperability between new and existing video equipment.

GigE technology makes multi-channel streaming easier, which can be an advantage in military use. Image courtesy of Pleora.

‘GigE Vision has penetrated the military industry, but it is still largely at the development stage,’ comments MacGillivray. ‘It satisfies a lot of the key criteria required for military use and there are rugged versions that would be suitable for the hostile environments to which some military equipment is exposed. However, there is often a substantial period of time where equipment undergoes testing before it reaches a battlefield environment.’

Border control

Thermal imaging systems are classified into two distinct categories: those with uncooled detectors and those with cooled detectors. ‘Generally, cooled cameras are used in border defence applications as they provide a longer-range performance than versions with an uncooled detector,’ explains Christiaan Maras, marketing manager at Flir Systems.

Some models with a cooled detector are able to detect a man-sized target at a distance of 18-20km. These distances are sufficient for most border control installations, as the natural terrain often obscures the camera’s line of sight within 20km. Thermal imaging systems are often used in conjunction with visible cameras. ‘Installed on a pan/tilt, these multi-sensor systems can easily be integrated with radar systems in a so-called “slewto-cue” configuration,’ says Maras. If an object is spotted by radar, the thermal imaging camera will automatically turn in the right direction to provide images of the blip on the radar screen.

Multi-sensor configurations can also be equipped with GPS and a digital magnetic compass to ensure the operator knows where the thermal imager is – important for border security applications where the camera is installed on a vehicle – and in which direction it is pointing. Some systems also have a laser range finder to provide a measure of how far away an object is.

‘Based on subtle differences in temperature, called heat signatures, thermal imaging cameras create a crisp image,’ comments Maras. Thermal imaging needs no light whatsoever to produce a clear image and can operate in practically all weather conditions, and even the smallest of objects can be seen. ‘This makes them an excellent tool for numerous security and surveillance applications, including border security,’ he says.

Thermal imaging also works during the daytime. It cannot be blinded by the sun like a normal CCTV camera. Furthermore, thermal contrast is extremely difficult to mask, so people trying to camouflage themselves by hiding in bushes or shadows will be detected.

Flir has provided thermal imaging systems for various border control programmes worldwide, in Europe, Asia and in the Americas. Major border programmes are running in the Middle East, in countries that border the Schengen area, as well as in other European countries that want to protect their borders, against illegal immigration, for instance. Both land and coastal surveillance programmes exist.

Thermal imaging equipment used for other application areas is also finding its way into border defence. Maras cites one example: ‘The same thermal imaging cameras that are currently being installed in selected BMW models can easily be used by border control vehicles to provide so called “see without being seen” patrol units, where vehicles carry out border control checks without headlights or spotlights.’

Border patrol units can also be equipped with handheld thermal imaging cameras. In an open call for tenders by the European Commission for border control equipment, German company Jenoptik developed its VarioView 150 binocular thermal imaging system, which is to be used in the Ukrainian government’s BOMUK project (Border management improvement: equipment supply to the State Border Guard Service of Ukraine).

Jenoptik’s VarioView 150 binocular thermal imaging system was developed in response to an open call for tenders by the European Commission for border control equipment. Image courtesy and copyright of Jenoptik Laser, Optik, Systeme, Jena, Germany.

The European community is specifically promoting improvement in the defence of Europe’s external borders, and the BOMUK project aims to increase equipment supplies to Ukraine’s Border Guard Service with thermal imaging satisfying just one aspect of the project.

The thermal imaging binoculars are based on an uncooled infrared detector with a resolution of 640 x 480 pixels. To meet the specifications of the European Commission tender, they were designed to be light, weighing less than 3kg, with a long battery life, up to six hours, and have the ability to detect persons at a distance of up to 5km (7km for vehicles). Heiko Richter, international sales manager – infrared camera technology at Jenoptik’s Defence and Civil Systems Division, says: ‘These kinds of distances are traditionally covered by cooled cameras and are usually outside the imaging range of uncooled systems.’ The average uncooled camera has a detection range of approximately 2km for a man-sized object.

Jenoptik specialises in producing thermal imaging equipment for various areas, including defence, but, traditionally, has worked in industrial areas. A combination of different divisions at Jenoptik was involved in designing the camera to meet the specifications of the tender.

‘Cooled cameras are often used for border defence applications due to their long imaging range,’ explains Richter. ‘Uncooled imagers have the advantage of being lower weight and having lower battery consumption than cooled versions, and so are preferred as a more portable alternative to cooled cameras.’ The VarioView provides a particularly long imaging range for an uncooled detector and also contains a laser range finder, which calculates the distance to sighted objects.

The VarioView underwent testing earlier in the year and the first batch of three will be delivered to the Ukrainian State Border Guard Service in October 2008.

Richter believes: ‘As European borders become more open, border control officials will still be required to patrol borders and will still have a need for thermal imaging equipment. Uncooled equipment will begin to replace cooled cameras in the future, as the technology requires little maintenance, is simple to use and is convenient for officials patrolling a border.’

Maras comments: ‘Thermal imaging is an important element in many border security programmes and, when integrated into a system with other sensors, such as radar, provides an effective approach to border control.’

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