Thermal imaging: value for money?

Previously, Benchmark has looked at the arguments for and against investing in thermal imaging as a security tool, and asked whether the true value of the technology as a security tool justifies the cost. In this assessment Benchmark looks at how thermography stacks up in the field as a critical element of a perimeter security system.

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n previous looks at thermography Benchmark delved into the theoretical side of thermal imaging used as a security tool. The debate over the value of thermal imaging has been going on for many years. While a few installers and integrator appreciate the value of the technology, it has also not been on the agenda for a large number of sites for one reason: thermal imaging was price-prohibitive.

In recent years, that has changed significantly. Today some thermal imagers are available for the same cost as a good quality video camera, and we’re even seeing the first devices in the security market that are the same cost as budget video cameras.

With affordable thermal imaging available today, installers and integrators owe it to themselves – and their customers – to at least investigate the value of thermal imaging in security applications.

The cameras used for this assessment came in variety of configurations, and this illustrates the reality of cost-effective thermography designed for security applications. In theory, thermal imaging technology can be used for a wide range of smart applications. However, in order to keep budgets to a realistic level, many of the theoretical benefits don’t often translate into real-world installations.

The assessment was carried out in a site with a long and open perimeter. It was carried out in late Spring and the weather was typically British, with day temperature highs of 12 degrees C and night time temperature lows of 6 degrees C. It was predominantly cloudy with periods of rain and drizzle.


EQUIPMENT PROFILE
VCA ITS650LD-A36

Resolution: 206 x 156
Lens: 4mm F1.2
Compression: H.264/M-JPEG
Output: 800×600 (max) / 1280×720 (max)
Frame Rate: 9fps
Streaming: Dual
Audio: Two-way
Storage: MicroSD
I/Os: 1 in, 2 out
ONVIF: Profile S and G
Power: PoE/12V DC
Analytics: Direction, Dwell, Enter, Exit, Tamper
Range (Detection): 333 Metres
Range (Recognition): 83 Metres
Range (Identification): 48 Metres

The ITS650LD-A36 is a compact and lightweight thermal imaging device from VCA, which utilises a 12µm uncooled vanadium oxide microbolometer. The imager incorporates the company’s video analytics. A number of rules are included as standard, while the full range requires an additional licence. The camera is billed as a cost-effective entry-level thermal imager.

Installation Notes: The ITS650LD-A36 should be supplied with a utilities CD which includes a software element for addressing the units. Ours did not include this, and so set-up is via a static IP address which is calculated using the MAC address. The menus are simple and straightforward, which is a bonus as the imager is supplied with a quick start guide but no manual, nor is there any reference of the product on the VCA website. The imager specifications include an embedded microSD card for storage, but on our unit this did not function!

Performance Notes: While the still images on the left indicate the type of detail that the thermal image from this unit delivers, motion does make the identification of targets easier. However, it was felt that only at distances of around 30 metres or less was it obvious that a target was human. At 80 metres, there was no certainty of what it might be.

Whilst the viewed image didn’t give enough detail to make certain accurate decisions based upon an incident, the motion detection functionality could be configured to detect any intrusion across the perimeter, and this function was consistent and reliable.


EQUIPMENT PROFILE
TBT TPV-ISW-BDT-PD/19

Resolution: 320 x 240
Lens: 19mm
Compression: H.264/M-JPEG
Output: D1 Thermal / D1 Video
Frame Rate: 25fps
Streaming: Dual
Audio: No
Storage: MicroSD
I/Os: 1 in, 1 out
ONVIF: Supported
Power: PoE/12V DC
Analytics: Basic motion detection
Range (Detection): 845 Metres (People) / 2055 Metres (Vehicles)
Range (Recognition): 160 Metres (People) / 415 (Vehicles)
Range (Identification): 120 Metres (People) / 320 Metres (Vehicles)

The TPV-ISW-BDT-PD/19 is a bullet-type dual video and thermal imaging device from TBT. It combines a 17µm uncooled vanadium oxide microbolometer with a 960H video camera. It will only stream from one of the units via the LAN; to view both inputs requires the use of a secondary coax output.

Installation Notes: The TPV-ISW-BDT-PD/19 is supplied with a utilities CD which includes a software element for addressing the units. Ours worked as expected. Once configured you need to log in. The default user and password details are not included in the manual so you will have to guess this. You are then prompted to download the latest Java environment. Due to a number of recent vulnerabilities, many users don’t trust Java. Indeed, Java itself is thin on trust, so when downloaded it won’t let the camera stream load as its certificate is not valid! It needs to be added to an exception list to function. The camera features a miniaturised keypad: a throwback to its analogue past. Configurations via the LAN simply present a miniaturised screen from the keypad-based display, and the process is painful.

Performance Notes: The still images on the right indicate the type of detail that the thermal image from this unit delivers. As with the other units, it should be noted that motion does make the identification of targets easier. It was felt that identification that the target was a person was possible at distances of up to 120 metres. This additional range was made possible because the unit was fitted with a 19mm lens, compared with the VCA imager’s 4mm option. In general, this had more impact than the slightly increased resolution.

While visual detection was generally acceptable, the integral motion detection doesn’t have a great degree of configurability and was felt to be too basic for the demands of long range perimeter protection.


EQUIPMENT PROFILE
Axis Communications AXIS Q1941-E

Resolution: 384 x 288
Lens: 19mm
Compression: H.264/M-JPEG
Output: 768 x 576
Frame Rate: 25fps
Streaming: Triple
Audio: Two-way
Storage: MicroSD
I/Os: 2 in, 2 out
ONVIF: Profile S
Power: PoE/12V DC / 24V AC
Analytics: Basic motion detection, third party IVA
Range (Detection): 580 Metres
Range (Recognition): 140 Metres
Range (Identification): 70 Metres

The AXIS Q1941-E is an external thermal imager. It is available with a range of lenses; our unit was a 19mm model. It utilises a 17µm uncooled vanadium oxide microbolometer. The thermal imager is equipped with motion detection, but also supports third party analytics via the Axis ACAP programme. The thermal imager incorporates Zipstream technology to manage bit-rate requirements, and includes a full range of options for further stream management.

Installation Notes: The AXIS Q1941-E is supplied with a utilities CD which includes a software program for addressing the units. Axis Communications has one of the most consistently dependable utilities, and once more it worked as expected. Once configured the next task is to set a password for the root user. Initial set-up screens are shown using M-JPEG compression; if you want to use H.264 an additional plug-in will be loaded. The process is automatic. The menus are well designed, and through the use of tabs it is simple to navigate quickly to the required elements. Set-up is very simple, and any installers or integrators who are familiar with the Axis interface will feel immediately at home.

Performance Notes: The still images on the right indicate the type of detail that the thermal image from this unit delivers. Of all the devices included in the assessment, the streams from the AXIS Q1941 have the highest degree of detail. It does have a slightly higher resolution than some of the other imagers, but the differentiation in the images makes spotting intruders a lot simpler. With motion it is very obvious what you’re looking at, even out to distances of close to 200 metres.

While visual detection was the best in the assessment, the use of motion detection is good but not great. If you’re looking for more advanced video analysis, then an add-on application from an ACAP partner is recommended.


EQUIPMENT PROFILE
Mobotix MX-M15-TR079

Resolution: 336 x 252
Lens: 7.9mm
Compression: MxPEG / M-JPEG
Output: 2048 x 1536
Frame Rate: 9fps
Streaming: Single
Audio: Two-way
Storage: MicroSD
I/Os: Optional accessory required
ONVIF: Not supported
Power: PoE
Analytics: Basic motion detection, MxActivitySensor
Range: Not stated

The MX-M15-TR079 is an external thermal imager based upon the Mobotix decentralised platform. The housing is capable of supporting two camera modules, so the thermal image can be supplemented with a video stream. Our unit did not include a second module. The imager is available with a range of lenses; our unit was a 7.9mm model. It utilises an uncooled vanadium oxide microbolometer. The unit is equipped with motion detection and MxActivitySensor. The thermal imager incorporates integral archiving and a built-in motion detector.

Installation Notes: Mobotix supplies its own video management system, which will support third party devices, but the focus is on a Mobotix-centric system. The manual is a bit of a slog, but once you’ve read the necessary elements things are straightforward. Powering up the unit while depressing a reset switch sees the unit start in DHCP mode, and once booted up the speaker announces the IP address. This method does require switching server configs, but the static IP address was not as specified on our unit. Once connected the set-up screens are straightforward and configuring the thermal imager is fairly easy.

Performance Notes: The still images on the right indicate the type of detail that the thermal image from this unit delivers. There was a good degree of detail in images at a closer range, but this dropped as the range increased. Whilst it does have a higher resolution than some of the other imagers, it also has a fairly short lens focal length. With motion it is obvious what you’re looking at out to distances of close to 100 metres.

While visual detection was okay, the use of MxActivitySensor is good. However, be aware that performance may be impacted by longer ranges.


Defining identification

In security terms, when we talk about identification we are looking at the ability to positively identify an individual. To achieve this there is a requirement for highly detailed images that can deliver a video image which proves the identity of an individual, or person-specific data with a full audit trail that can establish their presence in a given place at a given time, without doubt.

In thermal imaging, the definition of ‘identification’ is based upon the Johnson Criteria, a performance index created nearly 70 years ago to judge the accuracy of night vision goggles. These consider identification as there being something of interest there, which is acceptable in a theatre of combat.

Modern implementations of the Johnson Criteria claim that 12 pixels of information are required for identification. Despite this being wholly at odds with the definition understood by the security market, security manufacturers still use it as a specification for their products.

During the assessment, ascertaining what was a person and what was another source of radiation caused some debate. However, at no point did any of the Benchmark team feel that quoted figures for range were realistic in a security application.

Because of the image detail included in a thermal image, it is not possible to achieve identification of an individual. However, in order to have some certainty that a target is a human, we felt that as a rule of thumb usable ranges could be as little as 20 per cent of the claimed figure. Whilst the specified ranges are correct under the Johnson Criteria, security has different needs.

Lens considerations

Thermal imagers and video cameras both require lenses, but that’s where the similarities stop. For those familiar with video lenses, the optics for thermal imagers present a different proposition. However, the good news is that installers and integrators, they are unlikely to have to do move than specify a focal length.

While video lenses are made from ground glass, thermal imaging lenses are not, as thermography is obstructed by glass. Instead the units use lenses from of a variety of materials, the most common being Germanium. Lenses are fixed focal length and are usually factory configured, so they don’t require focusing.

Thermal imager lenses have a variety of focal lengths, and the performance is similar to video lenses. Short focal lengths offer wide angles of view with less magnification, and longer focal lengths have a narrower field of view with more magnification.

Thermal positives

Thermal imagers really come into their own in challenging conditions. In periods of twilight or darkness, fog or inclement weather, thermography can deliver consistent images which identify the presence of intruders. When motion is present, it does become much easier to determine whether a target is human or an animal.

Thermal imagers also work well with intelligent video analytics. Because these tools work on the visual information in a stream, they are more successful with the almost default white hot palettes.
Small differences in resolution do make a difference, as is evident from our assessment, but with realistic expectations most thermal devices can be used to add value to a security solution. The real question is whether the devices are worth the investment.

Value for money?

In the past it was hard to Justify the use of thermal imaging on many sites. Today things have changed, and whilst the new breed of low cost imagers are very price competitive, the available performance is lower than many expect.

The performance often comes down to resolution and lens. Skimp on either and the range of the unit is reduced. There are imagers that cost the same as budget cameras, but their usefulness – and subsequently their value for money – is limited. They will be fine in a few applications, but not for all.

If you’re looking for thermal imagers that will deliver detail and detection over ranges of 100 to 200 metres, then the cost will likely be around the same for a very high end security camera.

Given the abilities of such devices, the cost can be justified and the thermal imagers do represent good value for money for mainstream applications.

For most, this middle ground is where thermal imaging makes sense. High end imagers are the domain of high risk sites with deep pockets and the low end units lack the quality needed for credible security.

BENCHMARK
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