Panoramic Surveillance

One innovation that has come to the fore in recent times in the field of video surveillance is the panoramic camera. With the ability to provide a real-time all-round or ultra-wide angle view of a protected area, these cameras can enhance the overall level of protection delivered by a security solution. With most major manufacturers now offering such devices, it is strange that some installers and integrators have not embraced what is on offer. Benchmark considers the role of panoramic cameras to assess what they deliver.

The increased popularity of panoramic video is due to the fact that the various technologies used to generate such video streams all have one thing is common: the supplied video enhances security for the customer, whilst also delivering a wide range of added-value benefits. There is an overwhelming business case for the technologies, and as a result demand is increasing in certain applications.

As anyone who has been in the security industry for some time will know, panoramic devices are not new. They have been available for nearly 20 years. Admittedly, during the early stages of development the products had significant limitations with regard to performance.

The first commercially available panoramic camera raised a significant amount of interest in the video surveillance industry. The camera was a solid-state 360 degree virtual telemetry dome. At the time its biggest challenge was ensuring that installers and integrators understood what the camera could offer.

It was a watershed in surveillance, and arguably was the first camera that offered true situational awareness. However, it is only fair to say that despite its potential it was never going to be a commercial success. The unit featured a one megapixel camera – at that time a staggeringly high resolution – fitted with a fisheye lens. It required a dedicated server for each camera head, and because computer processing capabilities were – at that time – low performance with a high cost, video streaming and overall image quality was obviously compromised.

The camera was only capable of delivering a monochrome image. In normal operating mode it recorded one frame per second, but during alarm events this could be increased to 12 frames per second. The 360 degree scene was split into four quad displays which were viewed at VGA resolution.

Even using the default minimal frame rates, the maximum recording time for each device was 48 hours. However, probably the biggest barrier to commercial success in security applications was the cost.

In 1999, when the team at Benchmark was given the first preview, the basic price of the device was equivalent to that of more than 30 high-end cameras, plus a couple of high-end DVRs and monitors.

Despite these negatives, the camera still created a buzz throughout the industry, because it gave a glimpse of what was possible using a digital platform. Since then there have been many variations on panoramic cameras, and in the past few years most credible manufacturers have launched such a device.

A panoramic view

There are several ways in which panoramic cameras operate. The differences will inevitably impact on which applications the devices are best suited for. Panoramic cameras can deliver all-round 360 degree views or wide angle 180 degree views. Some manufacturers will describe the latter options as hemispheric cameras, but for the purpose of this assessment we will include them as panoramic devices. Less common are 270 degree cameras; these are designed to be mounted on an external corner of a building.

There are two main approaches when creating a panoramic video stream. The first method makes use of a single camera fitted with a fisheye lens. This method can also be achieved by using an after-market lens.

The second approach involves the use of multiple camera sensors, typically four with each capturing a 90 degree view for a full 360 degree view. Other configurations are available.
In both cases, once the footage is captured it undergoes processing to deliver a variety of different displays, again dependent upon the applications’ needs.

While both approaches deliver panoramic views, there is a slight difference in how this is achieved.

With single sensor cameras utilising a fisheye lens, the camera captures a full image of the entire 360 degree area. In its raw format, the video is pretty much unusable. However, by using a dewarping algorithm, software is able to manage elements of perspective in the video, thereby presenting a visually correct image. Cameras are either supplied with dedicated dewarping software, or will use on of the established algorithms. The vast majority of VMS solutions now also support dewarping for many of the leading devices.

These cameras will allow the video to be viewed in a number of formats. Typically these include 360 and 180 degree panoramic views, as well as regions of interest which can be viewed in various formats including 4:3 and 16:9 aspect ratios. Because the cameras stream the entire 360 degree image to the recording server, this means that all details in the viewed scene are recorded. Therefore, an operator has the ability to view any part of the protected area when reviewing the recordings. This allows them to rerun the video and view different areas, depending upon their needs.

Some of the lower end 360 degree cameras perform dewarping at the camera. This, however, defeats the purpose of these devices, as the recording server will only capture the dewarped streams. If an operator needs to change the field of view when assessing recorded video, they will be unable to do so unless the full 360 degree image has been archived.

It is worth noting that when considering the resolution of single sensor fisheye cameras, the quoted figures are for the entire image. Therefore, if a camera is specified as delivering 5 megapixel video, that resolution will be for the full panoramic image.

It must be remembered that the captured image will not fill the full chip surface, as a fisheye lens delivers an elliptical picture. To ensure the full image can be accessed, the corners of the chip will not capture usable video. Therefore, if a 90 degree view is displayed, the image will have less than 25 per cent of that resolution. If there is any digital zooming, the resolution will subsequently decrease.

It is also important to realise that display resolutions may allow for upscaled images. This approach is used to ensure that displays are native for monitors and is not an indication of video quality.

Another approach to single sensor devices delivering panoramic surveillance is to use a specially designed lens with accompanying software to deliver a similar result. A growing number of manufacturers support this functionality through their cameras. This can have a benefit where existing devices are compatible with the system, thereby allowing the introduction of 360 degree video without the need to purchase a complete camera. With a panomorph lens added, some units can be converted to deliver panoramic coverage.

The second approach is to deploy multi-sensor cameras. These units include a number of individual cameras. The individual cameras capture traditionally formatted video, so there is no need for dewarping. These devices operate as a single camera, so there is a single network connection and a single power connection (unless PoE is used).

With regard to video display, either the multiple camera outputs can be viewed alone, as a quad display, or can be ‘stitched’ together to create a panoramic view. With the latter option, it is then possible to electronically pan, tilt and zoom within the panoramic image without any need to change views.

With multiple sensor cameras, you can be a bit more assured about the image quality. For example, four HD1080p cameras mean that in a panoramic view or as regions of interest, the image quality will be HD1080p. Obviously this will reduce with digital zoom, but only in the same way that it will for a standard HD1080p camera.

While both forms of panoramic cameras have many similarities, there are also differences that can impact on suitability for certain applications.

Realistic expectations

The benefits of panoramic cameras are obvious, and the units undoubtedly can enhance the overall security of many applications. When installed correctly, and when considered with realistic expectations, these devices represent exceptional value for money. Despite this, and the fact that many installers and integrators have great success when specifying panoramic cameras, there does remain a degree of negativity from some in the industry towards these units.

Often, unrealistic expectations for what can be achieved comes from mixed marketing messages about the devices. This can lead to confusion over the expected levels of image quality and suitability for certain tasks.

In a recent discussion about the use of panoramic cameras, one message from several installers and integrators was that they would not use these devices as those they had tried failed to live up to their billing. Many of those voicing concerns pointed out that some manufacturers promote the cameras as being able to replace numerous static devices. This is a message which is common amongst those offering the cameras, but in the vast majority of cases is not an accurate one.

A distinction has to be made here between single sensor and multiple sensor devices, as the situation changes slightly when viewing the different options.

Whilst there are some high resolution exceptions to the rule, many panoramic cameras – especially single sensor models – are designed to provide an overall view of the scene. They are designed to be used for general surveillance in addition to other static or PTZ cameras, rather than as a single replacement for all other devices.

As already mentioned, it should be remembered that in a dewarped scene, the viewed area will represent a small percentage of the total image and subsequently of the total resolution. Add digital zoom and the quality can quickly deteriorate.

Interestingly, a number of credible manufacturers who specialise in panoramic devices (and have many years of experience in this field) often advise that single sensor panoramic cameras only be used to provide an overview. The video allows general activity to be tracked and continuity to be proven, but may not always deliver images suitable for evidential purposes.

Resolutions are increasing for single sensor devices, and as a result some installers and integrators who have previously been disappointed by image quality may find that many of the issues have been addressed. However, it still remains the case that in many applications the cameras won’t be suitable to replace multiple dedicated devices.

A slightly different approach has been taken with multi-sensor cameras. Often these can replace multiple devices, but not all devices in a protected area. However, they can be deployed using motion detection of video analytics which, when activity is detected, will send a linked PTZ camera to a pre-set position covering the triggered detection zone. As this approach allows the use of optical zoom on a fully functioned camera, image quality is preserved, even over long distances.

The combination of a panoramic camera coupled with a fully functioned dome delivers both evidential quality video for identification and general wide-area surveillance to provide evidence of continuity.

Other considerations

It is worth noting that when panoramic cameras are deployed, the amount of background processing to both manage the video stream and either dewarp regions of interest or stitch scenes together will be significant.

It is true that modern cameras possess more processing power than previous generation devices, but there is also a greater demand for cleaner video, smart triggering and a host of other functions.

Because of their mounting alignment, a number of manufacturers are equipping ceiling-mount panoramic devices with business intelligence functionality such as people counting, heat-mapping, flow management, etc..

Additionally, panoramic cameras face the same challenges with regard to any ultra-high resolution devices. Issues with pixel density that can affect low light performance.

Bandwidth management also needs to be considered, as panoramic streams contain a significantly higher amount of information than a traditional static camera view. Because one of the major benefits of panoramic devices is the ability to virtually pan, tilt and zoom through both live and recorded footage, it is imperative that archived video retains its original quality. After all, there may be elements of the video required for evidential purposes which may only be identified as essential after an event.

In order to realise the true potential of these devices, installers and integrators must remember that the power of panoramic cameras lies in their ability to review events and investigate every part of the protected area. The elimination of blind spots, coupled with the ability to alter the camera view in recordings, is the true strength of this technology. Any attempt to reduce camera numbers or cut costs by implementing panoramic cameras to reduce hardware costs will result in disappointment.

In summary

It would be fair to say that panoramic cameras are not alone in having their true benefits misrepresented in the past. There seems to have been something of a trend in some sectors to justify sales with a claim of cost-cutting in the form of allowing multiple static cameras to be replaced with a single unit. This is still seen today.

Cost-cutting and reducing hardware requirements were never valid reasons for specifying such devices. These were only raised as a marketing point when the devices started to be pushed for use in mainstream applications where the benefits most likely would not be fully realised.

The reality is that good quality panoramic cameras are unlikely to reduce the cost of an installation. If anything, they will usually increase the cost. That said, they still represent good value for money, because the benefits they introduce can enhance site security to a very significant degree.

There is no doubt that when used correctly, and in the right application, panoramic cameras are beneficial, credible and worthy of consideration. They enhance existing systems and add to what is delivered by more traditional static and PTZ cameras.

Specification of panoramic devices is subject to the usual provisos: ensure the manufacturer has an established track record in video surveillance, ascertain whether the system has any proprietary elements that may restrict use in future system expansions or upgrades, and ensure that the performance – when used in the real world – meets the expectations of all stakeholders.

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