Uri Guterman of Hanwha Techwin Europe champions the use of the DORI standard as the starting point for designing a video surveillance system.
The quality of the images which can be captured by many of the latest generation of super-high definition video surveillance cameras is simply breathtaking. Not only do they allow users to see ultra-sharp detail of objects and people within the field of view, the resolution capabilities of 4K and 8K cameras, for example, enables operators to digitally zoom in to see a non-pixelated image of just a very small part of a scene; this makes them an ideal solution for large open area applications where installing multiple cameras may be impractical or cost prohibitive.
The deployment of ultra-high resolution cameras, however, comes at a price in that they all capture large file size images which – when transmitted over the network – consume large amounts of bandwidth. In addition to this, they also have very large data storage requirements.
Some manufacturers such as Hanwha Techwin have developed proprietary compression technologies which when working in conjunction with H.265 compression are able to reduce bandwidth and storage demands by up to 80%. It is, however, still wise for system designers to question if it is really necessary to specify the highest resolution camera available whilst also bearing in mind the higher initial capital cost as well as ongoing network and storage requirements, even if they are reduced by complementary compression technology.
Let DORI help you specify the ideal camera
The phrase ‘horses for courses’ comes to mind when thinking about what system designers need to take into consideration when deciding on the best camera model for each location and objective. In this respect, the design of the system must obviously reflect the finding of the risk assessment and take into account an end user client’s operational requirements. For example, they may need to capture high quality, evidence grade images which will identify an individual or just wish to be able to verify an intruder alarm event.
Whilst many system integrators will be familiar with DORI, installers who are relatively new to the world of video surveillance may perhaps not know that the IEC EN62676-4 international standard provides time saving guidance as to which cameras should be specified. So, for those who are not familiar with the standard, here is a jargon busting overview of what the DORI acronym stands for:
- Detection: The quality of images captured by a camera allows a user to determine whether a person or vehicle is present.
- Observation: The captured images are able to provide characteristic details of an individual, such as their clothing.
- Recognition: The clarity of the images enables operators to see, with a high level of certainty, that an object or incident is the same as the one that an operator has seen before, e.g. a person, vehicle or a fire.
- Identification: The resolution and quality of the images enable an individual to be identified beyond reasonable doubt.
The ability of a camera to achieve these DORI defined objectives will depend on a number of factors such as the resolution, lighting and the amount of movement within the scene.
In terms of ‘Observation’, it is worth noting that sequential low resolution images can provide as much detail (albeit of a different nature) for the human brain to process, than high resolution still images, i.e. the movement of a vehicle is very different to that of someone walking.
However, as an example, a four megapixel in daylight conditions should deliver the following:
|Objective||2.88mm lens||3.6mm lens||6mm lens|
|Detection||43 metres||80 metres||120 metres|
|Observation||17 metres||32 metres||48 metres|
|Recognition||9 metres||16 metres||24 metres|
|Identification||4 metres||8 metres||12 metres|
However, the maximum distance that there can be between a camera and an object in order to meet one of the above requirements will vary depending on the lighting conditions, the compression format, camera locations and other factors.
The sensitivity of the camera sensors used by different camera manufacturers will also vary and in this respect Hanwha Techwin’s online Toolbox Plus enables system integrators to compare the specifications of its Wisenet cameras side-by-side and then compile a list of the products required for a specific project. There is also the added benefit of be able to generate a report on the estimated bandwidth and storage requirements for the project.
It seems almost too simple, but using DORI as a guide for designing a new video surveillance solution will ensure you do not waste money by over specifying the cameras needed for the job in hand. Equally important, the reverse also applies in that the DORI standard will help you avoid experiencing ‘buyer’s remorse’ as a result of installing cameras which are not in fact fit for purpose.
It is important, however, to bear in mind that DORI is a guide to ensuring you do not specify an unsuitable cameral; on its own, it is not going to choose the perfect camera for you. Other requirements need to be taken into consideration such as if the camera will need to have built-in IR illumination and/or have good WDR functionality because it will be pointing towards an outside window and will have to deal with variable lighting conditions.
As always, the best advice is therefore to work with manufacturers you believe you can trust and ask them to confirm that you have made the correct camera choice.
This article was originally published in the October edition of Security Journal UK. To read your FREE digital edition, click here.