Uri Guterman, Head of Product & Marketing for Hanwha Techwin Europe, champions the use of the DORI standard, as the starting point for designing a video surveillance system and how in doing so, one can ensure that the specified cameras are able to cost-effectively meet the end-user’s expectations.
The quality of the images that can be captured by many of the latest generations of super-high definition video surveillance cameras are simply breathtaking, allowing users to see ultra-sharp detail of objects and people within the field of view.
4K and 8K high-resolution cameras
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, making 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. They also have large data storage requirements.
Proprietary compression technologies
Some camera manufacturers, such as Hanwha Techwin, have developed proprietary compression technologies
Some camera 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, 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.
DORI helps 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. They may, for example, need to capture high-quality, evidence-grade images, which will identify an individual or able to verify an intruder alarm event.
DORI - Detection, Observation, Recognition and Identification
While many system integrators will be familiar with DORI, installers who are relatively new to the world of video surveillance, perhaps do 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, listed below is an 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. it is a person, vehicle or a fire.
- Identification: The resolution and quality of the images enable an individual to be identified beyond a reasonable doubt.
Cameras ability to achieve DORI defined objectives
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.
As an example, a 4-megapixel camera in daylight conditions should deliver the following:
|Objective||2.88mm lens||3.6mm lens||120 metres|
|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.
Sensitivity of the camera sensors
The sensitivity of the camera sensors used by different camera manufacturers will also vary
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 compile a list of the products required for a specific project. There is also the added benefit of being 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 no wastage of 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 to avoid experiencing ‘buyers’ remorse’, as a result of installing cameras that are not fit for purpose.
Other key factors, such as IR illumination and WDR functionality
It is important, however, to bear in mind that DORI is a guide to ensuring that an unsuitable camera is not specified, but on its own is not going to choose the perfect camera for a job.
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.