Surveying for CCTV
This and the next two chapters can be interpreted from two points of view. First, the installing company when designing a system. Second, with regard to the potential customer what to expect from a well-presented proposal.
So far this book has defined all the elements of a CCTV system and provided guidelines on their operation and limitations. So now comes the time to visit a site and design a system. This chapter cannot give detailed instruction on how to do this, just as a book on mechanical engineering cannot show a person how to design a bridge. However, it does illustrate a structured approach to producing a system design that will ensure a satisfied customer. This chapter is intended for those situations where a company is invited to make a system proposal from scratch. The writing of specifications is covered in Chapter 21.
Obtaining the Brief
The initial meeting with the prospective customer is the most important link in the chain to providing a final acceptable solution. It is essential at this stage to find out exactly what the user is expecting to achieve. It is also useful at this preliminary meeting to explain the relationship between general surveillance and identification, which is that clear identification is a trade off against the width of the area in the scene. To start, try to obtain a definition of the fundamental objective of the system. This could be along the lines of the following examples.
- To obtain clear identification of every person passing down the corridor to the wages office.
- To view the general car parking areas and alert security guards if there are persons acting suspiciously.
- To identify the numberplate of every vehicle passing the inward barrier.
- To cover the entire perimeter of the site and be alerted automatically in the event of an intruder.
- To act as confirmation of an alarm created by an intruder detection system.
- To provide general views of the site and identification of all persons at front and rear entrances.
Having established the prime need of the system, use something like the following checklist to establish the basic requirements and environment. The checklists given in this chapter are intended as a guide only. Each company should create their own according to the general nature of its business.
|Only a simple deterrent.|
|A general view of what is happening in specific areas.|
|A detailed view of what is happening in specific areas.|
|Daytime only use.|
|Nighttime only use.|
|Day and night use.|
|The system is for use indoors only.|
|The system is for outdoor use only.|
|The system is for both indoor and outdoor use.|
|Is the system to be colour, monochrome, or a mixture?|
|To be integrated with other systems?|
|Will full control of the system be on the site?|
|Is remote monitoring required, i.e. central station?|
|Is continuous recording of all areas necessary?|
|Automatic activation of aspects of the system is required in the event of an alarm.
(VCR switched to real time, a camera sent to pre-set positions, etc.)
|Adequate lighting is available.|
|Supplementary lighting is to be provided.|
|Mounting locations are available for all cameras.|
|Mounting locations are not available for all cameras.|
|Will the system be monitored continuously?|
Table 20.1 Checklist for System Brief
The list can be extended considerably but the intention is to obtain a general impression of the brief. It is not needed to answer specific questions at this stage.
The next phase is to have an informal walk around the site with the customer to become familiarised with the topography. This also enables the names of locations and areas to be learned. The site in this meaning could be a whole estate, a warehouse or a retail store, etc. This initial walk around the site will be invaluable in leading up to the more detailed survey to be carried out.
Surveying the Site
Most customers will provide a drawing of the site. If not, then a second walkabout will be necessary to make a drawing with key dimensions on it. The main areas of interest will now be known, therefore the amount of detail drawn can reflect this.
This article is an extract from chapter 20 of 'The Principles & Practice of CCTV' which is recognised as the benchmark for CCTV installation in the UK.