Time-of-flight sensing has been around for a good few years, and offers a number of benefits over video information in a number of applications. Whilst the devices are referred to as ‘cameras’, the results are a world away from surveillance, but in high-risk access control applications their implementation makes a lot of sense.
Time of flight cameras have been around for a number of years, and have started to appear in applications in the private sector for the past 10 to 15 years. The cameras use laser technology to capture images, but are not scanning systems which use the laser to create a pixel-by-pixel image. Instead, with time-of-flight devices, each pulse of the laser captures details from the entire viewed scene.
With time-of-flight devices, the image is of a lower resolution than traditional video cameras. This isn’t an issue, as the devices aren’t used for the identification of people, or for analysis of events. Instead the goal is to assess the presence of objects, based upon the characteristics of reflected light
Time-of-flight cameras with direct imaging can effectively create 3D footage, because the technology allows for the capture of spatial and temporal data. This is captured via a single flash from the laser-based light source.
Time of flight cameras might have a low resolution, but a fast capture rate of over 150fps, plus the ability to effectively create a 3D image, gives them a use in high-risk applications. Typically, where access control is a significant element of a security system in a critical application, interlocking door systems are deployed
In order for the security of such environments to be maintained, and this means it is vital that tail-gating and piggy-backing are accurately detected. This ensures that access and egress between an open area and a secure part of the site can be automatically managed
The time-of-flight camera can therefore identify multiple persons in a range of configurations (side-by-side, piggy-backing, etc.) and can differentiate between these and persons carrying objects, pushing trolleys or other innocuous activities
Accurance 3D is made up of a control box (A3001CB) and up to two time-of-flight sensors (A3001S). With a connection to the access control system, it scans an area of 1.5 x 1.5 metres between the two access doors, enabling access if only one person is present. Violations result in a denial of access
security is required. The control unit includes integral solid state storage to retain event information
Accurance 3D can be configured for two-way or one-way operation, depending upon whether bi-directional
Whilst the system is optimised for access control applications, software modifications can allow the introduction of additional features including people counting, object analysis, directional analysis and object left/removed detection.