Panoramic camera has become very popular in video surveillance because of its wide angle field of view which significantly reduces the amount of cameras needed for complete video coverage. This brings total system cost saving benefits to the end user. There are two major technology trends in the next generation panoramic camera. The first trend is improving low lux performance by adding built-in IR illuminators so that the camera is able to record useful image even in challenging low light condition. The second trend is to run video content analysis (VCA) inside the camera to provide intelligent features.
IR Illumination for Panoramic Cameras Built-in IR illuminators have been widely used in many surveillance cameras to capture useful footages during nighttime. However, due to the nature of wide angle field of view, adding IR LEDs to the fisheye camera come with 2 sets of challenges. The first issue is correcting bad uniformity of the illumination, and the other is eliminating over exposure problem of the foreground objects.
The result of the traditional IR illumination looks like the following picture, the central area has much higher light density which is often refer to as “white out or glare”. This is due to the light-emitting pattern of the IR LED and the wide coverage of the fisheye lens. As result, the video captured by the panoramic camera using traditional IR LEDs will not have proper exposure level. The peripheral area tends to be too dark and if there is an object in the central region, it tends to be overly exposed.
VIVOTEK has developed a unique technology to solve this problem. Instead of using IR LEDs only, we added a reflector with precisely calculated surface to shape the IR lights so that the illumination gets evenly distributed across the entire view angle. The design of the reflector is illustrated in the following figure.
The following picture shows the modified illumination pattern after using the reflector. It is clear that the VIVOTEK unique IR technology is able to distribute illumination evenly without glare spot in the center.
With the specially designed built-in IR illuminators, IR solution has been optimized to fit the VIVOTEK fisheye camera's wide view angle and gives an even illumination across the entire area while the result from other brand shows “glare” spots in central region and dark peripheral, which is a waste of illumination power.
The following images demonstrate the advantage of VIVOTEK's unique IR technology compare to another manufacturer.