The migration to IP from analog affects dome performance. High-resolution cameras, fisheye lenses and network constraints influence optimal dome operation.
Higher resolution dome cameras enable greater detail, but also introduce network issues. In turn, networks facilitate greater connectivity, but may also incur lag. One consideration for IP devices is the cabling distance, which was rarely an issue for analog, said Andrew Pigram, Technical Director at Norbain.
The migration to IP from analog affects dome performance. High-resolution cameras, fisheye lenses and network constraints influence optimal dome operation.
Higher resolution dome cameras enable greater detail, but also introduce network issues. In turn, networks facilitate greater connectivity, but may also incur lag. One consideration for IP devices is the cabling distance, which was rarely an issue for analog, said Andrew Pigram, Technical Director at Norbain.
Latency for network dome controls is about 300 milliseconds, due to IP traffic constraints and compression requirements, said Ian Crosby, Product Marketing Manager for CCTV, Bosch Security Systems. This is barely discernible to operators but can be exacerbated if the network cannot withstand video surveillance traffic.
Big-Picture Domes
Network domes include newer megapixel and HD models, which provide greater image clarity but add to the processor load. Depending on what processor is used, a true high-resolution dome may have few other functions to prevent image lag, said Alf Chang, Senior Consultant for A&S magazines. A high-resolution dome may have to sacrifice image correction or analytics to free up processing power. The CPU will be taxed further if the dome offers dual or triple streaming, limiting the functional performance of high-resolution domes.
The top end for high-resolution domes is around 2-megapixel or 1080p HD, as real-time frame rates are still feasible. “The standard in HD is emerging as 720p, because 720p is 1.3-megapixel, which is still four times the image content of analog; so, it's pretty good,” Pigram said.
Low-light performance is another consideration for high-resolution cameras, with CCDs delivering consistent results. “They tend to be 1.3-megapixel in resolution,” Pigram said. “Four- or 5-megapixel technology tends not to be real-time and is typically more like 15 fps. High megapixel count might not be suitable for areas with a lot of movement or low light levels, as the price for resolution is sensitivity.”
Fine Detail
Despite resolution and processor constraints, more pixels do make a noticeable difference. “In many events, when the police went back through footage, the images were not usable,” said Allen Yang, PM at Etrovision Technology. “High-resolution cameras can do real identification.”
HD at 1080p increases the viewing area of standard definition (SD) by six times. “If you zoom in on a D1 image, you will get less detail, but full HD offers greater clarity,” said Garrett Li, Marketing Manager at DynaColor.
A single megapixel or HD camera can save installers time. “In surveillance, the highest cost is installation,” Yang said. “With a 5-megapixel dome, if you have a wide area, you just need one camera. It's expensive but replaces many D1 cameras and reduces installation costs.”