Network Pan Tilt Zoom cameras continue to evolve as manufacturers combine the advantages of digital technology with the best conventional PTZ features and performance qualities. A class of high performance products is emerging to challenge their analog counterparts to compete in demanding security installations.
Many early and current network PTZ offerings are limited in performance, quality and durability. In fact, many network PTZ cameras seem to be designed as network and video encoding devices first and foremost with high quality mechanical and precision control devices as a secondary consideration. This position has created the perception that network cameras are not able to satisfy the requirements for demanding applications.
Things have changed.
What's New?
Applications for airports, seaports and casinos all require the ability to follow moving objects from long distances. A class of high performing network PTZ products is designed to meet this need at dealer prices ranging from $2,000 to $2,500. What are some of the attributes found in these products?
Design for Continuous Operation – Network PTZ cameras such as the Axis 233D, Panasonic's new NS-954 model and Sony's RX550N are designed for continuous pan operation. According to Steve Surfaro, Panasonic System Solutions, the new Panasonic NS-954 uses the same packaging, optical slip ring assembly and heavy duty drive mechanisms used in the Panasonic industrial analog camera line.
Full 360 degree motion - Axis's 233D and Sony's SNC-RX550N are designed to provide full 360 pan motion.
Optical Zoom - Powers of 35x (Axis 233D) 30x (Panasonic NS-964) and 26x (Sony RX550N) meet or exceed the optical zoom power of most conventional analog cameras.
Electronic Image Stabilization (EIS) - The vibration effect from poles, bridges and buildings is amplified as the optical zoom power increases. EIS reduces the effects of vibration.
Wide Dynamic Range - Wide Dynamic ranges of up to 128X ensure high-quality video that maintains contrast in complex lighting conditions that combine bright sun, reflections and shaded areas.
Image Hold - Image hold will freeze the image as the camera pans between presets. This not only makes the camera images easier to view, it can lower the average data-rate and storage requirement for moving video. MPEG-4 data rates are significantly higher for high motion video.
Full Duplex Audio - Full duplex audio can be used to implement an intercom system to remotely communicate with intruders or visitors.
Flash Drive - Sony (Memory Stick) and Panasonic (SD Memory) models write video to a portable flash memory (SD Memory or Memory Stick) in the event of a network outage.
What about precision control?
Historically, the Achilles heel of network PTZ performance has been control. High precision control with network cameras can be a frustrating exercise due to the limitations of the camera, the controlling software or the network.
A well-designed local area network should not introduce significant latencies that impact precision control. This leaves the interaction of the camera and the controlling system as the most significant factors.
The Axis 233D has a pan speed range of 0.05 to 450 degrees per second. According to Fredrik Nilsson, General Manager of Axis Communications, Axis recognized the challenge of precision control and focused on improving both the internal camera firmware and the software components that are provided to software partners. Nilsson also cites the advantages of using a single processing engine to host the networking, image analysis and PTZ control firmware. This tight coupling has allowed Axis to significantly improve the precision of camera control.
E-flip functionality inverts the video by 180 degrees to allow an operator to easily follow an object moving directly under the dome.
What's Next?
Power over Ethernet Plus (PoE-Plus) – Most PTZ cameras do not support the current 802.3af PoE standard that is widely supported by fixed network cameras. The pan-tilt motors (not including heaters and fans) simply have power requirements (15-20 Watts) that exceed the current 12.95 Watts defined by the standard.
Help is on the way! The IEEE is at work to create a new standard: PoE-Plus or IEEE 802.3at. The original goal of the standard was to deliver at least 30W to each network device. By the time the standard is finalized next year, the power specification may be close to 60W per device while maintaining backward compatibility with the current 802.3af standard. Once PoE-Plus is adopted, new network PTZ products will combine audio, video, control, power and relay signals over a single CAT5 cable.
Intelligence – Analytic features such as object tracking will improve and evolve to provide automatic panning and tilting to track moving objects.
Finally, Megapixel resolutions will inevitably appear in future PTZ products. The combination of higher resolutions, progressive scan images and increasing optical zoom powers will provide new levels of video clarity that will be impossible to achieve with conventional NTSC/PAL products.
Tom Galvin of NetVideo Consulting is a network video specialist. NetVideo Consulting (www.netvideoconsulting.com) provides product evaluations, training programs and software tools to enable successful networked video solutions.
