The idea of using a computer network or the Internet to distribute live video images dates back to at least the early 1990s. However, the key development, which made network IP cameras practically and commercially viable, was to integrate a video camera with video server to create a fully self-contained surveillance device, and credit for this almost certainly belongs to Axis Communications for its model 200 IP camera, launched in mid 1996.
Eleven and a bit years later and Axis are still leading the way in network camera technology, this time with the 233D network dome camera. This model boasts an impressive line up of features, which puts many conventional dome cameras to shame. These include a powerful 35x optical zoom, supplemented with a 12x digital zoom for some impressive close-ups of distant objects. Axis claims vehicle number plates can be clearly read at distances of 160 metres (525 feet) or more.
It’s a pukka day/night camera with a switchable IR cut filter. It is based around a .25-inch ExView HAD progressive scan CCD. This has a minimum sensitivity of 0.5 lux in colour mode and 0.008 lux in monochrome night mode. Five resolution options are available, from 704 x 576 down to 176 x 144 (4CIF, 2CIFxp, 2CIF, CIF and QCIF) at up to 30 fps, which a claimed maximum horizontal resolution of 540 lines.
It supports simultaneous streaming of JPEG and MPEG-4 images and an electronic image stabiliser smoothes out judder and vibration. A ‘flip’ mode turns the image through 180 degrees when a subject passes beneath the camera dome. The image can also be inverted manually for bench testing.
There’s a good assortment of picture adjustments and manual exposure controls (colour, brightness, sharpness, wide dynamic range, exposure area, gain, shutter speed, low light behaviour etc) these are in addition to the usual range of auto systems. It has pre and post alarm buffers for storing images, there’s a two-way (full or half-duplex) audio capability, and up to 20 network users can view images from the camera simultaneously.
A nifty feature that we’ve seen before on Axis cameras, called ‘Area Zoom’, helps to alleviate one of the main problems associated with network ‘lag’ when it comes to controlling the PTZ mechanism. To zoom in on an area or subject all the operator has to do is ‘draw’ a square around it using the mouse pointer.
The alternative is ’emulated joystick’ control, which turns the mouse into a virtual joystick, so all the user has to do is click and move the pointer to a point on the screen; pan/tilt speed is controlled by the distance the pointer is from the centre of the screen. It has a privacy mask facility, motion sensing, audio and external alarm triggering, image upload via FTP, HTTP and email and email event notification.
On the mechanical side the precision pan/tilt mechanism operates at speeds of between 0.05 to 450 degrees per second, and it will move to any preset position in under 1.5 seconds.
From the outside there’s nothing to suggest this is a network camera, or indeed anything other than a normal dome camera. The case is made from a tough alloy and very well protected against the elements. The top of the unit is a little unusual in that the input and output connections are housed in an odd-looking metal box structure.
Three multi-pin sockets are mounted in a row on one face of the box. The first two are used for alarm input and output connections whilst the third carries power (18-30vAC or 22-40vDC), line audio out and microphone input. A standard Ethernet socked is mounted in a small metal box on the side.
The PTZ mechanism is built on a sturdy cast alloy chassis. A pair of stepper motors turns and tilts the camera using two sets of belt driven reduction gears. The camera module is mounted inside a curved cylindrical housing and connects to a single PCB through a pair of ribbon cables. The standard of construction appears to be of a high order and the simplicity of the mechanics suggests that reliability should be very good.
Setup and operation
Image display and communications to the 233D is via standard web browsers (Internet Explorer 6 or later and, we’re pleased to say, Mozilla Firefox as well, though not all controls options are available on the latter). A supplied utility on an accompanying CD ROM – which also includes extensive documentation in the form of pdf files – locates the camera on the network and allows the user to change the IP address from the factory default and set up an administrator password. Once that’s done the main viewer window opens to display the live camera view plus a set of pan and tilt sliders and controls for zoom and focus.
This also allows access to the camera’s setup menus and Help files. Active-X plugs are required in order to display the M-JPEG and MPEG-4 streams but these are installed with just a couple of clicks of the mouse (though we did experience some difficulty installing the MPEG4 decoder in Firefox but we put this down to idiosyncrasies in our setup).
The first page of the Setup menu opens with a mixture of sub menu options. The first item is Basic Configuration, which covers user names and groups, TCP/IP settings, date and time, video and Image setup (resolution, compression, on-screen indications, video stream and test mode), and audio (mode, input source, gain, encoding, bitrate, alarm level and audio output).
The second item is called Video Image, and this has additional sub menus for uploading a custom overlay/background image, defining the privacy masks and an Advanced menu for setting colour level, brightness, sharpness, exposure, controlling the IR cut filter, wide dynamic range backlight compensation, low light modes, focus, image stabiliser and image freeze (during PTZ movement).
The main Audio menu follows a similar pattern with extra options for enabling a speech filter, echo cancellation and noise attenuation.
Next on the list is Live View Configuration which contains a number of options for customising the look and layout of the main display windows, allowing the user to include links to web pages, hide or show various buttons and change things like video format, tool bars and a crosshair in the image display (for the Area Zoom feature).
On the Dome Configuration menu there are sub menus for setting preset positions, creating a Tour, displaying an OSDI (On-screen Directional Indicator for defined zones), adjusting PTZ limits, labelling shortcut command buttons and limiting the number of users and setting queue times.
Event Configuration is responsible for setting up Event Servers, creating an Event Type/Action list, setting up motion detection and displaying Port Status.
Finally the System Options sub menu, which again duplicates parts of the Basic Configuration menu (users, date and time etc) and includes extra selections for IP address filtering, secure HTTPS and 802.1x settings, detailed network configuration, ports and devices, maintenance (reboot, restore defaults, status, test, firmware upgrade, backup and restore).
One particularly impressive feature of what is a very detailed set of setup menus is the context sensitive Help facility. Clicking the Help button brings up an easy to follow explanation and instructions that relate directly to the page or section of the menu in use, making the printed and pdf versions of the manual almost (but not quite) redundant.
Normal day-to-day operations using the main viewer window couldn’t be simpler and apart from the inevitable delays brought about by network operation it’s as easy to use as a convention dome and it can be made even simpler with the addition of an optional Axis 295 USB joystick controller. The only small gripe concerns the Area Zoom, which works superbly well, but it lacks an equally direct means of zooming back out or returning to the previous zoom setting. We did discover – almost by accident – that the zoom is linked to a ‘wheel mouse’ scroll wheels, though this is quite slow and for some reason this wasn’t very responsive, or reliable on our setup.
Performance
The powerful zoom is a major benefit on this model, and coupled with the high performance image sensor and processing electronics, picture performance is quite simply excellent. At the higher resolution settings and with the exposure controls on automatic M-JPEG images are very well balanced, they contains a lot of useful detail, noise levels are negligible, colours are natural looking, and it responds quickly to changes in lighting levels.
Even on a full screen view, which is pushing the technology to its limits, the drop in quality is marginal; sharp edges become a little ragged and this gets progressively worse at the lower resolution settings, but it is still very useable.
The only downside to network operation is the brief delay in issuing a PTZ command and something happening. The emulated joystick mode also takes some getting used to and we found it quite difficult to control at times. No doubt with practice it can be mastered but the combination of network delays and at times an erratic response to instructions makes tracking a moving object or subject quite challenging.