We currently operate with up to five industrial quality digital cameras, mounted in any directional configuration on a host vehicle. The video collection system is small and portable, meaning that a wide variety of host vehicles could be used. For example:

• Truck
• Bus
• Tram
• Train (either rail car or maintenance car)
• Golf Cart (for cycleways and foot paths)

The common requirements are that a power supply be available and that access to mounting the cameras and odometer is possible.

The cameras use the versatile IEEE1394 (FireWire) interface with the host computer. The cameras operate well in varying and low light conditions, at all times maintaining high shutter speeds to eliminate motion blur. We have developed our own systems for monitoring light levels and responding to changing conditions as quickly as possible to minimise poor exposure on images. This is an important consideration for mobile surveys which may be performed at considerable speed.

Various cameras are available with individual image resolutions of:

• 640 x 480
• 768 x 576 (broadcast quality)
• 1024 x 768
• 1392 x 1040 pixels

Different combinations are possible, to ensure an appropriate trade-off between image clarity and image storage size. Customised image compression algorithms maintain image clarity in difficult conditions, while keeping file size to a manageable 70Kb per image (based on a 768x576 pixel image size).

Image capture and survey position are determined by precision odometer and GPS location equipment. Images are triggered by distance events to ensure that capture from each camera is consistent with the survey plan for the asset section.

We use a custom developed electronic hardware-based image capture trigger. This trigger device is accurate enough at synchronising the image capture, that we can make panoramic views from collections of cameras, even when testing at high speed (100km/hr). These panoramic scenes offer unique views of the asset and highly versatile approaches to post-rating from the images.

Our in-house software systems enable detailed inventory and condition analysis of the images by our trained rating staff. Objects in the images can be measured using an on screen measurement tool, classified by any combination of object type and sub-class and visually assessed for condition.

Imagery can be provided via the internet, network attached storage (NAS), on DVD or removable (USB/FireWire) hard disk drive. Interpreted inventory and condition data can be provided in most file or database formats.