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New Zealand Aerial Mapping has recently commenced operating a new Optech ALTM airborne laser scanner. The unit has an integrated waveform digitiser, which records the complete energy return detected by the sensor.

NZAM is one of the world's oldest mapping companies. It was founded 70 years ago. It operates across the region - recently in East Timor and Nepal. It is also active in the Middle East and in the Pacific Islands.

The company has operated laser scanners for some time. Normally, these systems operate by returning the time light takes to travel from the sensor to its target. In an airborne sensor, this almost always means from the aircraft to the ground.

As the laser scans from side to side, this information makes it possible to calculate the distance from the aircraft to many thousands of spots on the ground. In this way, a laser scanner builds up a picture of the shape of the Earth under the plane.

An extension of this idea is to measure the intensity of the return. Customers like this facility, because it makes it possible to infer something about the surface at that point.

Capturing the entire waveform is simply an extension of this idea, although it is much more difficult to do.

Software algorithms are required to analyse the data. They makes it possible to discriminate targets in very close proximity provided they generate different waveforms. Also, it is possible to recover data about the roughness of the target or the slope of the terrain.

This may be beneficial when ranging to extended targets or through complex structures such as vegetation.

Visit www.nzam.com for more information.

ASM Newsletter is distributed by e-mail every two weeks. It reports on events in the spatial industry in Asia and events outside the region which will impact on Asia.