By dr ir Mathias Lemmens, contributing editor

This is our third product review on airborne Lidar sensors. The second was published in February 2007 and the first under the title ‘Airborne Laser-scanners' in May 2004.

Airborne Lidar has matured to an accurate technology for the highly automated capturing of terrain data through xyz point clouds. "Mature" means that improvements are no longer founded on major technological breakthroughs, but are incremental. Lately the steps comprise full waveform digitisation, multiple pulses in air, and increased accuracy resulting from enhanced GNSS positioning and INS attitude determination.

Manufacturers are coming from two opposite directions: system building versus service provision. System builders include Leica Geosystems and Optech Inc., but most conspicuous is Riegl. Until late 2006, the latter was a manufacturer for manufacturers only, offering ‘laser sensors for airborne applications but not complete airborne Lidar systems,' as our 2004 survey notes to explain the many N/As in the columns. But in the 2007 survey, Riegl presented its full-fledged systems LMS-S560 and LMS-Q560. On the service provision side is Fugro, listed in the 2007 survey. Like TopEye and Terrapoint, Fugro developed its own in-house system, Flimap. The system has been regular and is

designed for corridor mapping using helicopters.

When manufacturers cross the line, differences become more diffuse. German company TopoSys combines manufacturing with self-executed surveys and considers this dual role as a base for expertise. Product features are quite similar to those of the Riegl systems even in name: LMS-Q560 vs Harrier 56 and LMS-Q680 vs Harrier 68; indeed, the core of the TopoSys systems are Riegl sensors. This is also true for German firm IGI's airborne Lidar terrain mapping system LiteMapper, which was listed in the 2007 survey. TopEye, listed in both the 2004 and 2007 surveys, was initially both a system builder and a service provider. With its origins in Swedish company Saab, TopEye became part of the Blom Group - which uses the technology for geodata collection - in July 2005.

Another Saab development is a system for hydrographic and topographic surveys. In 2002, Saab sold the rights for the system to tree former employees who launched Airborne Hydrography. The company is listed in our product overview for the first time, with its Dragon Eye topographic Lidar sensor and Hawk Eye II bathymetry and topography airborne laser system.