Laser mapping has helped researchers characterise forest stands in New Zealand. The team at Scion, a New Zealand Crown Research Institute (CRI), used handheld mobile laser scanners to locate and measuring individual trees on the ground for forest management purposes.
The team used the ZEB1, a laser scanner developed by CSIRO, Australia’s national science agency, which continuously scans as the operator walks through the environment. As the scanner loosely oscillates about a spring it produces a rotation that converts 2D laser measurements into 3D fields of view. Scion purchased the ZEB1 from 3D Laser Mapping, a global developer of laser scanning solutions for sectors such as mapping, mining and manufacturing.
The researchers scanned small stands of trees close to the Scion campus in Rotorua, New Zealand. They are now carrying out further trials of the system including the scanning of inventory plots used to characterise forest stands for management purposes. The project team aims to extract tree diameters, locations and stem shapes from the ZEB1 point clouds rather than through the use of conventional manual measurements.
ZEB1 is able to self-localise making it ideal for applications where there’s no GPS coverage. ‘Traditionally poor GPS under forest cover makes identifying trees a problem,’ commented David Pont of Scion, an award winning scientist who specialises in world leading research to identify individual trees from remotely sensed aerial lidar. ‘The ability of the ZEB1 to provide the position for spatial locations using SLAM technology – specifically developed for mapping of areas with no GPS – was therefore of immediate interest to us.
‘Besides portability and ease of use the ZEB1 really shines in the speed of scanning,' Pont continued. ‘In the forest, trees are obscured by terrain, undergrowth and even other trees and conventional tripod units require multiple scans and registration of the point cloud to cover any significant area. The ZEB1 scans continuously as you move around the forest to provide a single, registered point cloud.’
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