Laser scanning of forest resources: the nordic experience

Abstract

This article reviews the research and application of airborne laser scanning for forest inventory in Finland, Norway and Sweden. The first experiments with scanning lasers for forest inventory were conducted in 1991 using the FLASH system, a full-waveform experimental laser developed by the Swedish Defence Research Institute. In Finland at the same time, the HUTSCAT profiling radar provided experiences that inspired the following laser scanning research. Since 1995, data from commercially operated time-of-flight scanning lasers (e.g. TopEye, Optech ALTM and TopoSys) have been used. Especially in Norway, the main objective has been to develop methods that are directly suited for practical forest inventory at the stand level. Mean tree height, stand volume and basal area have been the most important forest mensurational parameters of interest. Laser data have been related to field training plot measurements using regression techniques, and these relationships have been used to predict corresponding properties in all forest stands in an area. Experiences from Finland, Norway and Sweden show that retrieval of stem volume and mean tree height on a stand level from laser scanner data performs as well as, or better than, photogrammetric methods, and better than other remote sensing methods. Laser scanning is, therefore, now beginning to be used operationally in large-area forest inventories. In Finland and Sweden, research has also been done into the identification of single trees and estimation of single-tree properties, such as tree position, tree height, crown width, stem diameter and tree species. In coniferous stands, up to 90% of the trees represented by stem volume have been correctly identified from canopy height models, and the tree height has been estimated with a root mean square error of around 0.6 m. It is significantly more difficult to identify suppressed trees than dominant trees. Spruce and pine have been discriminated on a single-tree level with 95% accuracy. The application of densely sampled laser scanner data to change detection, such as growth and cutting, has also been demonstrated.

Keywords:

• Airborne laser scanning
• canopy height
• forest inventory
• timber volume
• tree segmentation

Notes

Næsset, E. ¹ , Gobakken, T. ¹ , Holmgren, J. ² , Hyyppä, H. ³ , Hyyppä, J. ⁴ , Maltamo, M. ⁵ , Nilsson, M. ² , Olsson, H. ² , Persson, Å. ⁶ and Söderman, U. ⁶ (¹Department of Ecology and Natural Resource Management, NLH, P.O. Box 5003, NO-1432 Ås, Norway, ²Department of Forest Resources Management and Geomatics, SLU, SE-90183 Umeå, Sweden, ³Institute of Photogrammetry and Remote Sensing, Helsinki University of Technology, FI-02015 HUT, Finland, ⁴Department of Remote Sensing and Photogrammetry, Finnish Geodetic Institute, FI-02431 Masala, Finland, ⁵Faculty of Forestry, University of Joensuu, Finland, and ⁶Department of Laser Systems, Swedish Defence Research Agency, P.O. Box 1165, SE-58111 Linköping, Sweden). Laser scanning of forest resources: the Nordic experience.

Additional information

Notes on contributors

Erik Næsset

Næsset, E. 1 , Gobakken, T. 1 , Holmgren, J. 2 , Hyyppä, H. 3 , Hyyppä, J. 4 , Maltamo, M. 5 , Nilsson, M. 2 , Olsson, H. 2 , Persson, Å. 6 and Söderman, U. 6 (1Department of Ecology and Natural Resource Management, NLH, P.O. Box 5003, NO-1432 Ås, Norway, 2Department of Forest Resources Management and Geomatics, SLU, SE-90183 Umeå, Sweden, 3Institute of Photogrammetry and Remote Sensing, Helsinki University of Technology, FI-02015 HUT, Finland, 4Department of Remote Sensing and Photogrammetry, Finnish Geodetic Institute, FI-02431 Masala, Finland, 5Faculty of Forestry, University of Joensuu, Finland, and 6Department of Laser Systems, Swedish Defence Research Agency, P.O. Box 1165, SE-58111 Linköping, Sweden). Laser scanning of forest resources: the Nordic experience.