A simple technique for co-registration of terrestrial LiDAR observations for forestry applications

Abstract

Light detection and ranging (LiDAR) from terrestrial platforms provides unprecedented detail about the three-dimensional structure of forest canopies. Although airborne laser scanning is designed to yield a relatively homogeneous distribution of returns, the radial perspective of terrestrial laser scanning (TLS) results in a rapid decrease of number of returns with increasing distance from the instrument. Additionally, when used in forested environments, significant parts of the area under investigation may be obscured by tree trunks and understorey. A possible approach to mitigate this effect is to combine TLS observations acquired at different locations to obtain multiple perspectives of an area under investigation. The denser and more evenly distributed observations then allow a spatially explicit and more comprehensive study of forest characteristics. This study demonstrates a simple approach to combine TLS observations made at multiple locations using bright reference targets as tie-points. Results show this technique was able to accurately combine the different TLS data sets (root mean square error (RMSE): 0.04–0.7 m, coefficient of determination (R ²): 0.70–0.99). Terrain elevations from TLS system were highly correlated with field-measured terrain heights (R ²: 0.70–0.98).

Acknowledgements

Past and current members of the Integrated Remote Sensing Studio, Faculty of Forest Resources Management, University of British Columbia, are thanked for their assistance with the field work. This work is partially funded by an NSERC Discovery grant to Coops. Additional funding support was also received from the Canadian Wood Fibre Centre, of the Canadian Forest Service of Natural Resources Canada.