Improved Salient Feature-Based Approach for Automatically Separating Photosynthetic and Nonphotosynthetic Components Within Terrestrial Lidar Point Cloud Data of Forest Canopies

• Published in: IEEE transactions on geoscience and remote sensing Vol. 54; no. 2; pp. 679 - 696
• Main Authors: Lixia Ma, Guang Zheng, Eitel, Jan U. H., Moskal, L. Monika, Wei He, Huabing Huang
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Accuracy; Animal behavior; Canopies; Classification; Eigenvalues and eigenfunctions; Forests; Laser radar; Leaf area index; Light detection and ranging (lidar); pattern recognition; Photosynthesis; point classification; Probability density function; Surface emitting lasers; terrestrial laser scanning (TLS); Three dimensional; Three-dimensional displays; Trees; Vegetation; woody-to-total area ratio; Light detection and ranging (lidar); woody-to-total area ratio; point classification; terrestrial laser scanning (TLS); pattern recognition
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/TGRS.2015.2459716

Accurate separation of photosynthetic and nonphotosynthetic components in a forest canopy from 3-D terrestrial laser scanning (TLS) data is a challenging but of key importance to understand the spatial distribution of the radiation regime, photosynthetic processes, and carbon and water exchanges of the forest canopy. The objective of this paper was to improve current methods for separating photosynthetic and nonphotosynthetic components in TLS data of forest canopies by adding two additional filters only based on its geometric information. By comparing the proposed approach with the eigenvalues plus color information-based method, we found that the proposed approach could effectively improve the overall producer's accuracy from 62.12% to 95.45%, and the overall classification producer's accuracy would increase from 84.28% to 97.80% as the forest leaf area index (LAI) decreases from 4.15 to 3.13. In addition, variations in tree species had negligible effects on the final classification accuracy, as shown by the overall producer's accuracy for coniferous (93.09%) and broadleaf (94.96%) trees. To remove quantitatively the effects of the woody materials in a forest canopy for improving TLS-based LAI estimates, we also computed the "woody-to-total area ratio" based on the classified linear class points from an individual tree. Automatic classification of the forest point cloud data set will facilitate the application of TLS on retrieving 3-D forest canopy structural parameters, including LAI and leaf and woody area ratios.