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Mathematical Problems in Engineering
Volume 2015, Article ID 206108, 14 pages
http://dx.doi.org/10.1155/2015/206108
Research Article

Study of Subtropical Forestry Index Retrieval Using Terrestrial Laser Scanning and Hemispherical Photography

1School of Information Science & Technology, Nanjing Forestry University, Nanjing 210037, China
2Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences, Danzhou 571737, China
3Joint Center Sustainable Forestry Studies in Southern China, Nanjing Forestry University, Nanjing 210037, China
4Advanced Analysis and Testing Center, Nanjing Forestry University, Nanjing 210037, China
5College of Forestry, Nanjing Forestry University, Nanjing 210037, China

Received 22 October 2014; Revised 13 February 2015; Accepted 4 March 2015

Academic Editor: Chih-Cheng Hung

Copyright © 2015 Ting Yun et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In order to retrieve gap fraction, leaf inclination angle, and leaf area index (LAI) of subtropical forestry canopy, here we acquired forestry detailed information by means of hemispherical photography, terrestrial laser scanning, and LAI-2200 plant canopy analyzer. Meanwhile, we presented a series of image processing and computer graphics algorithms that include image and point cloud data (PCD) segmentation methods for branch and leaf classification and PCD features, such as normal vector, tangent plane extraction, and hemispherical projection method for PCD coordinate transformation. In addition, various forestry mathematical models were proposed to deduce forestry canopy indexes based on the radiation transfer model of Beer-Lambert law. Through the comparison of the experimental results on many plot samples, the terrestrial laser scanner- (TLS-) based index estimation method obtains results similar to digital hemispherical photograph (HP) and LAI-2200 plant canopy analyzer taken of the same stands and used for validation. It indicates that the TLS-based algorithm is able to capture the variability in LAI of forest stands with a range of densities, and there is a high chance to enhance TLS as a calibration tool for other devices.