1. Associate Professor, Dept. of Civil Engineering/LIDAR Center, National Taipei Univ. of Technology, Sect. 3, Zhong-Xiao E. Rd., Taipei 106, Taiwan (corresponding author).
2. Professor, Dept. of Civil Engineering, National Taiwan Univ., Sect. 4, Roosevelt Rd., Taipei 106, Taiwan.
3. Associate Professor, Dept. of Computer Science and Information Engineering/LIDAR Center, National Taipei Univ. of Technology, Sect. 3, Zhong-Xiao E. Rd., Taipei 106, Taiwan.