Development of LiDAR Data Classification Algorithms based on Parallel Computing using nVidia CUDA Technology

摘要

The paper presents an innovative data classification approach based on parallel computing performed on a GPGPU (General-Purpose Graphics Processing Unit). The results shown in this paper were obtained in the course of a European Commission-funded project: "Research on large-scale storage, sharing and processing of spatial laser data", which concentrated on LIDAR data storage and sharing via databases and the application of parallel computing using nVidia CUDA technology. The paper describes the general requirements of nVidia CUDA technology application in massive LiDAR data processing. The studied point cloud data structure fulfills these requirements in most potential cases. A unique organization of the processing procedure is necessary. An innovative approach based on rapid parallel computing and analysis of each point's normal vector to examine point cloud geometry within a classification process is described in this paper. The presented algorithm called LiMON classifies points into basic classes defined in LAS format: ground, buildings, vegetation, low points. The specific stages of the classification process are presented. The efficiency and correctness of LiMON were compared with popular program called Terrascan. The correctness of the results was tested in quantitive and qualitative ways. The test of quality was executed on specific objects, that are usually difficult for classification algorithms. The quantitive test used various environment types: forest, agricultural area, village, town. Reference clouds were obtained via two different methods: (1) automatic classification using Terrascan, (2) manually corrected clouds classified by Terrascan. The following coefficients for quantitive testing of classification correctness were calculated: Type 1 Error, Type 2 Error, Kappa, Total Error. The results shown in the paper present the use of parallel computing on a GPGPU as an attractive route for point cloud data processing.