Semantic segmentation of urban airborne LiDAR data of varying landcover diversity using XGBoost

Abstract

Semantic segmentation of aerial LiDAR dataset is a crucial step for accurate identification of urban objects for various applications pertaining to sustainable urban development. However, this task becomes more complex in urban areas characterised by the coexistence of modern developments and natural vegetation. The unstructured nature of point cloud data, along with data sparsity, irregular point distribution, and varying sizes of urban objects, presents challenges in point cloud classification. To address these challenges, development of robust algorithmic approach encompassing efficient feature sets and classification model are essential. This study incorporates point-wise features to capture the local spatial context of points in datasets. Furthermore, an ensemble machine learning model based on extreme boosting is utilised, which integrates sequential training for weak learners, to enhance the model’s resilience. To thoroughly investigate the efficacy of the proposed approach, this study utilises three distinct datasets from diverse geographical locations, each presenting unique challenges related to class distribution, 3D terrain intricacies, and geographical variations. The Land-cover Diversity Index is introduced to quantify the complexity of landcover in 3D by measuring the degree of class heterogeneity and the frequency of class variation in the dataset. The proposed approach achieved an accuracy of 90% on the regionally complex, higher landcover diversity dataset, Trivandrum Aerial LiDAR Dataset. Furthermore, the results of the study demonstrate improved overall predictive accuracy of 91% and 87% on data segments from two benchmark datasets, DALES and Vaihingen 3D.