Abstract: Due to large volume of data, uneven spatial distribution of point densities, and complex scene, it is difficult to automatically extract and delineate road boundaries from mobile laser scanning (MLS) point clouds. This paper proposed a method for extracting road boundaries from MLS point clouds based on Snake. Different from the traditional Snake model defined within 2D image, we modified the Snake model directly based on 3D point clouds. Firstly, we developed a way of initializing Snake curves using pseudo-trajectory data to match multi-type road boundaries. Then, the Snake’s energy function was designed with internal, external and constrained energy terms derived from Snake curve points with their neighborhood points. Finally, the road boundaries were precisely extracted by minimizing the Snake’s energy function. Experiments were undertaken to evaluate the validities of the proposed algorithm with three different urban scene datasets acquired by different MLS system. Quantitative evaluations on the selected MLS datasets indicate that the Precision, Recall and F₁-Measure of road boundaries extraction results were over 97.62%, 98.04%, 97.83%, respectively, which validate that the proposed method proved a promising and robust solution for regular and irregular road boundaries extraction in complex urban environments.

Key words: mobile laser scanning point clouds, active contour model (Snake), road boundaries extraction, gradient vector, energy function