Abstract

Abstract. This paper presents an automated approach to the extraction of building footprints from airborne LiDAR data based on energy minimization. Automated 3D building reconstruction in complex urban scenes has been a long-standing challenge in photogrammetry and computer vision. Building footprints constitute a fundamental component of a 3D building model and they are useful for a variety of applications. Airborne LiDAR provides large-scale elevation representation of urban scene and as such is an important data source for object reconstruction in spatial information systems. However, LiDAR points on building edges often exhibit a jagged pattern, partially due to either occlusion from neighbouring objects, such as overhanging trees, or to the nature of the data itself, including unavoidable noise and irregular point distributions. The explicit 3D reconstruction may thus result in irregular or incomplete building polygons. In the presented work, a vertex-driven Douglas-Peucker method is developed to generate polygonal hypotheses from points forming initial building outlines. The energy function is adopted to examine and evaluate each hypothesis and the optimal polygon is determined through energy minimization. The energy minimization also plays a key role in bridging gaps, where the building outlines are ambiguous due to insufficient LiDAR points. In formulating the energy function, hard constraints such as parallelism and perpendicularity of building edges are imposed, and local and global adjustments are applied. The developed approach has been extensively tested and evaluated on datasets with varying point cloud density over different terrain types. Results are presented and analysed. The successful reconstruction of building footprints, of varying structural complexity, along with a quantitative assessment employing accurate reference data, demonstrate the practical potential of the proposed approach.

Highlights

  • Building footprints are important features in spatial information systems and they are used for a variety of applications, such as visual city tourism, urban planning, pollution modelling and disaster management

  • This paper has presented a novel energy minimization based method for building footprint extraction from airborne LiDAR data

  • Different forms of energy minimization are formulated to determine the optimal polygon among various hypotheses, and to bridge gaps between consecutive line segments through optimal connectors

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Summary

Introduction

Building footprints are important features in spatial information systems and they are used for a variety of applications, such as visual city tourism, urban planning, pollution modelling and disaster management. In cadastral datasets, building footprints are a fundamental component. They define a region of interest (ROI), and reveal valuable information about the general shape of building roofs. Building footprints can be employed as a priori shape estimates in the modelling of more detailed roof structure (Vosselman, 2002). Often cited approaches to building footprint determination can be found in Lafarge et al (2008), Vosselman (1999) and Weidner and Förstner (1995)

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