Defence of dissertation in the field of remote sensing, M.Sc. (Tech.) Lingli Zhu
A Pipeline for 3D Scene Reconstruction from Point Clouds.
The public examination of the doctoral dissertation of M.Sc. (Tech.) Lingli Zhu will be held on 18 June 2015 at 12.00 at the Aalto University School of Engineering. The title of the dissertation is A Pipeline for 3D Scene Reconstruction from Point Clouds.
Venue: Lecture hall M1, Otakaari 1, Espoo
3D technologies are becoming increasingly popular as their applications in industrial, consumer, entertainment, healthcare, education, and governmental increase in number. According to market predictions, the total 3D modeling and mapping market is expected to grow from $1.1 billion in 2013 to $7.7 billion by 2018. Thus, 3D modeling techniques for different data sources are urgently needed.
This thesis addresses techniques for automated point cloud classification and the reconstruction of 3D scenes (including terrain models, 3D buildings and 3D road networks). First, georeferenced binary image processing techniques were developed for various point cloud classifications. Second, robust methods for the pipeline from the original point cloud to 3D model construction were proposed. Third, the reconstruction for the levels of detail (LoDs) of 1-3 (CityGML website) of 3D models was demonstrated. Fourth, different data sources for 3D model reconstruction were studied. The strengths and weaknesses of using the different data sources were addressed. Mobile laser scanning (MLS), unmanned aerial vehicle (UAV) images, airborne laser scanning (ALS), and the Finnish National Land Survey’s open geospatial data sources e.g. a topographic database, were employed as test data. Among these data sources, MLS data from three different systems were explored, and three different densities of ALS point clouds (0.8, 8 and 50 points/m2) were studied.
The results were compared with reference data such as an orthophoto with a ground sample distance of 20cm or measured reference points from existing software to evaluate their quality. The results showed that 74.6% of building roofs were reconstructed with the automated process. The resulting building models provided an average height deviation of 15 cm. A total of 6% of model points had a greater than one-pixel deviation from laser points. A total of 2.5% had a deviation of greater than two pixels. The pixel size was determined by the average distance of input laser points. The 3D roads were reconstructed with an average width deviation of 22 cm and an average height deviation of 14 cm. The results demonstrated that 93.4% of building roofs were correctly classified from sparse ALS and that 93.3% of power line points are detected from the six sets of dense ALS data located in forested areas.
This study demonstrates the operability of 3D model construction for LoDs of 1-3 via the proposed methodologies and datasets. The study is beneficial to future applications, such as 3D-model-based navigation applications, the updating of 2D topographic databases into 3D maps and rapid, large-area 3D scene reconstruction.
Opponents: Professor Dr. Stephan Nebiker, University of Applied Sciences and Arts Northwestern, Sveitsi and Professor Dr.-Ing. Norbert Haala, University of Stuttgart, Germany
Supervisor: Professor Henrik Haggrén, Aalto University School of Engineering, Department of Real Estate, Planning and Geoinformatics.
Electronic dissertation thesis: https://aaltodoc.aalto.fi/handle/123456789/16214
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