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Extraction of buildings from high-resolution satellite data and airborne Lidar

Automatic building extraction is a difficult object recognition problem due to a high 
complexity of the scene content and the object representation. There is a dilemma to 
select appropriate building models to be reconstructed; the models have to be generic in 
order to represent a variety of building shape, whereas they also have to be specific to 
differentiate buildings from other objects in the scene. Therefore, a scientific challenge 
of building extraction lies in constructing a framework for modelling building objects 
with appropriate balance between generic and specific models. This thesis investigates a 
synergy of IKONOS satellite imagery and airborne LIDAR data, which have recently 
emerged as powerful remote sensing tools, and aims to develop an automatic system, 
which delineates building outlines with more complex shape, but by less use of 
geometric constraints. 
The method described in this thesis is a two step procedure: building detection and 
building description. A method of automatic building detection that can separate 
individual buildings from surrounding features is presented. The process is realized in a 
hierarchical strategy, where terrain, trees, and building objects are sequentially detected. 
Major research efforts are made on the development of a LIDAR filtering technique, 
which automatically detects terrain surfaces from a cloud of 3D laser points. The thesis 
also proposes a method of building description to automatically reconstruct building 
boundaries. A building object is generally represented as a mosaic of convex polygons. 
The first stage is to generate polygonal cues by a recursive intersection of both datadriven 
and model-driven linear features extracted from IKONOS imagery and LIDAR 
data. The second stage is to collect relevant polygons comprising the building object 
and to merge them for reconstructing the building outlines. The developed LIDAR filter 
was tested in a range of different landforms, and showed good results to meet most of 
the requirements of DTM generation and building detection. Also, the implemented 
building extraction system was able to successfully reconstruct the building outlines, 
and the accuracy of the building extraction is good enough for mapping purposes.