Building 3D Detection and Extraction in Informal Settlement Areas

Author: Marcelo Teixeira Silveira

Original title: Detecção e Extração 3D de Edificações em Áreas de Assentamentos Informais

Language: Brazilian Portuguese

Electronic version: Portuguese English

Abstract

Informal settlements in many Brazilian urban centers are growing up
quickly. Remote Sensing techniques provide a cost-effective mean to measure
such an expansion. In cities with rough topography, like the city of Rio de Janeiro,
the initial expansion, predominantly horizontal, is gradually being shifted to
vertical, as new floors are being built on the existing buildings. To estimate the
changing of such type of buildings, 3D measuring techniques are required. This
research proposes a method for generating Digital Surface Model (DSM) from
digital photogrammetry techniques. The method takes an initial DSM calculated
from a pair of stereoscopic images as input. These models have no knowledge of
image scenes semantics. The input DSM is refined taking into account the
information about the geometry of buildings identified by a process of
segmentation and interpretation applied to both images of the stereo pair. The
method is based on a priori knowledge that buildings from informal settlements in
large urban centers in Brazil generally have their roof tops at approximately
constant height (flat roofs). The process involves three main steps: firstly the tops
of buildings are identified in each pair of stereoscopic images. Then, the regions
corresponding to the top of the buildings are matched. The third step involves the
3D extraction of those buildings. Finally, the method generates a more accurate
DSM plus an image label with the semantics of the identified buildings. The
results obtained in the experiments on airborne imagery of a test area in the city of
Rio de Janeiro showed a significant improvement in the original DSM, as it takes
into account the semantics of the 3D reconstructed buildings.