The identification and localization of buildings in an ur-
ban area is very important for planning, building analysis,
automatic 3D reconstruction of building models and change
detection (Qin and Gruen, 2014). The development of very
high resolution (VHR) remote sensing images (Qin et al., 2013)
creates a possible avenue to sense individual buildings in
an urban scenario, e.g., Ikonos with 1-meter resolution, or
Worldview with 0.5-meter resolution. Sensors with even
higher resolution are in the planning stages (e.g., Geoeye-2
and Worldview-3 with 0.3-meter resolution). However,
this increasing level of detail does not necessarily facilitate
building detection with an improved accuracy (Huang and
Zhang, 2011). Indeed, more detailed image contents actually
increase spectral ambiguities in remotely sensed images, such
as symbol patterns on the road, and big vehicles. Therefore,