Recent Advances on 2D and 3D Change Detection in Urban Environments from Remote Sensing Data - Computational Approaches for Urban Environments - page 234

which were employed in recent change detection studies, is reported along with the
major data specifications and cost. Apart from their spatial, spectral, and temporal
resolution, their cost is referring to archive data (apart from the Cartosat-1 case)
and is associated with the specific product/mode which offers the highest spatial
resolution. The cost refers to list prices (e-geos 2013 ;GeoStore 2013 ) and has been
estimated for the minimum (“per scene”) order and per square kilometer (km 2 )in
order to ease the comparison. It is obvious that when moving from the medium-
and high-spatial-resolution products to the very high-resolution ones, the cost per
square kilometer increases significantly i.e. , from about 1 Cperkm 2

C.
The high-spatial-resolution SAR satellite sensors are, also, offering costly products,
similar with or higher than the optical ones. In addition, it should be noted that as
we are moving from smaller to larger spatial scales, the number of images required
to cover the same area increases significantly. Therefore, the cost for delivering
change detection geospatial products increases exponentially as we are moving from
regional land cover/use or urban growth studies to local building change detection
and cadastral map updating.
In Table 10.3 , recent change detection approaches are classified according to
the type of the remote sensing data used in each recent study. Medium- to high-
resolution optical data, radar data, and multimodal data (Fig. 10.1 ) are holding
the biggest share among the recent change detection research activity. However,
3D data (satellite or airborne) and vector data from existing geodatabases are
gaining increasing attention for spatiotemporal monitoring in local scales. In region
scales, the research activity, as has been already mentioned, has been empowered
from the increasing US and EU open data policies. Moreover, new open products
which include basic but necessary preprocessing procedures will boost more
research and development for quantifying global and regional transitions given
the changing state of global/regional climate, biodiversity, food, and other critical
environmental/ecosystem issues. Web-enabled Landsat data is an example, where
large volumes of preprocessed Landsat 7 Enhanced Thematic Mapper Plus data are
operationally offered for easing the mapping procedure of land-cover extent and
change (Hansen et al. 2014 ).

A to about 20 A

10.4 Data Preprocessing

Certain factors, such as the radiometric calibration and normalization between
multitemporal datasets, the quality of atmospheric corrections, the quality of data
registration, the complexity of the landscape and topography under investigation, the
analyst's skill and experience, and last but not least, the selected change detection
algorithm, are directly associated with quality of the change detection product. The
initial preprocessing stage, which current efforts try to standardize (Yang and Lo
2000 ; Chander et al. 2009 ;Hansenetal. 2014 ), addresses important issues regarding
the radiometric, atmospheric, and geometric corrections in the available datasets
transforming them from raw to geospatial ready-for-analysis data. However, there