International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B1. Istanbul 2004
evaluation by SCOT on Toulouse area, France (Galaup, M., and
Dupuy, S., 2003) with a slightly different approach.
An automatic method was developed, taking full advantage of
urban objects responses and spatial distribution. Processing
steps have been conducted with eCognition, commercial
software which follows an object-oriented concept and where it
is possible to define rules between objects. This region-based
method produces results more detailed than pixel-based
classification used on Barcelona, but requires a very deep
expertise both in e-Cognition utilisation and logical rules to be
applied.
SPOT S's improved resolution and spectral sensing capability
make it possible to elaborate thematic information layers using
automatic image processing methods, consistent with the needs
of urban planners.
3.1.4 Urban monitoring for population census
The results of GeoTerralmage investigation show that SPOT 5
has an advantage for census applications compared to lower
resolutions, especially when attempting to classify or quantify
urban change (Ferreira, F., 2004).
Imagery was evaluated in the three following applications :
urban change detection, urban structural classification and
detail of imagery to allow counts of buildings.
Allthe mapping is based on visual interpretation and heads up
digitizing of urban changes. Visual interpretation uses the
human eye and brain to consider context, shape, proximity and
texture to identify features on satellite imagery.
The classification of the change area according to the urban
structural classes showed that medium resolution sensors such
as Landsat are not adequate for this procedure. Although some
structures could be recognised and identified from Landsat, it is
not possible to classify all structures. SPOT 5 Colour (10m) and
B&W (5m) could classify all the classes except the low cost
housing, which is a class of dense, but very small houses. The
SPOT 5 merge of Colour (10m) and B&W (5m), Colour (10m)
merge with B&W (2.5m), and B&W (2,5m) could clearly
classify all classes.
The final stage to perform building counts in order to quantify
urban growth indicated that only SPOT Colour (10m) merged
with B&W (2.5m) and B&W (2,5m) could distinguish buildings
in all structural classes with confidence.
It is now possible to use only one set of imagery to perform
three procedures, while. previously it required two or three data
sets and the same amount of workflow procedures. The
subsequent reduction manpower and costs required for
processing and mapping, creates strong advantages for Statistics
South Africa. The possibility to acquire data on a closer date of
acquisition to census date through programming services, and
the uniform image coverage for areas where population are
concentrated, are also strong assets for SPOT 5 imagery.
3.2 Natural disasters management
The investigation conducted by UNOSAT was made in close
collaboration with the Laboratoire de Géologie de l'Ingénieur et
de l'Environnement (GEOLEP) of the Swiss Federal Institute of
Technology (EPFL) (Retiére, A., Senegas, O., Parriaux, A.,
Haeberlin, Y., and Turberg, P., 2004). It aimed at testing the
suitability and potential of SPOT-5 data in combination with
digital elevation models (DEMs), topographic maps and a
geological GIS database for the generation of vulnerability
maps related to landslides, mud flows and debris flows in the
Matagalpa area, Nicaragua.
SPOT 5 imagery appeared to be an effective tool for the visual
evaluation of landslides and to a lesser extent mud and debris
flow. A false color 2.5 m SPOT-5 color image, best enhanced
with a DEM, allows to delimit hazard areas at a scales
consistent with the 1:25,000 scale up to the 1:10,000, and to
create a comprehensive inventory map. Some parameters, such
as the rate of vegetation disturbance might even yield a
qualitative monitoring of the activity. However, the recognition
depends to a great extent on the ability and experience of the
interpreter. This tool usefully complements traditional
surveying methods based on aerial photography.
For risk susceptibility maps (which sectors are potentially risk
areas for each natural hazard type), the integration of SPOT 5
products is less straightforward and needs to be combined with
the use of DEMS and classified slope maps.
Since 2000, many other successful rapid mapping services have
been provided through the International Charter "Space and
Major Disasters". SPOT 5 data were tested in particular during
the dramatic flash floods which severely affected the Southern
part of France in September 2002. (Yésou, H., Clandillon, S.,
Allenbach, B., Bestault, C., De Fraipont, P., Inlgalda, J.,
Favard, J.C., 2003).
Thanks to the constellation, 6 SPOT images, were acquired
between the 10th and 11th, plus on the 14th two SPOT 5 scenes
in multispectral, 10m, and 2.5m. Furthermore, two pairs of
SPOT 5 XS and 2.5m, 2002 summertime data, were taken as
reference data.
It is was shown that based on the SWIR channel it was possible
to monitor the soil water content decreasing over 5 days
allowing in fact to map the flash flood extent one or more days
after the event.
The SPOT-5 2.5 m natural colour product, was used as a
reference image, associated with the flood extent, generated
much interest within the rescue services because of their very
high detail and their updated information compared to existing
topographic maps, allowing to identify new built areas which
were affected by the floods.
Compared to former actions, this Charter action highlighted the
benefits of the SPOT 5 VHR as well as the SWIR channel and
also the SPOT constellation's potential as images from three
SPOT satellites were used for rapid damage mapping.
3.3 Agriculture and Forestry
3.3.1 Agriculture
In the frame of the European Union's MARS-PAC programme,
Spot Image has supplied SPOT products every year covering 60
sites in the 15 member states over the past 10 years.
Among the satellite data provided in the frame of the 2003
MARS PAC campaign, 430 SPOT (including 54 SPOT 5)
products were provided to the European Community, i.e. more
than 63% of the total number of products including radar and
VHR optical images. Thanks to this project, the EU obtains
every year a direct inventory of utilized agricultural areas and
main annual crops.
In the frame of the SAVP, JRC has led a study on the use of
SPOT 5 data to control area based agri-environmental
measures over “extensive fruit orchards” in Baden-
Württemberg test site, southern Germany (Baruth, B., Aastrand,
p.
satt
me
the
Thi
res
we
206
Th
dat
cle
ex
wh
cr
or
bli
ort
be
ins
se
stt
of
im
cy € 00 ^
un
