Reference : Urban use of VHR images on Bukavu (Democratic Republic of Congo)
Scientific congresses and symposiums : Paper published in a book
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
http://hdl.handle.net/2268/3791
Urban use of VHR images on Bukavu (Democratic Republic of Congo)
English
Binard, Marc mailto [Université de Liège - ULiège > Département de géographie > Labo Surfaces >]
De Man, J. [ > > ]
Séba, G. [ > > ]
Vansteenvoort, M. [ > > ]
Gamanya, R. [ > > ]
Cornet, Yves mailto [Université de Liège - ULiège > Département de géographie > Cartographie et systèmes d'information géographique >]
Goossens, R. [ > > ]
Donnay, Jean-Paul mailto [Université de Liège - ULiège > Département de géographie > Cartographie et systèmes d'information géographique >]
De Maeyer, Ph. [ > > ]
2003
Proceedings of the Second Workshop of the EARSeL Special Interest Group on Remote Sensing for Developing Countries, Bonn, Germany September 18-20, 2002. EARSeL: Paris, France.
EARSeL
34-41
Yes
No
International
2-908885-55-7
Paris
France
Second Workshop of the EARSeL Special Interest Group on Remote Sensing for Developing Countries
du 18 septembre au 20 septembre 2002
EARSeL
Bonn
Allemagne
[en] The main purpose of this study was to show potential uses of very high resolution (VHR) image in
an urban analysis of Bukavu in the Democratic Republic of Congo. As for many of the Third-World
cities, Bukavu grew up during the last decades and available topographical information on Bukavu
dates back to the middle of the twentieth century. This lack of updated information can be compensated
by an appropriate use of VHR images. In this study, IKONOS image recorded on the 14th February
2001 was used.
Image registration are highly dependant on accurate Digital Elevation Models (DEM), these last
ones are also useful in urban analyses. The range between the minimum and maximum altitudes
observed in the image was more than 500 meters. Furthermore, the viewing inclination angle is more
than 28 degrees. In this case, orthorectification is mandatory for correcting relief displacements.
Nevertheless, the lack of good Ground Control Points (GPS’s) on the old topographic maps and the
failure to collect field verification data in Bukavu explains the remaining global 2D RMSE of
10 meters.
For easier image interpretation, multispectral (4m) and panchromatic (1m) images were fused
together by means of the LMVM algorithm. Depending on the object, the Computer Aided Photo
Interpretation (CAPI) uses or does not use the near infrared information (true or false colour
composite). For a more detailed interpretation about the city morphology we draped the 1m
multispectral fused image over the 1m resolution DEM grid.
The Built-up Area Index (BAI) computed on the urban mask obtained by CAPI and classification of
the vegetation, was compared with the 1954 situation interpreted from topographic maps. The present
city shows higher BAI values and in the same time the centre of the city has clearly shifted southward.
Statistical analyses are also done on built-up versus slope data.
The lack of good GCP’s and the use of DEM produced inaccurate orthorectification which was not
adequate for topographical features extraction. Nevertheless the present extensions of Bukavu built-up
areas are more than the double of those observed at the beginning of the last half century. New
constructions are located on steeper slopes where landslides are frequents. More features could be
extracted from the Ikonos image if good GPS measurements were made and if verification by the city
authorities was possible. Some practical applications of this study could involve determining better
location of new Bukavu extensions.
Researchers
http://hdl.handle.net/2268/3791

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