Analysis of ALOS PALSAR and TerraSAR-X Data for Protected Area
Mapping: A case of the Bwindi Impenetrable National Park-Uganda
J.R Otukei
a, b
T. Blaschke
b
, M. Collins
c
, Y. Maghsoudi
c
a
Department of Geomatics and Land Management, Makerere University, P.O. Box 7062 Kampala Uganda
b
Centre for GeoInformatics, University of Salzburg, Hellbrunerstrasse 34, 5020 Salzburg Austria
c
Department of Geomatics Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada
Abstract-The main purpose of this study was to
investigate the potential of Quad-pol L-band ALOS
PALSAR and Dual-pol X-band TerraSAR (TSX) data,
as well as derived TSX image texture for land cover
mapping. A per- pixel classification was performed
using non-parametric decision tree method.
Classifications involving the HH, VV and HH/VV
TSX polarimetric band(s) resulted in kappa indices of
0.4326, 0.3577 and 0.4657 respectively. In contrast,
classifications involving the HH, HV, VV, HH/HV,
VV/HV, HH/VV, HH/HV/VV and HH/HV/VH/VV
bands of ALOS PALSAR data resulted in
corresponding kappa indices of 0.2972, 0.3395,
0.3269, 0.7141, 0.7058, 0.4697, 0.7311 and 0.7177. A
further analysis was carried out using the image
textures derived from the HH polarisation of TSX data.
Three different categories of textures were analysed:
SAR specific (SARTEX), textures based on grey level
concurrence matrices (GLCM) and textures based on
SAR image histogram (HISTEX). These resulted in
kappa indices of 0.6740, 0.6655 and 0.7166
respectively. Moreover, a classification using two
original TSX polarisations provided a kappa index of
0.4657. This showed an improvement in the
classification accuracies by 45%, 43% and 52%
respectively. On the basis of the resulting accuracies, it
can be concluded that analysis of data with high
polarisation increases the classification accuracy of
land cover information derived from SAR data.
Furthermore, inclusion of derived SAR textures in the
classification process, provide a potential for improved
land cover identification and mapping in the tropics.
1 Introduction
The Bwindi Impenetrable National Park (BINP)
is facing pressure due to demand for arable land and
habitat resources [1]. While the land cover within the
protected core zone is still undisturbed, the surrounding
areas, originally gazetted as forest reserves, have been
completely cleared for cultivation. The conversion of
tropical forests in areas such as the BINP into other
land cover types has severe long term environmental
and social economic consequences both locally and
globally [2].
In order to mitigate the effects of global warming
as well as protect the wide range of biodiversity, there
is need to conserve the forests cover. This can be
supported through accurate and up-to-date land cover
information. However, the production of accurate and
up-to-date thematic land cover maps in the tropical
environments is hindered by many factors including
the high costs and cloud cover [3]. Data from Synthetic
Aperture Radar (SAR) systems are envisaged to play a
key role for mapping and monitoring of protected
areas, especially in tropical areas with persistent cloud
cover [4-7]. This is due to the ability to acquire data
348 978-1-4577-1005-6/11/$26.00 ©2011 IEEE IGARSS 2011