Two image processing experiments are described using a MSS-LANDSAT scene from the Tres Marias region and a shuttle Imaging Radar SIR-A image digitized by a vidicon scanner. In the first experiment the study area is analyzed using the original and preprocessed SIR-A image data. The following thematic classes are obtained: (1) water, (2) dense savanna vegetation, (3) sparse savanna vegetation, (4) reforestation areas and (5) bare soil areas. In the second experiment, the SIR-A image was registered together with MSS-LANDSAT bands five, six, and seven. The same five classes mentioned above are obtained. These results are compared with those obtained using solely MSS-LANDSAT data. The spatial information as well as coregistered SIR-A and MSS-LANDSAT data can increase the separability between classes, as compared to the use of raw SIR-A data solely

Dutra, L. V.

Kux, H. J. H.

Parada, N. D. J.

English

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n r! (E84-10148) EVALUATION OF SIR-A (SHUTTLE	 N84-26096IMAGING RADAR) IMA IGES FROM THE TRES MARIASREGION (MINAS GERAIS STRTE, BRAZIL) USING
DL•'RIVED SPATIAL FEATURE'S AND REGISTRATION	 nliclas
61TH (instituto de Pesquisas Espaciais, Sao G3/43 00148
•	 SECRETARIA DE PLANEJAMENTO DA PRESIDENCIA DA REPUBLICA
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTIFICO E TECNOLOGICO
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1.	 Publication N4 2.	 Version 3.	 Date 5.	 Distribution
INPE-3113-PP,E1510 May,	 1984 q Internal (3 External
q Restricted4.	 Origin	 Program
DSR	 COMEA
6.	 Key words - selected by the author(s)
SIR-AIAISS-LANDSAT	 FILTERING TECHNIQUES
IMAGE PROCESSING	 COREGISTRATION
THEMATIC CLASSIFICATION
7.	 U.D.C.:
	 528.711.7:621.376.5
8. Title
	
INPE-3113-PRE1510 10.	 No of pages:
	
07
EVALUATION OF SIR-A (SHUTTLE IMAGING RADAR)
IMAGES FROM THE TRES MARIAS REGION (MINAS 11.	 Last page:	 06
GERAIS STATE, BRAZIL) USING DERIVED
12.	 Revised bySPATIAL FEAT URc S AND Rt, Gi STRATION
WITH MSS-LANDSAT IMAGES
I(t^'/63 Z ^)«^^`9. Authorship	 Hermann J. H. Xux
Luciano Vieira Dutra
Nelson D'Avila Mascarenha
13.	 Authorized by
Responsible author
	
^^ti-fn^X Nelson de Jesus	 r	 a	  Pa^ad^i „	 -
 
General
14.	 Abstract/Notes
Two image processing experiments were described using a MSS-
LANDSAT scene from the Tres Marias region and a SIR-A image digitized by a
vidicon scanner. In the first experiment the study area was analyzed using
the original and preprocessed (filtering techniques) SIR-A image data. The
following thematic classes were obtained: water, dense savanna vegetation
("cerradao"), sparse savanna vegetation ("cerrado"), reforestation areas and
bare soil areas. In the second experiment, the SIR-A image was registered
together with MSS-LANDSAT bands 5, 6 and 7. The same 5 classes mentioned
above were obtained. These results were compared with those obtained using
solely b1SS-LANDSAT data. As a conclusion it can be stated that the spatial
information as well as coregistered SIR-A and MSS-LANDSAT data can increase
the separability between classes, as compared to the use of raw SIR-A data
solely.
15.	 Remarks	 presented at the International Societ:j for Photogrammetry and
Remote Sensing Congr. ss, Rio de Janeiro, June 18-29, 1984.
R
i
0.1
EVALUATION OF SIR-A (SHUTTLE IMAGING RADAR) IMAGES FROM THE
TRES MARIAS REGION (MINAS GERAIS STATE, BRAZIL) USING DERIVED
SPATIAL. FEATURES AND REGISTRATION WITH MSS-LANDSAT IMAGES
Hermann J. H. Kux and Luciano Vieira Dutra
CNPq - Instituto de Pesquisas Espaciais - INPE
C. P. 515 - 12200 - Sao Jose dos Campos - SP - Brazil
Commission VII
ABSTRACT
Two image processing experiments were described using a MSS-LANDSAT
scene from the Tres Marias region and a SIR-A image digitized by a vidicon
scanner. In the first experiment the study area was analyzed using the
original and preprocessed (filtering techniques) SIR-A image data. The
following thematic classes were obtained: water, dense savanna vegetation
("cerradao"), sparse savanna vegetation ("cerrado"), reforestation areas
and bare soil areas. In the second experiment, the SIR-A image was
registered together with MSS-LANDSAT bands 5, 6 and 7. The same 5 classes
mentioned above were obtained. These results were compared with those
obtained using solely MSS-LANDSAT data. As a conclusion it can be stated
that the spatial information as well as coregistered SIR-A and FSS-LANDSAT
data can increase the separability between classes, as compared to the use
of raw SIR-A data solely.
1. INTRODUCTION
The Shuttle Imaging Radar (SIR-A), flown on board the Space Shuttle
during November 1981,.was the first orbital imaging radar to take images
over the Brazilian territory.
Considering that the SIR-A data available was not on a digital form, it
had to be digitized to be compared with 'ISS-LANDSAT data. Within this
context, the objective of this stuoy is the comparison between SIR-A images
and MSS-LANDSAT images for land cover/land use studies, using image
processing systems.
2. BRIEF DESCRIPTION OF THE STUDY AREA
^.
	
	
The area under study (Figure 1) consists mainly of sedimentary
formations (Pre-Cambrian age) including siltstones, arkoses, claystones,
sandstones, slates, marls and limestones. According to Menezes et al.(1977)
extensive Cainozoic reworked sedimentary cover as well as alluvial and
recent floodplain deposits occur within this region.
1	 After Panoso et al. (1978) the following soil types predominate in the
1-
	
	
study area: dark-red distrophic latosols, distrophic ca-nhisols and litolic
soils associated with different lithologies, relief forms and vegetation
types.
The digital classification of a MSS-LANDSAT scene (date: August 27,
1978) allowed the obtainment of 4 main classes of land cover/land use which
will be succintly described below:
1. Cerradao (also known as ScIerophyllous woodland after Bourl i e`re , 1983)
!	
is commonly composed o f up to 3 different strati, namely:
i
nORIGINAL PAGE 19
OF POOR QUALITY
1. short grass and forbs stratum;
2. shrubs and low trees stratum;
3. a tree stratum 5-6 m high with curved trunks mostly hardwood.
MINAS GERAIS STATE
41°W
115°S
49°W i
I	 /
^oLI S 49°W 21°S
A
F
41°W
0	 200Km
Fig. 1 - Localization of the study area.
Within the study area, "cerradao" occurs most conspicuously on the
southern part of the Tres Marias hydroelectrical power plant, over gently
rolling terrain. According to Panoso et al., dark red distrophic latosols
with clay texture are the predominant soil type in this section.
2. Cerrado
"Cerrados" constitute, within the study area, an extensive savanna
vegetal formation, intensively changed due to clear cuts and grass
burnings. Four main physiognomic savanna types can be identified in
the field: savanna grassland ("campo limpo"), tree and/or shrub
savanna ("campo sujo"), wooded savanna ("campo cerrado") and savanna
woodland ("cerrado"). Cerrados occur most frequently on very hilly
terrain over litolic soils and associations of litolic soils with
distrophic cambisoils.
O'
3. Bare soil areas
These areas which were formerly defo rested and burnt down, are
located predominantly over scarped hills and litolic soils. Due to
its intensive use as pastureland or for charcoal obtainment
activities, the vegetation cover of this area is almost inexistent,
originating soil erosion processes.
4. Reforestation areas
Reforestation areas constitute small sections, normally located over
deep soils. Within the area under study, the reforestation is made
essentially with Eucalvotus. This has caused serious problems of
soil nutrients exhaustion.
For further information on the area under study, see Sausen (1981)
who made a comprehensive study on correlations between relief,
geology, soils, vegetation and drainage from the upper Rio Sao
Francisco basin, including the Tres Marias region, using MSS-LANDSAT.
I3. METHODOLOGY
l
The problems concerning digital classification normally involve
mult ispectral images. As for SIR-A, there is originally just one channel
which includes spectral as well as spatial information. The latter one may
1
	
	
be extracted to help on the class discrimination procedures. Besides that,
additional information from other sources can be added to this channel;
e.g. LANDSAT-MSS: several MSS channels can be coregistered with SIR-A data.
This study is constituted by 2 experiments on processing of digital
data using a SIR-A image digitized by a vidicon scanner (General Electric),
coupled to the imaging system IMAGE-100 from INPE. At the first experiment
3 channels were used with the following arrangement: on the first channel
the digitized SIR-A data were stored; the second was the original SIR-A
channel processed by a low-pass filter to extract the information related
to the clustering characteristics of thematic classes (Dutra & Mascarenhas,
1984). The third finally consists of the first channel processed by a high-
pass filter to enhance the information on relief roughness. The low-pass
filter used, developed by Dutra & flascarenhas (1984), is graphically
represented on Figure 2. This filter corresponds to an average in a region
of 5 by 5 pixels.
01110
	
1	 11111
11111
	
21	 11111
_01110_
Fig. 2 - Low-pass filter.
I,	 To extract roughness information a heuristic filter called "variation"r
(after Schachter et al., 1979) was used. Consid`ring a neighborhood of 3 by
li p^	 3 around a pixel and labeling the pixels of this neighborhood by
r a b c
d x e
f g h
,e 
I
I	 A
I	 A
we get that the total variation (TV) is the sum of vertical variation (VV)
and horizontal variation (HV), namely:
VV = la-di + Jb-xJ + Ic-el + Jd-fl + Jx-gJ + Je-hJ
HV = (a-bl + Jd-xJ + (f-gl + lb-cl + Ix-el + Jg-hJ
TV = VV + HV
I
The digital filtering is a procedure to extract the spatial attributes
since the content of spatial frequency expresses, in a certain way, the
spatial relationship between the pixels (Dutra & Mascarenhas, 1984). The
combination of the 3 channels created at the first experiment allowed a
digital classification, using a maximum likelihood algorithm developed by
Velasco et al. (1978). Five thematic classes ("cerrado", "cerradaao",
exposed soil, reforestment and water) were obtained. Besides that, the
classification matrices of the test-sites and training areas were obtained,
which are analyzed on item 4 of this study.
At the second experiment the original SIR-A channel (first channel of
the first experiment) was coregistered to MSS-LANDSAT channels 5, 6 and 7,
using an affine transformation (first grade polynomial). The same 5 classes
mentioned above were obtained using the same classifier.
4. DISCUSSIONS OF RESULTS
i
	
	
The values of average performance (AP), average confusion (AC) and
average rejection (AR) are listed on Tables 1 and 2. They are related to
training and test areas referring to the SIR-A data used at the first
experiment'.
TABLE 1
I
EVALUATION OF TRAINING AREAS, FIRST EXPERIMENT
ORIGINAL SIR-A 3 SIR-A	 (*)
CHANNEL CHANNELS
THRESHOLD 5 6 5 6
AP (%) 79,3 79,3 85,3 85,6
AR 0,0 0,0 1,1 0,3
AC 20,7 20,7 13,6 14,1
^- (*) The 3 channels considered are: 1) original
SIR-A channel; 2) VARIHV S with MD5FIL 2
B = C = 1 (low pass filter); 3) MD5FIL 2
B = C = 1 (high pass filter).
fil
in
Average performance is defined as the average ercentage of correct
classification for each area (training or test , weighted by the number
of points in the area. Analogous definitions are valid for average
C	
confusion and average rejection, substituting correct classification by
classification error and rejection, respectively.
k
SIR-A AND MSS MSS CHANNELS
MERGED CHANNELS 4,	 5,	 6,	 7
THRESHOLD 5 6 5 6
AP	 (%) 87,6 90,5 91,3 92,2
AR 4,6 0,2 1,2 0,3
AC 7,8 9,3 1,5 7,5
- T7.
TABLE 2
EVALUATION OF TEST AREAS, FIRST EXPERIMENT
ORIGINAL SIR-A	 3 SIR-A
CHANNEL
	
CHANNELS
THRESHOLD	 5	 6	 5	 6
AP (%)	 72,3	 72,3	 76,9	 77,2
AR	 0,0	 0,0	 2,2	 0,5
AC	 27,7	 27,7	 20,9	 22,3
The relatively high AP values for both training and test areas
demonstrate the usefulness of SIR-A data for digital classification
purposes. Furthermore it is noted that the use of spatial information (the
use of low-pass and high-pass filters) improve the classification results.
At the second experiment (see Tables 3 and 4) the main interest was to
analyze the possibilities of merging and conjunct use of SIR-A and MSS-
LANDSAT data.
TABLE 3
EVALUATION OF TRAINING AREAS, SECOND EXPERIMENT
A	 B
SIR-A AND MSS MSS CHANNELS
MERGED CHANNELS 4,	 5,	 6,	 7
THRESHOLD 5 6 5 6
AP W 95,2 95,7 91,0 91,8
AR 0,7 0,3 1,1 0,3
AC 4,1 4,0 7,9 7,9
TABLE 4
EVALUATION OF TEST AREAS, SECOND EXPERIMENT
A
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E
F
r
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imparing the 4 tables one can observe that a conjunct use of SIR-A and
mZ)Z^-LNNDSAT data improved the average performance at train,ng areas.
On the other hand, the average of test areas (Table 4A) is lower if
compared to the exclusive use of MSS (Table 3B and 4B) data. Apparently
this lower performance, as shown on Table 4A, is an indication of a problem
related to the extension of the spectral signature per class. This is
probably related to factors which changed the spectral response of the radar
return signals for the same class. Additionally, the scanner process used
to convert the radar image to digital form can induce degradations due to
spatial nonlinearities of the scanner equipment.
Besides that, eventually residuals of the geometric correction
procedures used have contributed to confound the considered classes.
We believe that a more detailed study on the applicability of SIR-A
data to the land cover classes used, will provide further information to
optimize digital classifications of this orbital imaging radar. Within this
context, the use of the technique of feature selection to choose the 4 most
informative channels, seems to be recommended as it was demonstrated in
some preliminary inedited experiments.
REFERENCES
Bourliere, F. (editor) Ecosystems of the world, vol. 13: Tropical Savannas
Amsterdam Elsevier Scient. Publ. Co., 1983.
Dutra, L.V. & Mascarenhas, N.D.A. Some experiments with spatial feature
extraction methods in multispectral classification. Internat. Journal
of Rem. Sensing, 1984, vol. 5(2):303-313.
Menezes Filho, N.R. de; Mattos, G.M.M. & Ferrari, P.G. Projeto Tres Marias.
Relat6rio Final. Belo Horizonte, DNPM, 1977, vol. 1, 399 p.
Panoso, L.A.; Santana, D.P.; Baruqui, A.M.; Baruqui, F.M.: Almeida, J.R.de;
Ferreira, M.B.; Souza, C.C. de & Antunes, F.Z. Levantamento de reconhe
cimento detalhado dos solos da area sob a influencia do Reservat6rio de
Tres Marias. Salo Horizonte, EPAMIG, 1978. 	 (Bol. Tecnico SNLCS, 57).
Sausen, T.M. Estudo da dinamica do Alto Rio Sa` o Francisco e reservato-rio
de Tres Marias, atraves de imagens MSS-LANDSAT. M.Sc.-Thesis, Sao Jose
dos Campos, INPE-2249-TDL/066, 1981, 272 p.
Schachter, B.F.; Davis, L.S. & Rosenfeld, D.A. Some experiments in image
segmentation by clustering of local features values. Pattern
Recognition, 11:19-28, 1979.
Velasco, F.D.R.; Prado, L.O.C. R Souza, R.C.M. Sistema MAXVER: manual do
usuario. Sao Jose dos Campos, INPE, julho 1978.	 (INPE-1315-NTI/110).
Im
r


Evaluation of SIR-A (Shuttle Imaging Radar) images from the Tres Marias region (Minas Gerais State, Brazil) using derived spatial features and registration with MSS-LANDSAT images

Evaluation of SIR-A (Shuttle Imaging Radar) images from the Tres Marias region (Minas Gerais State, Brazil) using derived spatial features and registration with MSS-LANDSAT images

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