International Archives of the Photogrammetry, Remote
Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
cauliflower. In addition, several pasture and clover fields and
small townships are scattered throughout the area.
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Study Area Bursa
Figure 1. Location of the study area, Karacabey, Turkey.
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Figure 2. A color composite of Landsat 7 ETM+ Bands 4, 5,
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and 3 (RGB) overlaid with the agricultural parcel boundaries.
Data Description
As remotely sensed imagery, Landsat 7 ETM+ data was
selected due its wider spectral coverage and availability of a
high resolution band (ETM Band 8) for enhancing spatial
resolution and features. Landsat 7 ETM+ data having Path: 180
and Row: 32 scenes were acquired on three dates: May 15, July
02, and August 19 2000. These scenes were found to be the
suitable dates for monitoring vegetation development in the
study area. From each scene, six visible infrared bands (Band 1-
5 & 7) having 30 m resolution and one panchromatic band
(Band 8) having 15 m resolution were used for the analyses. All
three scenes were cloud free and of good quality. Since full
scenes were not required for the achievement of this study, the
subsets of the images were extracted to match approximately
the same coverage with the vector parcel data (Figure 2).
The ground reference data for the study area were collected
through communicating with the farmers and making an
accurate land cover survey in mid August 2000. Particular
attention was paid to the selection of samples representative of
the extent and distribution of the land cover categories in the
study area. For each agricultural parcel, the current crop
situation together with the previous crop grown (where valid)
was recorded on the reference land cover map. Final ground
reference data of the study was generated through combining
information collected from farmers and the land cover survey in
the field. The reference data were subsequently used for
training and validating the classified outputs. In addition, the
knowledge obtained about the relationships between the
agricultural land cover classes and the agricultural parcel
boundaries were utilized (i.e. sugar beet restricted zones) to
improve classification accuracy.
The cadastral maps of the study area were obtained as hard
copy form from the cadastral office of Mustafa Kemal Pasa.
The area covered by eleven 1:5,000-scale and one 1 :7,500-scale
cadastral maps.
ANALYSIS
Preliminary Data Processing
The preliminary data processing steps consist of digitizing
agricultural parcel boundaries from 1:5,000 to 1:7,500-scale
map sheets and relating the attribute data to existing database:
and geometric correction following data fusion of the satellite
images.
Preparation of Vector Parcel Data: The cadastral maps were
subsequently scanned and registered using available control
points on the maps. The control points collected in a national
datum were georefenced to UTM (Zone 35) projection using
nearest neighbor resampling method. The maximum produced
RMSE value of 3.60 m was found to be quite satisfactory, since
it was less than a half pixel size of Landsat 7 ETM- imagery.
Next, each raster map was digitized using a polygonal topology.
When digitizing of raster maps were completed, edge matching
was performed to obtain a continuous data layer of agricultural
parcels (Figure 2). Together with agricultural parcel boundaries,
the supplementary data that came from the cadastral map and
the site visit were stored in a geographical information system.
The database held parcel information in conjunction with the
available land cover information in each parcel for further
analyses.
Data fusion: For each subscene, 30-m resolution Landsat 7
ETM+ multispectral bands 1 to 5 and 7 were fused with the 15
m resolution panchromatic band. The resulting fused bands
were spatially enhanced while keeping the spectral
characteristics close to the original multispectral bands. The
algorithm used has been developed by Atlantic Aerospace. Its
based on local correlation of edges to improve edges in loe
resolution bands wherever a corresponding edge is found in the
panchromatic band (Cheng et al., 2000). This is unlike the
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