taluk level using satellite remote sensing data base on sound
statistical and image processing techniques.
METHODOLOGY
The study area consisted of a cluster of six villages, viz., Melur,
Mallur, Muttur, Kachahalli, Ganganahalli and
Patalammanahalli, under Melur TSC, Sidlaghatta taluk. The
total geographical area is about 11.22 sq. km.
Data Used:
Satellite data:
The IRS-1C-LISS-IH and PAN digital data of path 100 row 64
acquired in 3 different dates of LISS-III data (in 24 days
intervals) has been employed, starting from 03.03.1997 to
20.04.1997, for mulberry garden condition assessment .
Ancillary data:
Survey of India topographical maps on 1 : 50,000 scale were
used along with village / cadastral maps obtained from the
Department of Survey, Settlement and Land records, GOK.
Ground truth data:
“ The ground truth data collection has an important bearing on
most of the remote sensing applications. The phonological
observations on mulberry crop such as growth stage, vigor,
ground cover percent, soil type, etc., were collected in detail on
survey number wise ( Medhavy, et al., 1993; Dutta, et al., 1992
) Ground truth data collection in all the six villages, survey
number wise was synchronised with the satellite passes.
Digital analysis:
The digital data analysis was carried out at RRSSC, Bangalore
on IBM RISC 6000 system using EASI / PACE software and
“CAPE MANAGER’ software developed by RRSSC, Nagpur
and SAC, Ahmedabad. The methodology followed in the
present study is described briefly below (Anonymous, 1990b;
Bauer, 1985). :
Extraction of data:
The administrative boundary of Sidlaghatta taluk was digitised.
A merged product is generated using IRS-1C-LISS-III and
PAN digital data. Initially, georeferencing of the satellite data,
which was carried out for acreage estimation has taken as
georeferencing of the satellite data covering an area of a cluster
of six villages of Sidlaghatta taluk. For image-to-map
rectification a total of 12 GCPs were located in the image with
reference to 1 : 50,000 scale toposheet. Since the image size
was small, first order polynomial geometric transformation was
found quite adequate between map-to-image co-ordinates of
GCPs. The accuracy achieved through this simple linear
transformation was at subpixel level in both X and Y
direction. Sub-images covering a cluster of six villages were
also extracted from data of remaining two dates. Then image to
image registration was done with respect to the rectified master
image ( Anonymous, 1986; Geeta Vardhan, et al, 1992 ).
Radiometric resampling of pixels using nearest neighbor
techniques was applied as this enables pixel by pixel
comparison of multi-temporal change during the growth cycle.
The image of multi-temporal data of part of Sidlaghatta taluk
was generated. It consists of three dates with four bands each
was extracted separately and stored for further analysis. The
LISS-III data was digitally resampled and registered with edge
enhanced PAN data using image to image transformation
model. Hue Intensity Saturation (HIS) transformation was used
to merge the information contents of both the data sets.
IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India, 2002
Cadastral map was overlayed on merged data on
approximately 1 : 12,500 scale. The methodology comprises
satellite data processing, generation of raster cadastral images,
registration of cadastral images, generation and overlay of
cadastral vectors over the digitally classified images. These
hybrid images depict field boundaries, cart tracks, small nullahs
besides the settlements, tanks and other cultural features like
roads and canals. Most of the survey / parcel boundaries on the
cadastral maps match well with these features. This is an
advantage in identifying GCPs for developing transformation
model for image to image tie down ( Geeta Vardhan, et al.,
1992 ).
Generation of raster cadastral images:
The cadastral map was scanned and corresponding raster
images were generated. The thickness of parcel boundaries
were thinned using the Kernel based software.
Registration of cadastral images:
The cadastral images were registered with high resolution edge
enhanced colour composite using large number of GCPs. An
accuracy of less than half a pixel of standard and residual errors
were achieved while registration of cadastral images. Due to the
resampling of the radiometric values the parcel boundaries were
found to discontinuous lines and to avoid the problems of
artifacts and null points, a special software developed at the
RRSSC, Bangalore was used for the cadastral maps
registration. The resultant output depicts continuous lines of
the parcel boundaries ( Rao et al., 1996 ).
Generation and overlay of cadastral vectors:
The registered parcel boundaries were overlaid on satellite data
in the form of raster bit maps or vectors. Vectors overlay is
preferred to raster overlay because of its unique line thickness
consistent with the reduction / enlargement of the raster images
and optimal utilisation of the disk space. Vector boundaries
were generated either from conversion of raster image or by
digitisation of raster boundaries ( Radhakrishna, et al., 1996 ).
Mulberry crop condition assessment procedure:
The study area is extracted using the mask, covering six
villages, for digital analysis of three dates and subjected to
further processing to derive information on mulberry growth
conditions. Flow diagram illustrating the methodology for crop
condition assessment is shown in Fig. 3H.
Generation of vegetation index:
Vegetation Index is a ratio based on reflectance in the Red and
NIR bands of the electromagnetic spectrum. Vegetation Index
(VI) images were derived from empirical transformations of
spectral responses in different spectral bands. Normalised
Difference Vegetation Index (NDVI) used for monitoring the
growth conditions of mulberry in the present study was
generated by using the equation given below:
NDVI=IR-R/IR+R
Where, IR - reflectance in the infrared band ; R - reflectance in
the visible red band and NDVI - normalised difference
vegetation index. The NDVI images were generated for all the
three satellite data sets.
Generation of crop growth profile:
Digital data of IRS -1C-LISS-III of 3 dates in a crop season
were used to generate mulberry crop growth profile. The 20th
April, 1997 image registration was done with respect to the
rectified master image.
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