| dc.description.abstract | Coral reefs are an important
coastal eco-system in Sri Lanka. Current
study was conducted on Vankalai area
regarding to develop new method of remote
sensing technique to mapping and
monitoring the particular coral reef ecosystem. Downloaded Landsat 8 satellite
images were processed under the three
headings which are preprocessing,
processing and post processing. Image
preprocessing is used to eliminate errors in
satellite images. Depending upon the source
of error, inadequacy revision and
imperfection expulsion are separated into
two types such as radiometric correction and
geometric correction. In radiometric
correction the foremost requirement is to
conversion of DN values to spectral radiance
values. And the next step is conversion of
radiance values to Top of Atmospheric (TOA)
reflectance which could be identify as a unit
less ratio measurement. Normalized
difference water index was used to enhance
water features and suppress the land area.
Different types of bottom substrates were
identified using Depth invariant index (DII)
for study area and which are classified
according to the bottom substrate using
unsupervised classification. Five types of
different spectral classes were identified
using developed method which are coral
reef, rough bottom, vegetation cover, sandy
bottom and deep muddy area. These spectral
classes are related to elevation of benthic
habitat. Ultimately map was generated with
regarding to the bottom substrate for
particular study area using Landsat 8 image.
It is an extensive reef area but lack of details
yet. This study is the first attempt to use
Landsat 8 for coral reef mapping in Sri Lanka. | en_US |
