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IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India, 2002 
The texture has typically been a qualitative measure, it can be 
enhanced using mathematical algorithms. Feature extraction was 
attempted using texture analysis algorithms. For this, a subset of 
the chlorophyll image was selected to apply different types of 
texture analysis algorithms. Three texture analysis algorithms i.e. 
mean euclidean distance (1* order), variance (2" order) and 
skewness (3 order) were used for extraction of oceanic features. 
These algorithms are shown below, 
S [Xe -xijy]^ 
(1). Mean Euclidean distance: -—-—-————7——--— ----- (1) 
n-1 
Y(xuij -M)? 
(2), Variance z . e Late (2) 
n—l 
Z(xij - M”) 
(5) SRewness = + || | m (3) 
(n-1) (V^ 
Where, xij = DN value of pixel ij 
xc = DN value of a windows central pixel 
n = number of pixel in in the window 
M = mean of moving window 
»xij 
mean = ------- 
n 
V = variance 
3. RESULTS AND DISCUSSION 
Surface profile allows us to visualize in three dimensions the 
concentration/reflection spectrum of rectangular area of data file 
values an image. Spatial profile allows us to visualize the 
concentration/reflectance spectrum of poly line of data file values 
in an image. Surface profile gives an idea of structural patterns of 
the features as well as the morphology. Spatial profile helps in 
understanding the pattern of increase/decrease in concentration of 
chlorophyll concentration within the given feature spatially. 
Figure 1 indicates important features for exploring fishery 
resources (Solanki et. al. 2001b). 
3.1 Patterns of different features 
The patterns surface and spatial profiles of oceanic features have 
been shown in figure 2. The description of each feature types, its 
importance for fisheries and the profiles interpretation have been 
discussed here. 
Rings: Rings are derivatives of meanders and eddy. It can be easy 
to identify on an image as a circle shape. Rings are productive and 
already localized developed eco-system. These features ensure the 
secondary and tertiary production. The rings are in the circular 
fashion observed with higher chlorophyll concentrations in the 
periphery and low concentration in the center in surface profile. 
There is sharp increase in concentration and decline in 
465 
  
Figure 1: Oceanic features utilised to study the patterns 
concentration in the areas of center is clearly seen in spatial 
profile. This type of features can be easily identified through 
surface profile as well as spatial profile. 
Eddies: The current of water often on the side of main current, 
especially one moving in circle. Easy to monitor in space and 
time using remotely sensed data. Rotating water masses causes 
deep mixing and hence nutrient enrichment occured leading high 
production. Persistence is relatively longer duration. The visual 
predators like tunas prefer periphery of eddies and steamer. 
Circulating features with high chlorophyll concentration is clearly 
seen in surface profile. The increasing chlorophyll concentration 
with circulating pattern is seen in three dimension plots. The 
appearance of eddy is clearly observed in the surface profile. 
Similarly the picks and declines observed in spatial profiles. 
Fronts: Fronts are the boundary between the two water masses 
with different property. It can be easily detected as breaks ocean 
colour (chlorophyll concentration). High chlorophyll is an 
indicator of bio-mass production. Hence, resource sustained for 
longer period. The chances of development of local eco-system 
are more, which enables benthos exploration. The front indicates 
the gradient of chlorophyll concentration. There is abrupt 
increasing pattern in concentration is observed in surface profile. 
Similarly abrupt increase in concentration is seen in spatial profile 
as distance increases. 
Meander: Meandering pattern is turn or windings of the current 
that may be detached form the main stream. Easily detected 
through curvatures in the images. This enables large area extends 
in relatively smaller area. So that even if feature shift potential 
area may not shift totally. This also helps in delayed fishing. In 
the smaller area large amount of phytoplankton concentration is 
available as compared to linear feature. It forms enclosed pocket, 
hence confine the resources. Some time it terns into rings, which