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IOC/WESTPAC Workshop on
Remote Sensing for Coastal Habitat Mapping Busan, Korea, 30th – 31th March, 2011
Analysis of Coral Reef Spectral Respond on ALOS-AVNIR
Satellite Data in Pari Islet, Thousand Island District
Jakarta Indonesia
*Muhammad Helmi, *Munasik, *A. Hartoko and **S. Wouthuyzen
*Marine Sciences Department, Fac of Fisheries and Marine Sciences, Diponegoro Univ.
Jl. Prof. Sudharto, Tembalang, Semarang 50275, INDONESIA, Email; [email protected]
**Coastal and Marine Geomatic Center – FPIK, UNDIP, INDONESIA
***Senior Researcher of Center for Oceanological Research and Development
The Indonesian Institute of Science, Jakarta, INDONESIA
Backgound
Pari Islet (a group of small islands) in
Thousand Islands District has great variation
and complex coastal ecosystem, such as coral
reefs and seagrass, beach forest and
mangrove.
This rather large shallow and clear water islets
could be ideal for spectral- respond analysis of
satellite multispectral data.
Objective
To asses spectral respond of ALOS-AVNIR
multispectral image on coral reef ecosystem.
To study the Lyzenga, Hue Saturation
Intensity (HSI) and Principle Component
Analysis (PCA) transform for coral reef
features highlighting and mapping.
Research Area
Pari Islets, Thousand Island, North Jakarta
Jakarta
Pari Islets
Method
Spatial Data :
- ALOS-AVNIR , multispectral full band, 10m
resolution, April 30th 2008 (JAXA Japan)
- Topographic map 1:25.000 scale, Bakosurtanal
- Coastal Environmental Map (LPI) 1:50.000 scale,
Bakosurtanal
Multispectral Band of ALOS-AVNIR, April 30th 2008
Blue Channel Green Channel
Red Channel Near IR Channel
ALOS-AVNIR
Result and Analysis
Accuracy
Assessment
Topography
and LPI Map
Radiometric, Geometric
and Enhancement
Process
- HSI Transform
- PCA Image Transform
Water Column
Correction and Lyzenga
Transform
MethodFlow Chart
Coral Reef Mapping
Survey
PCA Transform PC1= SIGMA(I1..I4|I? * PC_COV(,R1,I?,1))
PC2= SIGMA(I1..I4|I? * PC_COV(,R1,I?,2))
PC3= SIGMA(I1..I4|I? * PC_COV(,R1,I?,3))
IF (MAX(i1,i2,i3) = MIN(i1,i2,i3))
THEN 0
ELSE
((IF (i1 = MAX(i1,i2,i3))
THEN ((i2 - i3) / (MAX(i1,i2,i3) - MIN(i1,i2,i3)))
ELSE IF (i2 = MAX(i1,i2,i3))
THEN 2 + ((i3 - i1) / (MAX(i1,i2,i3) - MIN(i1,i2,i3)))
ELSE 4 + ((i1 - i2) / (MAX(i1,i2,i3) - MIN(i1,i2,i3)))
) * 60 + 360) % 360
HSI Transform
IF MAX(i1,i2,i3) = 0 THEN 0 ELSE 1 -
MIN(i1,i2,i3) / MAX(i1,i2,i3)
MAX(i1,i2,i3)
Y = Ln Kanal 1 + Ki/Kj * Ln (Kanal 2)
Ki/Kj = a + (a2 + 1)1/2
a = (Var B1 – Var B2) / (2*CovB1B2)
Water Column Correction
and Lyzenga Transform
Image Transform
Algorithms
Manta Taw
Line Intercept Transect
Field Survey (June and July 2009)
Method:
- Manta Taw (85 stations)
- Line Intercept Transect (4 stations, 20m length, 3m and 10m depth)
- Bathymetry Survey
Shallow Marine Habitat Highlight Using
Hue Saturation Intensity
321 Standard RGB
HSI Transform
PC 1, 2 and 3
TansformLyzenga Transform
HSI Transform
Coral Reef Identification
Coral Reef
Seagrass
Coral Reef and
Seagrass Associate
Sand (shallow water)
Lagoon
Coral Reef
with Lower % Cover
Coral Reef in
Lagoon area
Coral Reef Identification
Coral Reef
Seagrass
Sand (shallow water)
Lagoon
Sample Area
Tengah Island
Kongsi Barat Island
Burung Island
Training Area Coral Reef on Image of HSI Transform
Coral Reef Position on
Scatter Plot Diagram
Coral Reef Extraction
Base on It’s Position
on Scatter Diagram
Clumped Position of Coral Reef on the Scattergram
Red Channel
Ne
ar
infr
are
d C
ha
nn
el
Red Channel
Ne
ar
infr
are
d C
ha
nn
el
Base on 1.031.688 pixel on
the image data
Coral Reef Extraction Base on
Spectral Respond (Yellow)
ALOS AVNIR 2008
Tengah Island
Kongsi Barat Island
Burung Island
Tikus Island
Coral Reef Area Extraction Base on
Spectral Respond (Yellow)
ALOS AVNIR
Tengah Island
Kongsi Barat Island
Burung Island
Tikus Island
Coral Reef Thematic Layer (Yellow)
ALOS AVNIR 2008
Tengah Island
Kongsi Barat Island
Burung Island
Tikus Island
Algorithm of Coral Reef Extraction
If (Green Channel > 68.8) and (Green Channel < 96.7)
and (Infrared > 8.9) and (Infrared Channel < 20.9) then
i1 else NULL
Blue-NIR Scatter Green-NIR Scatter
Red-NIR Scatter
Coral Reef Coral Reef
Coral Reef
Comparison of
AVNIR band
combination for
Coral Reef position
in the scattergram
Coral Reef
LandShallow to deeper
Low to Higher % Cover
Low to Higher % Cover
Associated Coral Reef
and Seagrass
Spectral Respond
Characteristic of Coral Reef
Red Channel
Ne
ar
infr
are
d C
ha
nn
el
Averages Signature
Of Coral Reef in
ASTER-AVNIR
Blue Band Green Band Red Band NIR Band
Co
ral
Reef
Sea G
rass
Lag
un
a
San
d o
f S
hall
ow
wate
r
Sea G
rass
La
gu
na
La
gu
na
A
B
Reflectance Characteristics
Of Coral Reef Ecosystem in
ASTER-AVNIR
Coral Reef Map Comparison
Coral Reef Classes base on
Exponential Attenuation Model Data
using Unsupervised Classification
Coral Reef Extraction base on
HSI Image
Mixing with lagoon
Unclassified as coral reef
It was caused by Blue
Channel on Lyzenga
Transform
Accuracy Assessment
Map
Coral
Reef
Sea
Grass
Sand Total Omi-
tion
Comi-
tion
Accu-
racy
(%)Survey
Coral Reef 34 2 2 38 10,53 15,79 77,27
Sea Grass 3 29 1 33 12,12 6,06 80,56
Sand 3 0 11 14 21,43 21,43 64,71
Total 40 31 14 85 87.06
Map
Coral
Reef
Sea
Grass
Sand Total Omi-
tion
Comi-
tion
Accu-
racy
(%)Survey
Coral Reef 37 1 0 38 2,63 10,53 88,09
Sea Grass 2 31 0 33 6,06 3,03 91,17
Sand 3 0 11 14 21,43 7,14 73,3
Total 41 32 11 85 92,94
Percentage Cover of Live Coral Species , 2009Coral reef cover on Pari Islet is 249,9 ha
Stasiun 4 Stasiun 2
Stasiun 1 Stasiun 3
Coral reef covers in Pari islets were
249.9 ha (26.5%), seagrass 313.6 ha
(33.3%) and sand of shallow water
378.9 ha (40.2%).
Spectral characteristic of green and red
band is much better on differentiating
between coral reef and other shallow
water substrate compared to the other
bands (blue and near-infrared).
Conclusion
Visually coral reef identification on HSI
transform is better compared to on PCA and
Lyzenga transform.
Accuracy of coral reef map on HSI is higher
(88.1%) than Lyzenga (77.3%).
Spectral values of coral reef on scattergram
were clumped on specific location, can be
differentiated from other shallow water
substrates and extracted base on that position.
Conclusion
Thank You