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; helmi@waindo.co.id

**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