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Comparison of vegetation indices for mangrove mapping using THEOS data Jiraporn Kongwongjun, Chanida Suwanprasit and Pun Thongchumnum Faculty of Technology and Environment, Prince of Songkla University, Phuket Campus APAN-33rd Meeting 1 Slide 2 Outline 1.Introduction 2.Objectives 3.Study area 4.Methodology 5.Result 6.Conclusion 7.Acknowledgement 2 Slide 3 The importance of mangroves Mangrove forests are useful as fishing areas, wildlife reserves, for recreation, human habitation, aquaculture and natural ecosystem. 1 42635 3 Slide 4 Mangrove vegetations 1 42635 (a) Rhizophora mucronata Poir I(b) Rhizophora apiculata Blume(c) Sonneratia ovata Backer (d) Rhizophora Ceriops Decandra (e) Rhizophora Bruguiera s. (Department of marine and coastal resource, 2011) 4 Slide 5 Vegetation indices 1 42635 The remote sensing is applicable for mangrove mapping. The vegetation indices (VIs) in forest areas have been widely used and provide accurate classification. Different VIs is suitable for different vegetation cover. 5 Slide 6 Objectives 14 2 635 To classify mangrove and non-mangrove areas. To find out a suitable vegetation index for identifying mangrove area. 6 Slide 7 Study area 1426 3 5 Pa Khlok sub-district, Phuket, Thailand 7 Slide 8 Study area 1426 3 5 source: www.technicchan.ac.th, 2011 source: http://cccmkc.edu.hk 8 Slide 9 Methodology 1 4 2635 Input THEOS data Pre-Image Processing Image classification Post classification Compare Image Output mapping data ROI Training Test 5 VIs NDVI SR SAVI PVI TVI unsupervisedsupervised K-mean Visual Interpretation 9 Slide 10 THEOS Satellite 1 4 2635 DescriptionMS Spectral bands and resolution4 multispectral (15 meters) Spectral rangesB1 (blue) : 0.45 -0.52 m B2 (green) : 0.53 0.60 m B3 (red) : 0.62 0.69 m B4 (NIR) : 0.77 0.90 m Imaging swath90 km. Image dynamics8 bits -12 bits Absolute localization accuracy (level 1B) < 300 m (1 s) Off-nadir viewing50 (roll and pitch) Signal to Noise Ratio>100 (Pitan, 2008) 10 Slide 11 1 4 2635 Band1: Blue 0.45 -0.52 m Band2: Green 0.53 0.60 m Band3: Red 0.62 0.69 m THEOS Spectral bands Band4: NIR 0.77 0.90 m 11 Slide 12 1 4 2635 Selection of ROIs ROIs Training pixels (50%) Test pixels (50%) Mangrove691 Non-mangrove water cloud on water cloud on land forest agriculture Others 1,364 13 132 1,118 387 88 1,364 13 132 1,118 387 88 Total3,661 12 Slide 13 1 4 2635 ROIs Table Class Mangrove Cloud (water) Cloud (land ForestAgriculturewaterOthers Mangrove -2.001.981.591.332.001.99 Cloud water 2.00- 1.99 Cloud land 1.982.00-1.981.962.001.98 Forest 1.612.001.99-1.721.99 Agriculture 1.292.001.971.71-1.99 water 2.001.992.001.99 - Others 1.99 1.981.99 - Training Sample ROITest Sample ROI 13 Slide 14 1 4 2635 ClassFormulasAuthors Normalized Different Vegetation Index (NDVI) (Pearson and Miller, 1972) Simple Ratio (SR) (Pearson and Miller, 1972) Soil Adjusted Vegetation Index (SAVI) (Huete, 1998) Perpendicular Vegetation Index (PVI) (Richardson and Wiegand,1977) Triangular Vegetation Index (TVI) 0.5(120(NIR-G) )-200(R-G)(Broge & Leblanc, 2000) 5 Vegetation Indices 14 Slide 15 1 4 2635 Vegetation Indices NDVISRSAVIPVITVI 15 Slide 16 14263 5 Image Classification K-mean MLC+NDVI MLC+SRMLC+SAVIMLC+TVI MLC MLC+PVI Classification 2 classes : mangrove and non mangrove areas Unsupervised Supervised Yellow = Non-mangrove Blue = Mangrove 16 Slide 17 14263 5 Overall accuracy ClassifiedOverall accuracyKappa coefficient Maximum Likelihood (MLC)96.46%0.9522 MLC+ NDVI96.78%0.9565 MLC+ SR96.78%0.9565 MLC + SAVI96.78%0.9565 MLC + PVI95.67%0.9417 MLC + TVI95.30%0.9364 17 Slide 18 142 6 35 Conclusion 18 NDVI, SR and SAVI are the best indices between mangrove and non-mangrove forests with 96.78% overall accuracy. THEOS with 15 m resolution is appropriate for visual interpretation. However, spectral resolution of 4 bands seems to give limited vegetation classification. Slide 19 142 6 35 Acknowledgement Faculty of Technology and Environment, Prince of Songkla university, Phuket campus, providing invaluable assistance during work Geo-Informatics and Space Technology Development Agency organization (GISTDA) UniNet Adviser and co-adviser in particular to Dr.Chanida Suwanprasit and Dr.Pun Thongchumnum who give suggestion and Dr.Naiyana Srichai and my graduate friends for encouragement. 19 Slide 20