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Effectiveness of landscape Spatial Metrics with reference to the Spatial Resolutions of Remote Sensing Data |
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Bharath H. Aithal 1,2 Bharath Settur 1 Durgappa Sanna D.2 Ramachandra T V 1,2,3,*
1 Energy & Wetlands Research Group, Center for Ecological Sciences [CES],
2 Centre for Sustainable Technologies (astra),
3 Centre for infrastructure, Sustainable Transportation and Urban Planning [CiSTUP],
Indian Institute of Science, Bangalore, Karnataka, 560 012, India
*Corresponding author: cestvr@ces.iisc.ernet.in
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ANALYSIS
Preprocessing: The remote sensing data obtained were geo-referenced, rectified and cropped pertaining to the study area. Landsat ETM+ bands of 2010 were corrected for the SLC-off by using image enhancement techniques, followed by nearest-neighbour interpolation.
Land use analysis: The method involves i) generation of false colour composite (FCC) of remote sensing data (bands – green, red and NIR). This helped in locating heterogeneous patches in the landscape ii) selection of training polygons (these correspond to heterogeneous patches in FCC) covering 15% of the study area and uniformly distributed over the entire study area, iii) loading these training polygons co-ordinates into pre-calibrated GPS, vi) collection of the corresponding attribute data (land use types) for these polygons from the field. GPS helped in locating respective training polygons in the field, iv) supplementing this information with Google Earth v) 60% of the training data has been used for classification of the data, while the balance is used for validation or accuracy assessment.
Land use classification was carried out using supervised pattern classifier - Gaussian maximum likelihood algorithm. This classifier is superior as it uses various classification decisions using probability and cost functions (Duda et al., 2000). Mean and covariance matrix are computed using estimate of maximum likelihood estimator. Land use was computed using the temporal data through open source program GRASS - Geographic Resource Analysis Support System (http://wgbis.ces.iisc.ernet.in/grass/index.php). Four major types of land use classes were considered: built-up area, vegetation, open area, and water body. Application of this method resulted in accuracy of about 88% using Landsat data, 91% accuracy using IRS-P6 data, 94% accuracy using Ikonos data and 74% using Modis data. The accuracy assessment has been done through confusion matrix and kappa statistics.
Landscape Metrics: Landscape metrics were computed for the sample space considering multi-resolution data - MODIS data (500 m) was resampled to 250 m and 100 m Landsat resampled to 30 m and 15 m, Ikonos data resampled to 3 m and 2 m. The resampled data were considered for further analysis. Classified land use data was converted to ASCII format and metrics at the landscape level were computed with FRAGSTATS (McGarigal and Marks, 1995). The spatial metrics include the patch area, edge/border, shape, compact/contagion/dispersion.
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Citation : Bharath H Aithal, Bharath Setturu, Sanna Durgappa D and Ramachandra T. V., (2012), Effectiveness of landscape Spatial Metrics with reference to the Spatial Resolutions of Remote Sensing Data, Proceedings of India Conference on Geo-spatial Technologies & Applications 2012, IIT Bombay, Mumbai, India, 12-14 April, 2012.
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