WEB BASED GIS TOOLS FOR CHANGE DETECTION USING SATELLITE IMAGERY

DURING PRE AND POST FLOOD SCENERIES

EXTERNAL GUIDEDR.T.V. RAJINIKANTH

Presented byR.Manoj Kumar

INTRODUCTION

• What is GIS ?• “A system for capturing, storing, checking,

integrating, manipulating, analysing and displaying data which are spatially referenced to the Earth. This is normally considered to involve a spatially referenced computer database and appropriate applications software

GIS System Architecture and Components

Data Input

Query Input Geographic Database

Output: Display and Reporting

Transformation and Analysis

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GIS components

Specific applications /

decision making objectives

??G I SG I S

Spatial data

Computer Computer hardware / /

software toolssoftware tools

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Spatial data storage

• Vector model

• Raster model

point

1,6

2,5

5,4

4,1

7,105,9

4,7

6,68,6

9,8

line

polygon

2,2

5 10

5

10

as geometric objects: points, lines, polygons

as image files composed of grid-cells (pixels)

Vector data model• advantage of the vector data format: allows precise representation of

points, boundaries, and linear features. – useful for analysis tasks that require accurate positioning, – for defining spatial relationship (ie the connectivity and adjacency) between

coverage features (topology), important for such purposes as network analysis (for example to find an optimal path between two nodes in a complex transport network)

• main disadvantage of vector data is that the boundaries of the resulting map polygons are discrete (enclosed by well-defined boundary lines), whereas in reality the map polygons may represent continuous gradation or gradual change, as in soil maps.

Raster data model• good for representing indistinct boundaries

– thematic information on soil types, soil moisture, vegetation, ground temperatures

• as reconnaissance satellites and aerial surveys use raster-based scanners, the information (ie scanned images) can be directly incorporated into GIS

• the higher the grid resolution, the larger the data file is going to be

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Vector data

Land use parcels

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Raster data

Change Detection

• What is change detection ?Change detection is used to highlight or identify

significant differences in imagery acquired at different times; playing an important role in the lifecycle of GIS features and providing the capability to update feature data based on new imagery.

Land Cover Map

• Urban• Vegetation• Transportation• Utilities• Water Bodies• Wetlands• Barren Land• Vacant Land

Land Use Map Urban

-Residential-Industrial-Commercial-Services-Cemetery-Religions

Transportation-Roads-Bridges & Tunnels-Railways

Utilities-Power Lines-Petroleum & Gas

Land Cover Map

Vegetation-Agriculture-Natural Vegetation

Water-Fresh Water Bodies-Saline Water Bodies

WetlandsBarren LandVacant Land

GRIET 2003

GRIET 2005

GRIET 2007

GRIET 2007

GRIET 2008

GRIET 2010