1. GEOGRAPHICAL INFORMATION SYSTEM
UNIT 1
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2. WE-IT TUTORIALS (PH:8097071144/55)

3. What is GIS
A geographic Information system (GIS) is a computer system for capturing, storing, querying, analyzing, and displaying geospatial data.
The ability of a GIS to handle and process geospatial data distinguishes GIS from other infor­mation systems
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4. applications of GIS GIS has been important in
natural resource management including land-use planning
natural hazard assessment
wildlife habitat analysis
riparian zone monitoring
and timber management
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5. components of GIS
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6. Spatial Data? Vs Attribute Data?
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7. GIS Operations
Spatial Data Input (Data entry, Geometric transformation, Projection )
Attribute data management (verification, Attribute data manipulation )
Data display (Cartographic symbolization, Map design )
Data exploration (Attribute data query , Spatial data query, Geographic visualization )
Data analysis
Vector data analysis: buttering, overlay, distance measurement, spatial statistics, map manipulation
Raster data analysis: local, neighborhood, zonal, global, raster data manipulation
GIS modeling (Binary models ”DIFFERENCE ”, Index models “VALUE CALCULATION”, Regression models “DEPENDANCY”, Process models ”RELATIONSHIP”)
Binary models
A binary model uses logical expressions to select map features from a composite map or multiple grids.
Map overlay to prepare for vector query
Multiple grid process for raster
Siting common application with multiple criteria (example Conservation Reserve Program)
Binary models can be used for change detection.
Sometimes binary models are used at the beginning stage of modeling.
Index Models
An index model used the index value calculated from a composite map or multiple grids to produced a ranked map.
Selected variables are evaluated at two levels
Relative importance, assigning a weight
Observed values are evaluated and given scores.
ArcView Model Builder
Suitability and vulnerability analysis
Regression Models
Regression model relates a dependent variable to a number of independent variables in an equation.
Linear regression is used when the dependent variables and independent variables are all numeric.
Logistic regression is used when the dependent variable is a binary phenomenon and the independent variables are categorical or numeric.
Process Models
A process model integrates existing knowledge about the environmental processes in the real world into a set of relationships and equations for quantifying the process.
Universal Soil Loss Equation (USLE)
Agricultural Nonpoint Source (AGNPS)
Soil and Water Assessment Tool (SWAT)
Typically raster-based
Most commercial GIS do not offer.
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8. Geographic Coordinate System
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9. Datum
A geodetic datum (plural datums, not data) is a reference from which spatial measurements are made. In surveying and geodesy, a datum is a set of reference points on the earth's surface against which position measurements are made, and (often) an associated model of the shape of the earth to define a geographic coordinate system.
Horizontal datums are used for describing a point on the earth's surface, in latitude and longitude or another coordinate system.
Vertical datums measure elevations or depths. In engineering and drafting, a datum is a reference point, surface, or axis on an object against which measurements are made.
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10. map projections ?
a method for representing part of the surface of the earth or a celestial sphere on a plane surface.
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11. Types of Map Projections
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12. Projected Coordinate System
A Projected coordinate system (PCS) is a two-dimensional planar surface. However, the Earth's surface is three-dimensional. Transforming three-dimensional space onto a two-dimensional surface is called projection.
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13. State Plane Coordinate System
State Plane Coordinate System (SPCS) is not a projection (also known as SPC, State Plane, and State). It is a coordinate system that divides the 50 states of the United States
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14. Public Land Survey System (PLSS)
The Public Land Survey System (PLSS) is the surveying method used historically over the largest fraction of the United States to survey and spatially identify land parcels before designation of eventual ownership, particularly for rural, wild or undeveloped land. It is sometimes referred to as the rectangular survey system
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15. Vector Data Model ? Vector model Points, lines, polygons
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16. TIGER DATABASE
Topologically Inte­grated Geographic Encoding and Referencing
Topology in the TIGER database involves 0- cells or points.
1-cells or lines, and 2-cells or areas.
Address ranges and ZIP codes in the TIGER database have the right- or left- side designation based on the direction of the street.
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17. Raster Data Model
a raster is divided into rows, columns, and cells. Cells are also called pixels with images
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18. Why use Raster Overlay Analysis/Overlay Operations
Arithmetic Operations
Addition
Subtraction
Division
Multiplication
Logical (Boolean) Operations
Where conditions occur or do not occur together
AND, OR, NOT, GT, LT, etc.
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19. TYPES OF RASTER DATA Satellite Imagery Digital Elevation Models
Non-USGS DEMs(plotting)
Global DEMs(global scale)
Digital Orthophotos
Bi-Level Scanned Files(scanned image)
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20. Encoding types in Raster
Cell by Cell Encoding
Run-length Encoding
Quad tree
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21. END OF UNIT 1
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