"GIS Concepts"

1. "GIS Concepts"

2. GIS Definition • Many expert used GIS for his own demand and that is the reason that they define GIS in that context. • Aronoff (1989) gives a general description of GIS as “any manual or computer-based set of procedures used to store and manipulate geographically-referenced data.” • More specifically, Aronoff (1989) defines GIS as "a computer-based system that provides four sets of capabilities to handle georeferenced data: i) data input ii) data management (data storage and retrieval) iii) manipulation and analysis iv) data output.” • Cower (1988) defines GIS as “a decision support system involving the integration of spatially referenced data in a problem solving environment”.

4. COMPONENTS OF GIS • Several components are involved in GIS technology. • Hardware • A computer and the associated accessories are essential for handling spatial data in GIS. These devices are collectively known as hardware like scanners, CPUs, Digitizers, Workstations & plotters etc. • Software • Software refers to the programmes that run on computers; these include programmes to manage the computer and to perform specific functions. For example, DBMS, Corel draw, ILWIS, Arc/view, Mapinfow, ERDAS Imagine, IDRISI and Arc/info are specialised software programmes designed to perform certain tasks. Continued………

5. Database • A central theme to GIS is the database. A GIS database deals with spatial data. GIS facilitate integration of spatial and attribute data and this makes GIS unique in contrast to other database systems. The beauty of GIS technology lies in the ability to assimilate divergent sources of data and analyse them. • Human Input (live ware) • People who work with GIS form the most important component. GIS constitute truly a interdisciplinary field and require varied backgrounds of expertise, depending upon the applications. In addition, for technical management, a Hardware Specialist, System Administrator, and Database Manager are required for corporating the GIS set-up. • Policy and Procedures • A methodology is must to derive the results users need. Basically, this includes spatial analysis for the particular application. By and large, this depends upon the institutional framework and its interest in exploiting GIS technology for decision-making

6. HARDWARE Geographic Information Systems IDRISI ILWIS ARC/ INFO GIS PEOPLE SOFTWARE POLICY AND PROCEDURES FOR RESOURCE MANAGEMENT DATA

7. GIS Historical Development Earth Science Computer Science Geography CAD/CAM Remote Sensing Spatial Mathematics GIS Military Studies Cartography Urban Planning Surveying and Photogrammetry Civil Engineering

9. Components of GIS GIS ABSTRACTION OR SIMPLIFICATION USERS + SOFTWARE DATABASE TOOLS THE REAL WORLD RESULTS

10. Modeling Measurements Mapping Monitoring Time-1 Time-2 Time-3 Updating Landuse Soil Topography The four Ms. Measurement, Mapping, Monitoring and Modeling of environmental features and processes can be enhanced through the use of a GIS Spatial Analyses GEOGRAPHIC INFORMATION SYSTEM Adapted from J.Stars and J.Estates FOUR Ms

11. GIS A computer based system capable of holding and using data describing places on the earth’s surface The real world consists of many geographies which can be represented as a number of related data layers. Hydrology Landuse Districts Topography Soils GIS IS SUPPORTING TOOL FOR DECISION MAKERS

12. Geology Satellite images -Analysis Hydrology Point Thematic object selection Area Soil Line Statistical tables Cartographic processing .- Generalization - Symbolization Aerial photographs Attribute tables Maps Real world Field Survey GPS Decision makers HOW GIS WORKS GIS operations

13. MAPS AND SPATIAL DATA Topographic Parcels Contour lines REAL-WORLD

14. Questions a GIS can answer • Location • Condition • Trends • Patterns • Modelling

19. Geographic Data

20. Types of GIS • Vector GIS • Raster GIS • Hybrid GIS Technology is moving towards hybrid GIS Raster Vector Integration

21. Vector Representation The Vector Data Model Features of Spatial Object Points (Example : Location of house) Lines(Example : Railway) Polygons (Examples : Forest area) The location of features on the earth’s surface are referred to map positions using an XY coordinate system (termed a Cartesian Coordinate System). PointA Singly XY pair LineSeries of XY pair PolygonA closed loop of XY coordinate pairs that define the boundary

22. Raster Representation § Row § Column § Cell Size § Resolution Buildings Road River

23. Attribute Data District Name Area Population Peshawar 395 sq. km. 6,75,341 Swabi 385 sq. km. 2,57,086 Dir lower 119 sq. km. 1,72,952  Industry Information Industry Information Agriculture CensusEducation and Health

24. Map: City blocks SPATIAL DATA City blocks Land use 001 Institutional 002 Commercial 003 Commercial 004 Residential 005 Residential 006 Residential 007 Industrial 008 Residential 009 Industrial 010 Industrial 011 Residential 012 Industrial 013 Residential 014 Residential 015 Residential NON-SPATIAL DATA SPATIAL AND NON-SPATIAL DATA

25. Risk area Cadastral parcel Land-use National park Soil Alternative 1 Alternative 2 Slopes Topography Alternative 3 Digital Terrain Model Decision makers THEN WHAT SHOULD BE THE BEST ROUTE, LEAVE IT UPTO GIS Analysis Analysis

26. Four Major GIS Functions data capture Ÿ - graphic data: digitised, converted from existing data - attribute data: keyed-in, loaded from existing data files data storage and manipulation Ÿ - file management - editing data analysis Ÿ - database query - spatial analysis - modelling data display Ÿ - maps - reports

27. WHAT ARE THE FUNCTIONS INVOLVED IN GIS • 1.INPUT OF DATA • Data collection (Both Geographical & Statistical) • Data verification • Data transfer • Data editing

28. WHAT ARE THE FUNCTIONS INVOLVED IN GIS • 2.DATA STORAGE • On hard disk • On floppy disk • On CDs

29. WHAT ARE THE FUNCTIONS INVOLVED IN GIS • 3.MANIPULATION OF DATA • Cartographic function a.Scale changes b.Vector-Raster changes c.Projection changes d.Map embellishment like adding north, title, scale and legend etc (continued….)

30. WHAT ARE THE FUNCTIONS INVOLVED IN GIS • 3.MANIPULATION OF DATA • Data integration (Core of GIS) a.Maps over laying b.Spatial transformation c.Spatial aggregation (continued……..)

31. HOW G.I.S. WILL ANALYSE THE DATA Example: Selection of waste disposal site for Peshawar cityunder the following conditions 1. The selected site should be located within 20 km distance from the city center, but further than 300 meters from any existing built-up area. 2. The site should be located on clay-rich soils, with a maximum thickness of 5 meters and clay content greater than 50%. 3.The site should have an area of at least 2 hectares. (Continue…..)

32. HOW G.I.S. WILL ANALYSE THE DATA Example: Selection of waste disposal site for Peshawar cityunder the following conditions 4. Should have an area, which do not have an important economic or ecological value. 5. Site should be located on a terrain with slope less than 20 degree to prevent erosion and to assure accessibility. 6. Should be free from active landslides.

33. HOW G.I.S. WILL ANALYSE THE DATA Following data are available for data input a. Contour map indicated in degrees b. Landuse map c. Road map d. Slide map with landslide distribution e. City map f. Geological map FORMULAS WILL BE USED AS Lslide=iff((slide=“dormant”)or(slide=“active”),1,0) Luse=iff((landuse=“barren”)or(landuse=“forest”),1,0)

34. SELECTION OF SUITABLE SITE FOR WASTE DISPOSAL

35. WHAT ARE THE FUNCTIONS INVOLVED IN GIS • 3.MANIPULATION OF DATA • Feature measurement a.Number of features b.Calculate distance, area c.Statistical analysis like crossing of tables and correction

36. WHAT ARE THE FUNCTIONS INVOLVED IN GIS • 4.DATA OUTPUT • Data presentation a.Maps b.Tables c.Diagrams DATA TRANSFERING/DATA SHARING

37. Principal Components and Functions of an Ideal GIS

38. "Rubbish in" "Rubbish out" YOU SHOULD BE CLEAR IN MIND WHILE ENTERING DATA INTO COMPUTER

39. GEOGRAPHIC DATA • Spatial and Non-Spatial data • There are two important components of geographic database: its geographic position and its attributes or properties. In other words, spatial data (where is it?) and attribute data (what is it?) • Analogue Data: A physical product displaying information • visually on paper like maps, aerial photos, imageries, • tabular data and written report etc. • Digital Data: Information derived from computer

40. Basic types of spatial Data • Maps model the real world with points, lines, and polygons. Symbols and labels describe the descriptive information about the geographic features. • Points • Points define the discrete locations of geographic features which are too small to illustrate as lines or polygons such as well or telephone poles. Points can be used to illustrate the locations of mountain peak or discrete elevation points. • Lines • Lines represent the linear features of geographic object too narrow to illustrate as polygons, such as streets and streams that have length but no area. Moreover, contour lines are represented as the lines • By using different symbols and labels, descriptive information of linear features are illustrated. For example: Roads are drawn with various line widths and patterns and colors to represent different road types, e.g., highway as wide solid red colour line, blue lines are used to illustrate the streams. The symbol can be used to illustrate the railway. • City streets are labeled with names and often address ranges.

41. Polygons • Polygons are closed features that represent the shape and location of homogeneous features such as landuse, forest types. Tone of the colour can be applied to illustrate the density of population, green color can be used to represent vegetation and blue colour can be used to illustrate lake. • Surfaces • A surface represents the elevation, presence or absence of something for every point on the piece of earth. The elevation models are best examples to illustrate as the surfaces. • Surfaces are typically represented on the maps as the series of isolines. Elevation contours, rainfall, temperature can be represented as the surface of isolines. • Surfaces can be represented as the Raster Elevation Model and Vector Elevation Model.

42. Geometry of Spatial Data Point Line surface Area

43. REPRESENTATION OF GEOGRAPHIC DATA • Vector Graphics: • Images are built-up from points, lines(segments) and areas (Polygons). • Each defined by pair of X-Y co-ordinates. • Preparing a map by digitization is converted into vector data in • computer. • Raster Graphics: • Images are built-up from cells which is called as Pixels. • In raster graphics, the smaller the area of land that each cell • represents, the higher the resolution of the data and higher the • spatial accuracy, ultimately the larger the files needed to store • the data.

45. Scanning (automatic digitizing) Y Editing Improving Vectorizing X Apply attributes Raster model Manual digitizing Improving Apply attributes Y Vector model Digital Landscape Model X SPATIAL DATA INPUT Sensor

47. Features Raster model)

48. RASTER MODEL VECTOR MODEL Advantages Advantages - easy and efficient overlaying - efficient for network analysis - compatible with RS imagery - efficient projection transformation - - accurate map output same grid cells for several attributes Disadvantages Disadvantages - inefficient use of computer storage - complex data structure - errors in perimeter, area, and shape - difficult overlay operations - difficult network analysis - not compatible with RS imagery - inefficient projection transformations - loss of information when using large cells - less accurate (although attractive) maps Advantages and Disadvantages of the Raster and Vector Data Models

49. APPLICATION OF GIS • Canada was the pioneer in development of GIS as a result of innovations dating back to the early 1960s. Much of the credit goes to Roger Tomilson for the early development of GIS. Although the field of GIS has been around for the last 25 years the real potentials have become apparent only since the late 1980s. Afterwards widely used in USA, Canada & Western Europe. • Some typical examples of GIS applications are; • land-use planning and management e.g. Cadestral mapping, Urban growth, Landuse changes etc. S.O.P, SUPARCO, P.D.A, C.D.A, P.E & D) • oil & mineral exploration (O.G.D.C, Oil companies, P.G.S) • environmental impact studies • management of water resources (IIMI, AKRSP, WAPDA) • natural hazard mapping (FFC, NESPAK) • forestry and wildlife management (FMC, PFI, AKRSP) • soil degradation studies (Soil survey of Pakistan) • monitoring desertification • agricultural development • socio-economic survey and mapping (S.O.P & Primary education project in NWFP, Baluchistan, Sind, N.As & A.K.)