GIS CONCEPTS & ASSORTED CONSPECTS .pptx

Geography is the study of Earth’s features and patterns of their variations in spatial
location and time. Many questions of agricultural production are geographic in nature as the
production depends on the environment and prevailing socio economic conditions, both of
which vary spatially and in time

1. GENERAL GIS CONCEPTS by CH KALI PRASAD MAPPING PROFESSIONAL

2. 2 INDEX

3. Planet Earth has Seven Billion people today. Who else are living with us? 3 PLANET EARTH IN PERSPECTIVE

4. What else are associated with us? Where are they? How big are they? How much more Danger can we bear to keep fit and healthy? 4 THE EARTH AND ITS ENVIRONMENT

5. Do you have an answer how can we monitor, model these occurrences on the earth with respect to o ur lives? Is there any method or system which helps us to record, plan and model the phenomenon happening around us? 5 The answer is “ G eographic I nformation S ystem .” THE EARTH AND ITS ENVIRONMENT

6. GIS stands for [ ] [ ] [ ] A GIS stores geographic information in a [ ] a nd displays it on a map. GIS maps are [ ]. A GIS stores two type of geographic information: features and [ ] The functions of GIS are [ ], geo-data [ ] and Geographic [ ]. People use the information from a GIS to make decisions and [ ] Problems. 6 WHAT IS THE DEFINITION OF GIS? analysis attributes database dynamic geographic information management solve system visualization geographic information system database dynamic attributes solve v isualizatio n management analysis * Source ESRI

7. 7 PRINCIPAL APPLICATIONS AREAS OF GIS

8. 8 PRINCIPAL APPLICATIONS AREAS OF GIS

9. 9 GIS AND OTHER INFORMATION SYSTEMS A major difference between GIS and other information systems is that GIS can simulate the real world with its capability to construct and maintain the spatial relationship of real world features In early graphics systems, the data model was simple and consisted almost entirely of symbolized graphic features General-purpose, spatial data management requires a database structure & software technology beyond the graphic functionality . A GIS data model involves storage of tabular data (attributes) in association with very simple cartographic features (points, lines, and polygons)

10. 10 GIS data model, while similar to CAD approach in that it uses coordinates, is fundamentally different in its simplicity & approach Common to the GIS is the use of topology (networks) to store relationships among various spatial objects Topology involves the use of graph theory to abstract & relate cartographic objects using a series of arcs and nodes This represents a different and superior structure for geographic data management as compared with the “ graphics model ” GIS AND OTHER INFORMATION SYSTEMS

11. 11 A GEOGRAPHIC APPROACH [1] There are many problems that challenge our world and its future To combat these problems we need understanding knowledge, and integrated approaches

12. By combining the science of geography with the technology of GIS, we can Collect and organize the data for better understanding of the Earth . Analyze data to create geographic knowledge. Apply geographic knowledge to find solutions we call this as “ a geographic approach ” 12 A GEOGRAPHIC APPROACH [2]

13. Today a wide variety of disciplines and Organizations use geographic approach to Automate workflows Organize key information Use recourse wisely Make and support decisions 13 A GEOGRAPHIC APPROACH [3]

14. 14 A GIS has 3 primary functions FUNCTIONS OF GIS [1] Visualization Looking at different views of your geographic data. Visualization allows you to gain information and see relationships. Geo data management Organizing and updating geographic data to make it useful. Analysis Applying GIS tools to geographic data to answer questions and make decisions.

15. Suppose you own several book shops and you want to expand in the same city. Where are potential areas for a new shop? First map existing book shop locations, demographic data, city zoning data 15 FUNCTIONS OF GIS [2] Existing book shop locations Demographic data City zoning

16. Then use GIS tools to combine the data and find areas that meet your criteria 16 FUNCTIONS OF GIS [3] Map showing potential areas for new book stores Potential areas for a new book store

17. 17 TOPIC 2: COMPONENTS AND SUB SYSTEMS OF GIS

18. 18 INDEX

19. 19 COMPONENTS OF GIS A Geographic Information System is a system of computer software, hardware and data, and the personnel that make it possible to enter, manipulate, analyze, and present information that is tied to a location on the earth’s surface.

20. 20 HARDWARE/SOFTWARE Hardware is the computer on which a GIS operates. The software runs on a wide range of hardware types, from centralized computer servers to desktop computers used in stand-alone or networked configurations. GIS software provides functions and tools needed to input and store geographic information. It also provides query tools, performs analysis, and displays geographic information in the form of maps or reports Hardware software http://www.clker.com/clipart-1796.html

21. 21 DATA Data is one of the most important, and often most expensive, components of a GIS. Geographic data, which is comprised of geographic features and their corresponding attribute information, is entered into a GIS using a technique called digitizing. Digitizing is done by tracing the location, path or boundary of geographic features either on a computer screen using a scanned map in the background, or a paper map that is attached to a digitizing tablet. a ema-inc.com GIS data Digitization . http://proceedings.esri.com/library/userconf/proc01/professional/papers/pap894/p894.htm

22. 22 PEOPLE AND METHODS The real power of a GIS comes from the people who use them. Today GIS is being used by people, in many different fields, as a tool that enables them to perform their jobs more effectively. GIS users range from technical specialists who design and maintain the system to those who use it to help them do their everyday work. A successful GIS operates according to a well-designed plan and business rules, which are the models and operating practices unique to each organization . lagic.lsu.edu

23. 23 GIS SUBSYSTEMS

24. Allows the user to capture, collect, and transform spatial and thematic data into digital form 24 DATA INPUT

25. The data storage and retrieval subsystem organizes spatial and attribute data 25 DATA STORAGE AND RETRIEVAL

26. Allows the user to define and execute spatial and attribute procedures to generate derived information. Commonly thought of as the heart of a GIS Distinguishes GIS from other database information systems and Computer Aided Drafting (CAD) systems. 26 DATA MANIPULATION AND ANALYSIS

27. GIS output contains the following Maps Reports C harts 27 DATA OUTPUT AND DISPLAY

28. 28 TOPIC 3: AN INTRODUCTION TO GIS DATA MODELS

29. 29 INDEX

30. All spatial data models are approaches for storing the spatial location of geographic features in a data base. Three basic types of spatial data models have evolved for storing geographic data digitally . Vector Raster TIN 30 DATA MODELS [1]

31. Vector Representation X-AXIS 500 400 300 200 100 600 500 400 300 200 100 Y-AXIS River House 600 Trees Trees B B B B B B B B G G BK B B B G G G G G Raster Representation 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 Real World G G DATA MODELS [2] 31

32. Vector data model: Vector data model represents geographic objects with the basic elements points, lines and areas, also called polygons. 32 Point line Polygon DATA MODELS [3]

33. A city can be represented as a point A river can be represented as a line 33 VECTOR DATA MODEL A country can be represented as a polygon

34. Raster datasets represent geographic features by dividing the world into discrete square or rectangular cells laid out in a grid. Each cell has a value that is used to represent some characteristic of that location. Raster data includes images and grids. 34 RASTER DATA MODEL[1]

35. Grids represent derived data and are often used for analysis and modeling. Grids can store continuous values, such as for an elevation They can also store categories, such as for a grid of vegetation types. 35 RASTER DATA MODEL[2]

36. 36 Data can be represented at its original resolution and form without generalization. Due to the nature of the data storage technique data analysis is usually easy to program and quick to perform. For effective analysis, vector data must be converted into a topological structure. This is often processing intensive and usually requires extensive data cleaning The inherent nature of raster maps, e.g. one attribute maps, is ideally suited for mathematical modeling and quantitative analysis. Accurate geographic location of data is maintained. Discrete data, e.g. forestry stands, is accommodated equally well as continuous data, e.g. elevation data, and facilitates the integrating of the two data types Graphic output is usually more aesthetic Most output maps from grid-cell systems do not conform to high-quality cartographic needs. VECTOR vs RASTER DATA MODELS

37. TIN model is somewhat more complex than the simple point, line, and polygon vector model, or the raster model, it is actually quite useful for representing elevations. A triangulated irregular network (TIN) is a data model that is used to represent three dimensional objects. In this case, x,y, and z values represent points. Using methods of computational geometry, the points are connected into what is called a triangulation, forming a network of triangles. 37 TIN MODELS TIN data model

38. On a GIS map, there's more to a feature than its location and shape. There's all the information associated with that feature. For a road, this might include its name, speed limit, and whether it's one-way or two-way. For a city, this might include its population, demographic characteristics, number of schools, and average monthly temperatures. 38 GIS MAPS-ATTRIBUTES [1]

39. A particular type, or category, of information associated with a feature in a GIS is called an attribute. For example, population can be an attribute of a city, country, continent, and other features. Feature attributes are stored in an attribute table. 39 GIS MAPS-ATTRIBUTES [2]

40. A feature on a GIS map is linked to its record in the attribute table by a unique numerical identifier (ID) Because features on the map are linked to their records in the table, you can click a feature on the map and see the attributes stored for it in the table. When you select a record in the table, the linked feature on the map is automatically selected as well 40 GIS MAPS-ATTRIBUTES [3]

41. A separate data model is used to store and maintain attribute data for GIS software. Tabular Hierarchical Network Relational Object Oriented 41 ATTRIBUTE DATA MODEL

42. 42 TOPIC 4: TOPOLOGY

43. 43 INDEX

44. It is believed that a topologic data model best reflects the geography of the real world and provides an effective mathematical foundation for encoding spatial relationships, providing a data model for manipulating and analyzing vector based data. 44 TOPOLOGY http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=topology%20basics

45. In essence Topology is a mathematical approach that allows us to structure spatial data based on the principles of feature adjacency and feature connectivity. It is in fact the mathematical method used to define spatial relationships. For example, some common spatial relationships and rules include the following: Parcels cannot overlap. Adjacent parcels have shared boundaries Stream lines cannot overlap and must connect to one another at their endpoints. Road centerlines must connect at their endpoints. Each of these situations defines a potential case for using topology rules to maintain data integrity. 45 TOPOLOGY

46. 46 COMMON TOPOLOGICAL DATA MODELS Source: http://www.fpa.nifc.gov/

47. 47 TOPOLOGICAL ELEMENTS Single arcs Connected set of arcs Polygons bounded by arcs The most common topological data structure is the arc/node data model. This model contains two basic entities, the arc and the node . The arc is a series of points, joined by straight line segments, that start and end at a node . The node is an intersection point where two or more arcs meet. Nodes also occur at the end of a dangling arc. A polygon feature is comprised of a closed chain of arcs.

48. 48 TOPOLOGY STORAGE In GIS software the topological definition is commonly stored in a proprietary format most software offerings record the topological definition in three tables The node table stores information about the node and the arcs that are connected to it The arc table contains topological information about the arcs. The polygon table defines the arcs that make up each polygon. dusk.geo.orst.edu Arc/node map data structure with file – GRAPHIC

49. 49 TOPIC 5: THEMATIC MAPS

50. Transforming Business - Enriching Lives 50 INDEX

51. 51 THEMATIC MAPS Thematic maps are used to communicate geographic concepts like the distribution of densities, spatial relationships, magnitudes, movements etc. World climate or soils maps are notable examples of thematic maps. There are five common techniques for depicting geography data on a thematic map. The most common is a choropleth map that uses color to show variations in quantity, density, percent, etc. within a defined geographic area. Each color usually depicts a range of values. Soil map of India

52. 52 There are many different types of thematic maps. Each uses a different symbol to depict information. Four of the most common types are given below TYPES OF THEMATIC MAPS Choropleth map Dot maps Graduated circle maps Isoline maps

53. 53 TOPIC 6: DATA QUALITY

54. Transforming Business - Enriching Lives 54 INDEX

55. 55 DATA QUALITY The Implications of using low-quality data in important decisions is potentially severe. There are certain terms which defines the quality of GIS data Completeness Logical consistency Positional accuracy

56. 56 COMPLETENESS Completeness refers to whether there are data lacking in the data base to what exists in the real-world It is important to be able to assess what does and what does not belong to a complete data set as intended by it’s producer. It might be incomplete or over complete within the scope of the data set as it is defined. Completeness can relate to either spatial, temporal or thematic aspects of data set.

57. 57 LOGICAL CONSISTENCY For any particular application predefines logical rules concerns ,these include: The c ompatibility of data with other data in a data set The absence of any contradictions within a data set The topological consistency of the data set The allowed attribute value ranges as well as combinations of attributes

58. 58 POSITIONAL ACCURACY All measurements made with surveying and photogrammetric instruments are subject to error These include: Human errors for measurements generally referred to as gross errors or blunders. these are usually large errors resulting from carelessness which would be avoided through careful observation Instrumental or systematic errors This leads to errors that vary systematically in sign or magnitude .systematic errors are particularly dangerous because they tend to accumulate. Random errors caused by natural variations in the quantity being measured. these are effectively the errors that remain after blunders and systematic errors have been removed.

59. 59 TOPIC 7: META DATA, DEVICES AND FILE TYPES

60. 60 METADATA Metadata is defined as background information that describes all necessary information about the data it self. more generally it is known as “data about data” This includes Identification information : Data sources, time of acquisition , etc. Data quality information : Positional, attribute and temporal accuracy, lineage Entity and attribute information : Related attributes, unit of measure ,etc.

61. 61 Meta data answer who what , when, where ,why and how questions about all facets of the data Maintaining meta data is an key part in maintaining data and information quality in GIS. This can serve different purpose from description of data it self through providing instruction for data handling. METADATA

62. Digitizers: A digitizer is the device used for digitizing features from a hard copy map, Scanners: scanners sometimes can replace digitizing by automatically converting hard-copy maps to a digital raster file printer/plotter: These devices are used to produce a hardcopy map optical disks, magnetic disks used to store the information 62 DEVICES AND FILE TYPES

63. The format of the file describes in which way the geographical features have been saved. It is very important to consider the file format of GIS data because software programs rarely support all file types If you want to use GIS data that was saved in a particular format not supported by your GIS program, you must either find a way to transform the data or simply use another GIS program. most GIS programs support other formats by having functions to import and export datasets. Below is a list of some of the most common GIS file formats 63 DEVICES AND FILE TYPES

64. 64 VECTOR FILE FORMATS File format Name Description ARC ESRI Generate Line Simple ASCII format which can handle point and line data. DGN MicroStation Design Files DGN is an intern format for MicroStation, a CAD program DLG Digital Line Graphs DLG is used by the US Geological Survey (USGS) for handling vector information from printed paper maps DWG Autodesk Drawing Files DWG is an intern format for AutoCAD. AutoCAD can convert DWG files to DXF files without loosing graphic information E00 ARC/INFO interchange file E00 is a transfer format available both as ASCII and binary form. SHP ESRI shapefile Shape is Arc View's internal format for vector data. WMF Microsoft Windows Metafile WMF is a vector file format for Microsoft Windows Operation Systems

65. Raster files are used generally to save images, like for example, a scanned paper map, digital photographs or satellite images, but also to save variables which continuously vary in space, like topography and temperature. Images from satellites, or other aircrafts, are known as remote sensing data. The resolution of the remote sensing data and scanned maps refers to the area on the ground covered by one pixel. This differs to other image data, where the resolution is given in dots per inch (dpi). 65 RASTER FILE FORMATS

66. File format Name Description ADRG Arc Digitized Raster Graphics ADRG is a format created by the US military to save paper maps in raster format BIL Band Interleaved by Line BIL is a computer compatible tape (CCT) format that stores all bands of remotely sensed data in one image file. BIP Band Interleaved by Pixel the BIP image format, each line of an image is stored sequentially BSQ Band Sequential BSQ is a computer compatible t ape (CCT) format that stores each band of satellite data in one image file for all scan lines in the imagery array DEM Digital Elevation Model DEM is a raster format created by the USGS (US Geological Survey) for saving elevation data GeoTIFF GeoTIFF GeoTIFF is a form of TIFF (Tag Image File Format) format for geo-referenced raster data TIFF Tagged Image File Format Like PCX, TIFF is a common raster format produced by drawing programs and scanners 66 RASTER FILE FORMATS

67. 67 GEOGRAPHIC INFORMATION SYSTEM MATTERS Today’s challenges to safe guard these Seven Billion People…. require geographic approach to Model our Earth for… Climate Change Urban Growth Sustainable Agriculture Water Quality and Availability International & National Security Energy Epidemiology/Disease Tracking Natural Hazards: Seismicity, Weather Events http://yohipster.com/wp-content/uploads/2011/10/7_billion.png   engineeringchallenges.org

68. THANK YOU