Introduction to Geographic Information System (GIS)
- 1. Basics of GIS Professor Dr Md Shahedur Rashid Jahangirnagar University m.s.rashid@juniv.edu
- 2. GIS--What is it? • Geographic/Geographical/Geospatial Information – information about places on the earth’s surface – knowledge about “what is where when” – Geographic/geospatial: almost synonymous • GIS--what’s in the S? – Systems: technology oriented – Sciences: concepts and theory – Studies: applications of GIS – Society: movement and awareness building – Service: fulfilling the GIS related public needs
- 3. 3 A flow diagram of the DIKW hierarchy; where d : data, i : information, k : knowledge, u : understanding, w : wisdom, t : tacit knowledge, and e : explicit knowledge http://en.wikipedia.org/wiki/DIKW_Pyramid#/media/File:DIKW.png DIKW MODEL : Status of Information
- 4. Defining Geographic Information Systems (GIS) • The common ground between information processing and the many fields using spatial analysis techniques. (Tomlinson, 1972) • A powerful set of tools for collecting, storing, retrieving, transforming, and displaying spatial data from the real world. (Burroughs, 1986).
- 5. A GIS integrates five basic components data methods software people hardware
- 6. Data
- 7. Data - Data - Data We all ‘got data’ • Location Data – How Many – What Kind – Where • Scale of Data – Local to Global • Data Presentation – Words, Charts, Graphs, Tables, or Maps • Exploring data using GIS turns data into information into knowledge
- 8. Database “Not Easy to Interpret”
- 9. Visualization “Worth a Thousand Words”
- 10. • Raster – Grid – “pixels” – a location and value – Satellite images and aerial photos are already in this format • Vector – Linear – Points, lines & polygons – “Features” (house, lake, etc.) • Attributes – size, type, length, etc. Real world Two Ways to Input and Visualize Data The World in GIS
- 11. Combining Data From Many Sources
- 12. Data For GIS Applications • Digitized and Scanned Maps – purchased, donated, free (Internet) – created by user • Data Bases – Tables of data • GPS – Global Positioning System – accurate locations • Field Sampling of Attributes • Remote Sensing & Aerial Photography
- 13. “Spatial Analysis” – not just a map Turning Data Into Information
- 14. Asking A Question – Interaction
- 15. Maps and Database are “Interactive”
- 16. Multiple Databases can be Linked and Related
- 17. Data vs. Information • Data, by itself, generally differs from information. • Data is of little use unless it is transformed into information. • Information is an answer to a question based on raw data. • We transform data into information through the use of an Information System.
- 18. Types of datasets Vector formats (“feature classes”) Points Lines (”arcs”) Polygons
- 19. Types of datasets Raster formats Matrices of square cells (grids, pixels)
- 20. Types of datasets Attribute tables: tables of data describing spatial features
- 27. Methods
- 29. Capturing data Paper maps Digital images GPS output Coordinate lists
- 30. Query Identifying specific features Where is parcel No. 2945? Identifying features based on conditions Find all trees with DBH > 35 cm
- 31. Analysis Proximity : which roads are within a 100 ft from a stream Overlay: combines the features of two or more layers to create a new layer (intersections, unions…) Network: examines how linear features are connected
- 32. Analysis
- 33. Analysis
- 34. Display • Maps • Graphs • Reports/Tables
- 35. Examples of GIS maps surface drapes & 3-D modeling
- 36. Examples of GIS generated maps detailed topographic maps
- 37. What GIS Applications Do: manage, analyze, communicate • make possible the automation of activities involving geographic data – map production – calculation of areas, distances, route lengths – measurement of slope, aspect, viewshed – logistics: route planning, vehicle tracking, traffic management • perform complex spatial modelling (what if scenarios for transportation planning, disaster planning, resource management, utility design)
- 38. Why Study GIS? • 80% of local government activities estimated to be geographically based – plats, zoning, public works (streets, water supply, sewers), garbage collection, land ownership and valuation, public safety (fire and police) • a significant portion of state government has a geographical component – natural resource management – highways and transportation • businesses use GIS for a very wide array of applications – retail site selection & customer analysis – logistics: vehicle tracking & routing – natural resource exploration (petroleum, etc.) – precision agriculture – civil engineering and construction • Military and defense – Battlefield management – Satellite imagery interpretation • scientific research employs GIS – geography, geology, botany – anthropology, sociology, economics, political science – Epidemiology, criminology
- 39. The major areas of GIS application • Local Government – Public works/infrastructure management (roads, water, sewer) – Planning and environmental management – property records and appraisal • Real Estate and Marketing – Retail site selection, site evaluation • Public safety and defense – Crime analysis, fire prevention, emergency management, military/defense • Natural resource exploration/extraction – Petroleum, minerals, quarrying • Transportation – Airline route planning, transportation planning/modeling • Public health and epidemiology • The Geospatial Industry – Data development, application development, programming
- 40. Examples of Applied GIS • Urban Planning, Management & Policy – Zoning, subdivision planning – Land acquisition – Economic development – Code enforcement – Housing renovation programs – Emergency response – Crime analysis – Tax assessment • Environmental Sciences – Monitoring environmental risk – Modeling stormwater runoff – Management of watersheds, floodplains, wetlands, forests, aquifers – Environmental Impact Analysis – Hazardous or toxic facility siting – Groundwater modeling and contamination tracking • Political Science – Redistricting – Analysis of election results – Predictive modeling • Civil Engineering/Utility – Locating underground facilities – Designing alignment for freeways, transit – Coordination of infrastructure maintenance • Business – Demographic Analysis – Market Penetration/ Share Analysis – Site Selection • Education Administration – Attendance Area Maintenance – Enrollment Projections – School Bus Routing • Real Estate – Neighborhood land prices – Traffic Impact Analysis – Determination of Highest and Best Use • Health Care – Epidemiology – Needs Analysis – Service Inventory
- 41. Projection, Scale, Accuracy and Resolution the key properties of spatial data • Projection: the method by which the curved 3-D surface of the earth is represented by X,Y coordinates on a 2-D flat map/screen – distortion is inevitable • Scale: the ratio of distance on a map to the equivalent distance on the ground – in theory GIS is scale independent but in practice there is an implicit range of scales for data output in any project • Accuracy: how well does the database info match the real world – Positional: how close are features to their real world location? – Consistency: do feature characteristics in database match those in real world • is a road in the database a road in the real world? – Completeness: are all real world instances of features present in the database? • Are all roads included. • Resolution: the size of the smallest feature able to be recognized – for raster data, it is the pixel size The tighter the specification, the higher the cost.