地理信息系统 工程 GIS Engineering

1. 地理信息系统工程GIS Engineering Wuhan University School of Resource and environment Guo Qingsheng 武汉大学郭庆胜

2. What is GIS? • a cross disciplinary fieldto map out information , to think graphically and to build analytical solutions; to mode and to carry out prediction • set of tools for storing and retrieving at will, • transforming and displaying spatial data from the real world for a particular set of purposes.(Peter Burrough, 1986) • A special IS where the database consists of observations on spatially distributed features, activities or events which are definable in space as points, line or areas. (Dueker, 1979)A GIS manipulates these data.

3. What is a GIS A system of hardware, software, and procedures designed to support the capture, management, manipulation, analysis, modeling and display of spatially-referenced data for solving complex planning and management problems. (NCGIA lecture by David Cowen, 1989) GISystem– GIScience--GIServer

4. Four ways to view GIS [Goodchild 90] [Automated Mapping] facilitating the production of standard maps, [Map Analysis] providing measurement and overlay tools that are cheaper than traditional methods, [Inventory] giving geographic access capabilities to existing governmental and corporate databases, [Spatial Analysis & Spatial Decision Support] enabling new uses for old data by giving users query and analysis tools.

5. And one more [Iles89] A GIS is basically a tool that mines data and displays it. It doesn't clean it up, or maintain it, and seldom even looks to see if it's reasonable.

6. 第一部分 地理信息系统的数据工程

7. Spatial Data What is it!

8. Syracuse • Where is it? • How do we locate it in space? • Well, on earth, anyway

9. Basic Definition and explanation of Spatial Data (空间数据的基本定义与解释)

10. Spatial Data Spatial Analysis Information GIS = Geographic Information Sciences

11. GISystems, GIScience and GIStudies GISystems GIScience GIStudies

12. GISystems, GIScience and GIStudies • GISystems (GIS) • Emphasis on technology and tools • “GIServices” • Implements storehouse of GISci knowledge • GIScience (GISci) • Fundamental issues raised by the use of GIS and related technologies (e.g.) • Spatial analysis • Map projections • Accuracy • Scientific visualization • Systematic study of the use of geographic information • GIStudies (GISt?) • how systems and science are embedded in a societal context, applications

13. Geographic Information Science • The organized activity by which people measure aspects of geographic phenomena and processes. • Represent the measurements and operate upon these representations to discover new relationships.

14. Geographic Information Science • Organized activities and tools by which people make:Measurements, Representation, Operations and Transformations within Institutional, Social and Cultural Context (Chrisman, 2002)

15. Our Geographic Information Science • We will emphasize integration of data, technical and human resources within the framework of the information technology. • We will explore issues related to GIS future development (capability, interoperability, accessibility).

16. Personnel Software Hardware Spatial Data Entry Storage Manipulation Presentation Analysis

17. Maps and Plans Digital data Paper files Data GIS Data Photogrammetry Interviews Data Data Field survey Remote Sensing GIS Data Sources

18. Building Topography Land use Utility Soil Type Roads District Land Parcels Geography Objects

19. SPATIAL (GEOGRAPHY) DATA (OBJECTS) • spatial component • relative position between objects • coordinate system • attribute component • explains spatial objects characteristics • spatial relationship • relationship between objects • time component • temporal element

20. SPATIAL DATA SPATIALNON-SPATIAL ADDRESSNAME HAMID 9, JALAN JAYA JALAN JAYA 10, JALAN JAYA LUKE 9 10 MAP DATABASE

21. SPATIAL DATA CRITERIAS: • X-Y Coordinate System • Shape • Area/Size • Perimeter • Distance • Neighborhood

22. ATTRIBUTES: • Explains about spatial data • Relevant non-spatial data • Words or Numbers • Qualitative methods • Quantitative methods

23. GIS Charts Tables Tabular, GPS INTERNET DATA 数据处理过程 Digital data Digitize

24. Kinds of data • Geographic Where it is • Attribute What it is • Metadata Data about the data • documentation How it was made • data dictionary What do terms mean • What is a road, highway, expressway, thruway, …….? • What is a lake, pond, impoundment? • What are names, addresses ……?

25. Earth’s Coordinate System X is Longitude and is measured E and W from Greenwich, England. West is negative, East is positive Y is latitude and is measured N and S from the equator. North is positive and S is negative. These are called Geographic Coordinates

26. Spatial Reference Systems • The relationship between places creates the geometry and gets analytical geometry. Spatial measurements require geometric assumptions. Local measurements must be connected to a larger framework, otherwise they become obsolete.

27. Earth is NOT a sphere! • It is more pear shaped • To accommodate this geographers and surveyors have created models of the earth’s surface • These are called Datums

28. When using geographic data you must be sure that all the data is based on the same Datum • There are hundreds of datums worldwide • In the US the common ones are NAD 27 NAD 83 WGS 72 WGS 84

29. Location In order to place objects at a specific location, we need to define a coordinate system to represent the surface of the Earth. Consider the geographic grid system. North Vertical meridians Horizontal parallels Prime meridian at British Royal Observatory at Greenwich Equator South

30. Longitude and Latitude Longitude measures the angular distance from the prime meridian. East/West Latitude measures the angular distance from the equator. North/South Units: Degrees minutes seconds 12d 30m 15s Decimal degrees 12.5042 degrees

31. Oops! Can't flatten a Sphere Without distortion

32. Map Projection Geographic coordinates are based on a spherical model. However to represent maps on a 2D surface like on our computer screen or on a paper map, we need to rely upon a map projection, a mathematical formula that transforms latitude and longitude locations to x, y coordinates. For example: Moscow Geographic UTM latitude: 37d 36m 30s x: 412,648.41 meters longitude: 55d 45m 01s y: 6,179,073.07 meters

33. Many Different Projections Different projections suit different applications. For example, some projections preserve distance, while other preserve area, or shape, or direction. It is important to note that different datasets transformed to different projections will not register with one another. That’s where GIS can help a lot!

35. Stretch the top Stretch the bottom X, Y = Longitude, Latitude 90 60 30 Equator 0 -30 -60 -90 -180 -90 0 +90 +180 Lines of constant Longitude Lines of constant Latitude

36. -76.15° 43.04° W76.15° N43.04° X, Y = Longitude, Latitude 90E, 30N +90, +30 90 60 30 Equator 0 -30 -60 -90 -30 90W, 30S -90 -180 -90 0 +90 +180 Lines of constant Longitude Lines of constant Latitude

37. The world in Geographic Coordinates Is Antarctica Really that big?

38. TheProjectionProblem • There are many mathematical ways of projecting the spherical surface onto a flat surface. • For the earth these have names like Albers equal area Mercator Albers Peters Polyconic Lambert equal area Azimuthal

39. Mercator

42. Other Projections Which is right? Answer: All of them! They are just different!

43. All data must be in the same projection • (Unless you are working with a very small area)

44. Table of Contents shows 3 layers 2 Layers displayed – They match! All three match in space Question #2 Layers?

45. 空间数据的存储方式 • In GISs data is almost always stored in thematic layers – for example • Boundaries • Rivers • Roads • In ArcView, one kind of GIS, it looks like this Layers?

46. Map data in a GIS • Paper maps have many Themes orLayers • lakes, roads, streams, names, etc. • In a GIS we can separate themes • In fact, generally we MUST separate themes • So how is the theme data stored

47. Themes or Layers Geographic location (X,Y) Streams Power lines Landuse Roads

48. GIS map data • Most GISs store data in thematic layers. They can be called • Layersor • Coverages or • Shape files • Features are called features or objects • A mapcompositionis a combination of layers

49. GIS representation of the world In a GIS, different object types are represented by different layers or themes. A layer can either be points, lines, polygons, and possibly a raster dataset. Each layer is also associated with an attribute table.

50. Examples of layer types points lines polygons Retail Stores Highways Countries Cities,towns City Streets Postal Zones Manhole Covers Power Lines Tax Parcels Telephone Poles Rivers Census Blocks or Tracts Airports Water, Sewer Lines Airports Businesses Railroads Building Outlines Warehouses Shorelines Military Installations Customers Bus Routes Lakes Prospects Pipelines Area Code Boundaries Disease cases Runways Counties