Geographic Coordinates GIS 1 Geographic Coordinate System Spherical

Geographic Coordinates GIS 1

Geographic Coordinate System • Spherical coordinates based on angles of rotation of a radius anchored at earth’s center • Latitude and longitude • Used by many world and federal agencies (e. g. U. S. Census Bureau) GIS 2

Lat/Long coordinates Degrees, minutes, and seconds (DMS): • 40° 26′ 2″ N latitude • 80° 0′ 58″ W longitude Decimal degrees (DD) • 1 degree = 60 minutes, • 1 minute = 60 seconds • 40° 26′ 2″ = • 40 + 26/60 + 2/3600 = • 40 +. 43333 +. 00055 = • 40. 434° GIS 3

Lat/long coordinates Translated to distance • 1° = 24, 859. 82 / 360 = 69. 1 miles • 1′ = 24, 859. 82 / (360 * 60) = 1. 15 miles • 1″ = 24, 859. 82 * 5, 280 / (360 * 3, 600) = 101 feet World circumference through the poles is 24, 859. 82 miles Length of the equator is 24, 901. 55 miles GIS 4

Longitude lines 0 ° Longitude (prime meridian) GIS 5

Prime Meridian (Greenwich England) GIS 6

Latitude lines 0 ° Latitude (equator) GIS 7

Latitude and longitude Coordinates Pittsburgh, PA USA 40 -80 GIS 8

Map Projections GIS 9

Map projections • Way to represent the curved surface of the Earth on the flat surface of a map • Each map projection has advantages and disadvantages • depends on the scale of the map • purposes for which it will be used • some projections are good for -small areas -areas with a large east-west extent -areas with a large north-south extent GIS 10

Map projections Planar Cylindrical Conic http: //www. nationalatlas. gov/articles/mapping/a_projections. html#two GIS 11

Conformal projection • Cylindrical projection • Parallels and meridians at right angles • Preserves angles and shapes of small objects • Distorts the size/shape/area of large objects • Seldom used for world maps Example: Mercator projection (1569) GIS 12

Equivalent Projection • Conic projection • Preserves accurate area • Scale and shape are not preserved • Standard projection for U. S. Geological Survey, U. S. Census Bureau Example: Albers Equal Area GIS 13

Compromise Projections • Good for viewing entire world • Neither equivalent nor conformal • Meridians curve gently • Doesn’t preserve properties, but “looks right” • Used by Rand Mc. Nally and the National Geographic Society Example: Robinson projection (1961) GIS 14

When projection is important • Small-scale maps -Comparing shapes, areas, distances, or directions of map features -Natural appearance desired New York Los Angeles Projection: Mercator Distance: 3, 124. 67 miles New York Los Angeles Projection: Albers equal area Distance: 2, 455. 03 miles Actual distance: 2, 451 miles GIS 15

When projection is not important • Many business, policy, and management applications -Concerned with the relative location of different features • On large scale maps -Error is negligible GIS 16

Rectangular Coordinate Systems GIS 17

Rectangular coordinate systems UTM (U. S. military) State Plane (local U. S. governments) • Cartesian coordinates (x, y) GIS 18

Universal Transverse Mercator (UTM) • Developed by U. S. Army Corps of Engineers (1940 s) • Covers world, 80°S to 80°N • Metric coordinates • Not a single projection but 60 tuned Transverse Mercator projections GIS 19

State Plane Coordinate System • Established by the U. S. Coast and Geodetic Survey in 1930 s • Used by local U. S. governments • Rectangular coordinates (all positive coordinates in feet or meters) • Originally North American Datum (NAD 1927) • More recently NAD 1983 and 1983 HARN GIS 20

State Plane zones • 125 zones -At least one for each state -Cannot have zones joined to make larger regions -Follow state and county boundaries • Each zone has its own, tuned projection -Lambert conformal projection for zones with east-west orientation -Transverse Mercator projection for zones with north-south orientation GIS 21

State Plane zones GIS 22

Pittsburgh Neighborhoods as State Plane Coordinates • 1983, Pennsylvania South, Feet GIS 23

Arc. GIS projection tip • GIS map layers in different projections have different coordinate systems and thus will not overlay each other unless they have spatial reference data in a. prj file • Assign projections according to the agency U. S. Census Files • • • Federal agency Block groups Geographic coordinate system City of Pittsburgh • • • Local planning agency Sidewalks State plane coordinate system GIS 24

Arc. GIS projection tip • The first layer added in Arc. Map sets the “map projection” • Additional layers will overlay properly as long as the correct. prj file is included • Example: Sidewalks added first (state plane), block groups match even though they are geographic coordinate system (gcs) projection GIS 25

GIS Data Sets GIS 26

GIS Data Sets • Arc. Info Coverages • Arc. View Shapefiles • Annotation Layers • CAD Files • Aerial Photos Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 27

Arc. GIS • Integrated collection of GIS software products • Arc. GIS framework deploys GIS functionality and business logic wherever it is needed—in desktops, servers (including the Web), or mobile devices. -Desktop GIS (Arc. View, Arc. Info, Arc. Reader, Arc. Editor, Arc. GIS Extensions, Arc. Explorer) -Server GIS (Arc. IMS, Arc. GIS Server) -Mobile GIS (Arc. PAD) Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 28

Arc. Info GIS 29

Arc. Info Coverages AAT ARC BND CNT PAL PAT TIC DBF Arc Attribute Table Arc coordinates and topology Coverage minimum and maximum coordinates Polygon centroid table Polygon topology Polygon/Point Attribute Table Tic coordinates and Ids Database Table GIS 30

Arc. Info Coverages • Advantages -Many feature types • Disadvantages -Cannot edit in Arc. Map Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 31

Coverage Attribute Table • Polygon Coverage Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 32

Coverage Attribute Table • Point Coverage Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 33

Coverage Attribute Table • Line Coverages Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 34

Arc. Info Export files • . e 00 export exchange file • Arc. Toolbox translates into Arc. GIS • Creates Coverages Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 35

Arc. View Shape Files Advantages • heads-up digitizing and editing • less storage/rapid display • can convert from Arc. Info coverage and back • can export to CAD Disadvantages • one feature type • no area or perimeter Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 36

Arc. View Shape Files From 3 to 5 Files • . shp - stores feature geometry • . shx - stores index of features • . dbf - stores attribute data • . sbn and. sbx - store additional indices Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 37

Arc. View Shapefiles Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 38

Annotation Layers Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 39

Annotation Layers • • Separate independent layers Can be turned on/off Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 40

CAD Files Why CAD Drawings? • Better Precision for Digitizing -Auto. CAD -Microstation Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 41

Aerial Photos Combining Grid and Vector Maps Copyright – Kristen S. Kurland, Carnegie Mellon University GIS 42

XY Event Tables GIS 43

XY Data (Event Files) Data table that includes map coordinates, such as latitude and longitude or projected coordinates GIS 44

Event Files GIS 45

Exporting Event Files GIS 46

GIS Data Sources GIS 47

Common Sources • U. S. Census Bureau • Geospatial One Stop • U. S. Geological Survey • Esri • Historic websites • Colleges and universities • International sites • State agencies • Local agencies or engineering firms GIS 48

U. S. Census TIGER/Line® Files http: //www. census. gov/geo/www/tiger/ Topologically Integrated Geographic Encoding and Referencing files -Census Bureau’s product for digital mapping of the U. S. -TIGER maps are available for the entire U. S. and its possessions GIS 49

Census TIGER/Line® Files GIS 50

State Census Tracts (2000) County sub-divisions Between 1, 000 and 8, 000 people or 1, 700 housing units and 4, 000 people Homogeneous population characteristics (e. g. economic and living) Normally follow visible features May follow government boundaries or other non-visible features GIS 51

County Census Tracts (2000) GIS 52

City Census Tracts (2000) GIS 53

Census Block Groups (2000) Census tract sub-divisions 400 housing units, with a minimum of 250 and maximum of 550 Follow visible features such as roads, rivers, and railroads GIS 54

Census Blocks (2000) Smallest geographic area for which the U. S. Census Bureau collects and tabulates decennial census information Block boundaries are visible (street, road, stream, shoreline, etc) or nonvisible (county or city limits, property lines, etc. ) GIS 55

U. S. Census data tables American Fact. Finder GIS 56

http: //factfinder. census. gov/ GIS 57

2000 Summary File Tables Summary File 1 (SF 1) Short form, entire population • Population • Age • Sex • Race • Families • Households • Housing units Tracts, block groups, blocks Summary File 3 (SF 3) Long form, 1 in 6 households, randomly • Income, poverty • Educational attainment • Citizenship • Employment, workplace, disability • Transportation, travel time to work • Detailed housing attributes, housing value, residency 5 years previous • Languages spoken, ancestry Tracts, block groups GIS 58

http: //factfinder 2. census. gov/main. html GIS 59

2010 Data Release Schedule http: //www. census. gov/population/www/cen 2010/glance/ GIS 60

Data Ferret http: //dataferrett. census. gov/ GIS 61

Spatial data infrastructure • Federal Geographic Data Committee -Established by presidential order -Responsible for standards, policies, web portals -Geospatial One Stop, http: //gos 2. geodata. gov Base maps and spatial data produced by governments for the public good Non-rivalrous and non-excludable consumption Widely-used structures needed for society and enterprises to function GIS 62

Physical features: U. S. Geological Survey • National Map Orthoimagery, replacing the Digital Orthophoto Quadrangles -High-resolution, seamless images in UTM coordinates -Rectified to remove distortions -1 m resolution with 0. 5 m or 1 ft in urban areas, natural color GIS 63

Physical features: U. S. Geological Survey • National Elevation Data set (NED) -Replaces the Digital Elevation Model (DEM) -Seamless raster map with 30 m resolution for nation and 10 m or better in some areas Hillshade NED map for Rockville, MD GIS 64

Physical features: U. S. Geological Survey • Land cover -Natural and manmade surface features -Collected from satellites in 1992, 2001 GIS 65

Physical features: U. S. Geological Survey • National Map Hydography Dataset (NHD) -Water bodies, lines, and points -Identifies segments (reaches) with network coding (flow and direction) GIS 66

ESRI’s Website http: //www. esri. com/data/resources/geographic-data. html GIS 67

National Historic GIS http: //www. nhgis. org/ GIS 68

University websites • Penn State’s PASDA GIS 69

International sites Rwanda Ministry of Health GIS 70

International sites USAID/PEPAR GIS 71

State agencies Texas Department of State Health • http: //www. dshs. state. tx. us/chs/ GIS 72

Local agencies • Engineering Companies -land surveys, aerial photos, CAD drawings • Government agencies -Adelaide Australia Tip: search by “Adelaide Planning Department) -Austin, TX Tip: Search by county name (Travis, County Texas) ftp: //ftp. ci. austin. tx. us/GIS-Data/Regional/coa_gis. html GIS 73

Local agencies GIS 74