Mapping Your Data 1


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The first presentation for the mapping your data workshop. Much more informative, but not nearly as hands on. From an informational standpoint its better then 2, but from a workshop stand point it\'s much worse.

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  • Mapping Your Data 1

    1. 1. Mapping Your Data Christopher Martin [email_address]
    2. 2. Data Models <ul><li>Two primary data models used when making maps </li></ul><ul><ul><li>Raster Data </li></ul></ul><ul><ul><li>Vector Data </li></ul></ul>
    3. 3. Raster Data <ul><li>Consists of discrete cells (think graph paper) </li></ul><ul><ul><li>Each cell has a discrete value </li></ul></ul><ul><ul><li>Occur in rows and columns </li></ul></ul><ul><li>Examples </li></ul><ul><ul><li>Images (all image types) </li></ul></ul><ul><ul><li>DEM </li></ul></ul>
    4. 4. Vector Data <ul><li>Each position is represented by coordinates </li></ul><ul><li>Coordinates are connected to form lines or polygons </li></ul><ul><li>Points, lines and polygons are then used to represent geographic features </li></ul><ul><li>Examples </li></ul><ul><ul><li>Shapefile </li></ul></ul>
    5. 5. Points, Lines, Polygons
    6. 6. Data Sources <ul><li>US Census Bureau </li></ul><ul><ul><li>Not just population data </li></ul></ul><ul><ul><li>Generalized Boundary Data </li></ul></ul><ul><li>ESRI </li></ul><ul><ul><li>TIGER/LINE </li></ul></ul><ul><ul><li>NED Data </li></ul></ul><ul><ul><li>FEMA Q3 Flood Data </li></ul></ul><ul><li>USGS </li></ul><ul><ul><li>SEAMLESS Distribution </li></ul></ul>
    7. 7. Data Sources (cont’d) <ul><li>NYS GIS Clearing House </li></ul><ul><ul><li>Membership required </li></ul></ul><ul><ul><li>Wide variety of data </li></ul></ul><ul><li>CUGIR </li></ul><ul><ul><li>NYS and National data </li></ul></ul><ul><ul><li>Free, huge variety </li></ul></ul><ul><li>CIGAR </li></ul><ul><ul><li>Worldwide Elevation Data </li></ul></ul><ul><li>Columbia University EDS </li></ul><ul><ul><li>Electronic Data Service </li></ul></ul>
    8. 8. Data Sources (cont’d) <ul><li>Geography Network </li></ul><ul><ul><li>Aggregates data from different providers </li></ul></ul><ul><ul><li>Online Map Server Available </li></ul></ul>
    9. 9. Data Quality <ul><li>Meta Data </li></ul><ul><ul><li>Data about the data </li></ul></ul><ul><ul><li>All legitimate providers will provide this </li></ul></ul><ul><ul><li>Available for download or online viewing </li></ul></ul>
    10. 10. Map Scale <ul><li>The ratio between the distance on the map, and the distance in real life </li></ul><ul><ul><li>ALWAYS expressed in terms of 1 </li></ul></ul><ul><ul><li>Usually a ratio </li></ul></ul><ul><ul><ul><li>E.g. 1:100000, 1:10000 </li></ul></ul></ul><ul><ul><li>Other scales are available </li></ul></ul><ul><ul><ul><li>Visual scale is the second most common </li></ul></ul></ul>
    11. 11. Coordinate Systems <ul><li>Two types of coordinate systems used in geography </li></ul><ul><ul><li>Spherical (Latitude and Longitude) </li></ul></ul><ul><ul><ul><li>Typically not used in ArcGIS </li></ul></ul></ul><ul><ul><ul><li>Always used in Google Earth </li></ul></ul></ul><ul><ul><li>Rectangular </li></ul></ul><ul><ul><ul><li>Predominantly used in Arc and GIS in general </li></ul></ul></ul><ul><ul><ul><li>UTM - Universal Transverse Mercator </li></ul></ul></ul><ul><ul><ul><li>State Plane </li></ul></ul></ul><ul><ul><ul><li>Other countries have their own. </li></ul></ul></ul>
    12. 12. Spherical Coordinate System <ul><li>Based on meridians and parallels </li></ul><ul><li>Latitude (parallels) </li></ul><ul><ul><li>Measured northward or southward from the equator to poles </li></ul></ul><ul><ul><li>Ranging 0-90 0 north or south </li></ul></ul><ul><ul><li>The measuring units are degrees, minutes, and seconds, 1 0 = 60’ and 1’=60” </li></ul></ul><ul><ul><li>The length of one degree latitude is similar everywhere, ≈ 111km/69miles </li></ul></ul><ul><li>Longitude (meridians) </li></ul><ul><ul><li>Measured eastward or westward from the Prime Meridian at Greenwich, England to the International Date Line </li></ul></ul><ul><ul><li>Ranging 0-180 0 east or west </li></ul></ul><ul><ul><li>The measuring units are the same as Latitude </li></ul></ul><ul><ul><li>Length of one degree longitude reduces toward poles </li></ul></ul>
    13. 13. Rectangular Coordinate Systems <ul><li>Convert the curved surface of the earth onto a flat surface </li></ul><ul><li>Standard cartesian coordinates, but different names </li></ul><ul><ul><li>X is called “Easting” </li></ul></ul><ul><ul><li>Y is called “northing” </li></ul></ul>
    14. 14. Universal Transverse Mercator <ul><li>Based on the mercator map projection </li></ul><ul><li>Divides the world into 60 zones </li></ul><ul><ul><li>Starts at 180 degrees longitude </li></ul></ul><ul><ul><li>Each zone is 6 degrees of longitude wide </li></ul></ul><ul><ul><li>Labeled 1-60 going eastward </li></ul></ul><ul><li>And 20 Rows </li></ul><ul><ul><li>Labeled C-X, skipping I and O </li></ul></ul><ul><li>Intersection of Row and Zone is a Quadrangle </li></ul><ul><ul><li>Usually referred to as “quad” </li></ul></ul><ul><li>Measurement unit is meters </li></ul>
    15. 15. Universal Transverse Mercator
    16. 16. State Plane <ul><li>Used exclusively in the United States </li></ul><ul><li>The US is divided into 120 zones </li></ul><ul><ul><li>Follow state and county lines </li></ul></ul><ul><li>Each state has its own map projection </li></ul><ul><ul><li>North to South states use Mercator </li></ul></ul><ul><ul><li>East to West states use Lambert Conformal Conic </li></ul></ul>
    17. 17. State Plane
    18. 18. So What?
    19. 19. Map Projections <ul><li>A way to convert coordinates from spherical (earth) to flat (map) </li></ul><ul><ul><li>Projections define how to to transform the spherical coordinates to flat ones </li></ul></ul><ul><ul><li>They are NOT map coordinates </li></ul></ul><ul><li>Classified two ways </li></ul><ul><ul><li>By the surface projected onto </li></ul></ul><ul><ul><li>By what gets distorted </li></ul></ul>
    20. 20. Surfaces <ul><li>Developable Surfaces </li></ul><ul><ul><li>What kind of shape will we use? </li></ul></ul><ul><ul><li>It has to be 2D, and we need to be able to “unroll” it </li></ul></ul><ul><ul><li>The earth gets “wrapped” in the shape, and the surface is transferred to the 2D shape </li></ul></ul><ul><li>Types </li></ul><ul><ul><li>Cylindrical, Conic, Azimuthal </li></ul></ul>
    21. 21. Cylindrical Projections <ul><li>Mercator </li></ul><ul><li>Transverse Mercator </li></ul>
    22. 22. Azimuthal Projections <ul><li>Top down view </li></ul><ul><ul><li>Or Bottom Up </li></ul></ul>
    23. 23. Conic Projections <ul><li>Used to focus on a particular continent </li></ul><ul><ul><li>Least amount of distortion for east-west direction </li></ul></ul>
    24. 24. Distortion Projections <ul><li>All maps distort </li></ul><ul><ul><li>It’s inevitable </li></ul></ul><ul><li>Projections can be grouped based on WHAT is distorted </li></ul><ul><ul><li>Conformal - shapes are the same </li></ul></ul><ul><ul><li>Equal-Area - areas are the same </li></ul></ul><ul><ul><li>Equidistant - distances are the same* </li></ul></ul>
    25. 25. Projection Example
    26. 26. Measuring Distortion
    27. 27. Comparisons of Projections <ul><li>Map Projection Poster </li></ul>
    28. 28. Map Types <ul><li>Thematic Maps </li></ul><ul><ul><li>Not reference maps </li></ul></ul><ul><li>Four main types </li></ul><ul><ul><li>Choropleth Map </li></ul></ul><ul><ul><li>Proportional Map </li></ul></ul><ul><ul><li>Isarithmic Map (contour) </li></ul></ul><ul><ul><li>Dot Map </li></ul></ul>
    29. 29. Choropleth Map <ul><li>Shaded Areas </li></ul><ul><ul><li>The “color” of the shade varies based on measurement of our variable </li></ul></ul>
    30. 30. Isarithmic Map <ul><li>Also known as Contour Maps </li></ul><ul><ul><li>We draw lines to connect separate variables that have the same value </li></ul></ul>
    31. 31. Proportional Symbol Map <ul><li>Uses symbols </li></ul><ul><ul><li>The size of the symbol varies according to the variable </li></ul></ul>
    32. 32. Dot Density Map <ul><li>Uses dots </li></ul><ul><ul><li>Size is uniform, but the concentration represents changes in the variable </li></ul></ul>
    33. 33. Cartograms <ul><li>Are NOT maps </li></ul><ul><ul><li>Area is not preserved </li></ul></ul><ul><ul><li>Area of the geographic regions varies by variable </li></ul></ul><ul><li>Two primary types </li></ul><ul><ul><li>Area </li></ul></ul><ul><ul><ul><li>Area gets larger or smaller depending on the variable </li></ul></ul></ul><ul><ul><li>Distance </li></ul></ul><ul><ul><ul><li>Nodes or places can be closer or farther depending on realtive distance </li></ul></ul></ul>
    34. 34. Cartogram
    35. 35. File Formats <ul><li>Shapefile </li></ul><ul><ul><li>A collection of points, lines and polygons </li></ul></ul><ul><ul><li>Tabular data values assocated with each </li></ul></ul><ul><li>DEM </li></ul><ul><ul><li>Raster data, each cell represents elevation </li></ul></ul><ul><ul><li>Comes in different resolutions </li></ul></ul>
    36. 36. Getting to Know ArcGIS <ul><li>ArcMap </li></ul><ul><ul><li>Your main tool. Handles map layout, projection, data classification, analysis </li></ul></ul><ul><li>ArcCatalog </li></ul><ul><ul><li>Asset management program. Maps drives of data for easy access, displays meta data, manages database connections </li></ul></ul><ul><li>ArcView </li></ul><ul><ul><li>Older version of ArcMap. </li></ul></ul><ul><li>ArcScene </li></ul><ul><ul><li>3D rendering </li></ul></ul>
    37. 37. Your friend, the Shapefile <ul><li>A Misnomer </li></ul><ul><ul><li>More the one file </li></ul></ul><ul><ul><ul><li>Vectors in one file </li></ul></ul></ul><ul><ul><ul><li>Data in another </li></ul></ul></ul><ul><ul><ul><li>Index in another </li></ul></ul></ul><ul><ul><ul><li>Optionally a projection file </li></ul></ul></ul>