Where2.0Now - Finding the heat in Thematic Maps
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Where2.0Now - Finding the heat in Thematic Maps



Thematic Mapping was once a specialist process for analysing statistical data spatially. GI Professionals understood how to do it, why they were doing and how to interpret the results. Thanks to the ...

Thematic Mapping was once a specialist process for analysing statistical data spatially. GI Professionals understood how to do it, why they were doing and how to interpret the results. Thanks to the proliferation of API’s from the Web 2.0 world, Thematic Mapping API’s have become readily available and accessible by any developer with basic technical know how. You don’t have to be a GI Professional to create an impressive looking Thematic Map of your data. This presentation attempts to discuss how increased accessibility to geospatial processes is a good thing, BUT, you need to understand the underlying principles of geospatial analysis if you are going to leverage this technology



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Where2.0Now - Finding the heat in Thematic Maps Where2.0Now - Finding the heat in Thematic Maps Presentation Transcript

  • Where2.0Now - Finding the heat in Thematic Maps John Fagan Program Manager, Microsoft
  • 1990’s – Sean Phelan’s vision
  • 1996 - Multimap.com launched (no maps)
  • Desktop GIS - MapInfo Desktop for Power Mac v4
  • 1997 - Multimap GeoStack MapInfo Desktop for power mac Hacked to make it serve maps over http Collins Bartholomew Raster maps Multimap.com gif.cgi Mapping API +Caching engine MySQL Bartholomew & OS Gazetteer places.cgi cache miss
  • MapInfo for Power Mac v4 Features
    • Local & Remote Data Access
      • Directly read dBase, Lotus 1-2-3, Microsoft Excel, delimited ASCII in native formats
    • Geocoding
      • Create points
      • Geocode to street address, ZIPcodes, census tract, user-definedmatch options
    • Map Creation and Editing
      • Raster map registration and display .GIF, .JPEG, .TIFF, .PCX, .BMP, .TGA, .BIL
      • Graphics Import
      • DXF
      • Digitizing to create vector images; supports digitizers
      • Autoscrolling to create or edit objects larger than the current window
      • Autotracing of existing object with mouse or digitizer
      • Clone Mapping to copy current map window
      • Customize map objects (fill patterns, line types, symbols, True Type fonts)
      • Map Editing Functions: Reshape objects, snap to editing, move objects, select multiple nodes for deletion, overlay nodes, copy objects, create polylines from regions, create regions from polylines, smooth / unsmooth, revert table, clear map objects only
    • Data Visualization
      • Create thematic maps using ranged shading, bar charts, pie charts, dot densities, graduated symbol and individual values
      • Range classification of maps based on equal count, equal ranges, inflection point, natural breaks, standard deviation, quantile, user defined
      • Combine thematic options to create maps that display multiple variables from many tables
      • Thematic joins based on: Count, sum, value, average, min/max, weighted average, proportional sum, proportional average, proportional weighted average
      • Attach data to any object
      • Multiple views Dynamically linked "hot" views of map, row & column, graph Page layout view District management browser/window display Legend window
      • Summary statistics window MapBasic command window Set layer display zoom
      • Zoom range 55 ft. to 100,000 miles Set layer display order View hundreds of layers Seamless map layers
      • Escape from map redraw
      • 18 projections available On the fly transformation/display Overlay different projections Convert between projections
    • Analysis Capabilities
      • Get information about any object
      • Donut/island polygons supported
      • Polygon Overlay Operations Data aggregation / disaggregation, erase, erase outside, split, combine, overlay nodes
      • Buffers: Create buffers around any object or group of objects--points, lines, polylines, polygons
      • Geographic Selection
        • Find any object
        • Points within radius/polygon Lines/polylines within radius/polygon Polygons within radius/polygon
      • SQL/Advanced Querying Language Query based on expressions, perform aggregations, display derived fields, perform subqueries, do multi-table joins and perform geographic joins
      • Relational query operators
        • Standard and Geographic operators
        • Contain, contains entirely, within, entirely within, intersection/union
  • MapInfo for Power Mac v4 Features
    • Functions
      • Day, month, year, current date or weekday functions.
      • Change strings to upper, lower or proper case.
      • Find sin, cos, arcsin, arccos, sum, average, min, max, absolute value, exponential or rounded. · Find area, perimeter, length, and determine x/y centroid.
      • String functions
      • Conversion functions. Results can be treated as a separate table and saved as a separate database.
      • Aggregate functions from SQL queries
      • Group or sort data based on any field or expression. Sum, min, max, average, weighted average or count.
    • Statistics
      • Show count, total, mean, standard deviation, variance, range, min and max of a group of values.
      • Dynamically display sum and average of a selection.
    • Database Management
      • Create and change width or type of field, add/delete fields, index any field. Field types supported: character, floating point, integer, decimal, logical, date. Number of records limited only by hard disk storage; up to 250 fields per record.
    • Display and Presentation
      • Map Clipping to highlight region
      • Automatic or manual labeling
      • Label position by anchor point, offset distance, callouts
      • Text styles: bold, italic, underline, all caps, halo, boxed, shadow, double wide
      • True type fonts and text rotation
      • Hundreds of symbols and user created bitmaps
      • Unlimited number of colors
      • Scalable labels when zooming
    • Output
      • Print individual windows or layout
      • Printers/plotters: Supports any Windows compatible printer or plotter. Requires Windows-compatible driver included with Windows or from third-party vendor.
      • Output to Bitmap (.BMP) or Windows Metafile (.WMF)
  • Why should maps be for GIS Professionals only?
  • gif.cgi? pc=ec4a2dy
  • gif.cgi? pclist= ec4a2dy,ec1n2ns
  • gif.cgi?pclist= ec4a2dy,ec1n2ns& width=500&height=500
  • gif.cgi?pclist= ec4a2dy,ec1n2ns&width=500&height=500& ds=1
  • Multimap.com vs MapInfo
    • gif.cgi
    • simple, but scalable and accessible to all
  • Many customers still use gif.cgi today
  • >> Fast forward a few years
  • Visualisation – Heat Maps
      • Value interpolation
      • Frequency based
    http://idvux.spaces.live.com/blog/cns!2EB6AAF6C3AC1EBE!1932.entry Heat is interpolated because it is a continuous data type.  If it is 100 degrees at one station and 50 degrees at a neighboring station, it must be 75 degrees somewhere between the two. Heat brightness on the surface illustrates the frequency of crime reports
  • Choropleth map
  • Thematic Mapping API’s
  • Again, the web developers have come to the rescue and made GIS functionality accessible to all http://www.programmableweb.com/tag/thematic
  • Wait.... Do we want web developers to carry out spatial analysis?
  • ....it could go wrong
    • Current API’s not fit for serious choropleth thematic analysis
    • Will result in committing wrong resources to the wrong problems in the wrong places
    • Need to understand underlying methods and limitations thereof
    • Need access to underlying data
  • Stan Openshaw and MAUP
    • The modifiable areal unit problem (MAUP) is a source of statistical bias that can radically affect the results of statistical hypothesis tests.
    • MAUP occurs when point-based measures of spatial phenomena (e.g., population density) are aggregated into districts , the resulting summary values (e.g., totals, rates, proportions) are influenced by the choice of district boundaries.
    • The issue was discovered in 1934. The term MAUP was first coined and described in detail by Openshaw (1984), who lamented that "the areal units (zonal objects) used in many geographical studies are arbitrary, modifiable, and subject to the whims and fancies of whoever is doing, or did, the aggregating. " (Openshaw, 1984, p.3).
    • The problem is especially crucial when the aggregate data are used for cluster analysis for spatial epidemiology, spatial statistics or choropleth mapping, in which misinterpretations can easily be made without realizing it.
  • What if John Snow used todays API’s?
  • http://www.programmableweb.com/tag/thematic
  • One solution to Stan’s MAUP
    • Define your own areas by aggregating existing areas
      • Grab some admin areas that are small and uniform (with respect to attributes)
      • Enumeration Districts could work in UK
    Haining (1990)
  • Aggregate areal units
    • Classify areal units based on cluster analysis using a large number of common variables related to the analysis you are carrying out
    • Deprivation indexes are often used for Epidemiology analysis
    • UK Deprivation indexes and associated variables
  • GIS could get this right in 1996
  • Bing Maps/SQL Server 2008
  • Aggregate areal units using STUnion ()
    • DECLARE @geom1 geometry
    • DECLARE @geom2 geometry
    • SELECT @geom1 = (SELECT GeomCol1 FROM FeatureTest WHERE blah)
    • SELECT @geom2 = (SELECT GeomCol1 FROM FeatureTest WHERE blah)
    • SELECT @geom1.STUnion(@geom2)
    Union (here: Multipolygon)
  • View Choropleth overlays using Silverlight
  • Thematic Maps as Vector Data
  • Thanks john fagan ubergeo.com @johnbfagan