Lesson 9

Visualising and Analysing

Geographical Data

ISSS608 Visual Analytics and Applications

Content

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Introducing map
  • Properties of geographical data
  • Typology of map
  • Thematic mapping techniques
  • Alternative mapping techniques

What is a geographical dataset?

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Provides geographical location.

  • Can be encoded explicitly in the dataset or need to be geocoded using location ID.

With explicit coordinates

Without explicit coordinates

Role of a map

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • A map serves as a record.

Role of a map

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • A map reveals spatial patterns.

Role of a map

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • A map represents geographical data.

Role of a map

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • An interface between geospatial data users and geospatial data.

Properties of Geographical Data

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Geospatial data models

  • Geographical reference

  • Geocoding

Properties of Geographical Data

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Geospatial data models

  • Geographical reference

  • Geocoding

Properties of Geographical Data

Geospatial data models

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Vector – implementation of discrete object conceptual model

    –Point, line and polygon representations

    –Widely used in cartography, and network analysis

  • Raster – implementation of field conceptual model

    –Array of cells used to represent objects

    –Useful as background maps and for spatial analysis

     

Properties of Geographical Data

Vector Data Models

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

Properties of Geographical Data

Vector data models

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

Text

  • Real world features and their spatial representations

Properties of Geographical Data

Georelational Vector Data Model

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Stores spatial and attribute data separately in a split system: spatial data (”geo”) in graphic fields and attribute data (“relational”) in a relational database

Properties of Geographical Data

Georelational Vector Data Model

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Simple vector data model: Shapefile

Properties of Geographical Data

Raster Data Models

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • All raster formats are basically the same

    –Cells organized in a matrix of rows and columns

    –Content is more important than format: data or picture?

Properties of Geographical Data

Raster Data Models

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Google map

Properties of Geographical Data

Source of Digital Data

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Singapore

Properties of Geographical Data

Source of Digital Data

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • International

Properties of Geographical Data

Georeferencing

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Georeferencing means that the internal coordinate system of a map or aerial photo image can be related to a ground system of geographic coordinates.
  • Two major families of georeferencing systems:
    • Geographic Coordinates Systems
    • Projected Coordinates Systems

Properties of Geographical Data

Georeferencing

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Geographic Coordinates Systems define locations on the earth using a three-dimensional spherical surface, for example, WGS84.

Properties of Geographical Data

Map Coordinates

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Commonly used geographic coordinates systems.

Properties of Geographical Data

Map Coordinates

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Projected coordinates systems: Any method of representing the surface of a sphere or other shape on a plane, for example, Mercator.

Properties of Geographical Data

Map Coordinates

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Two commonly used projection coordinates systems of Singapore.

Properties of Geographical Data

Map Coordinates

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Spatial referencing directory

Properties of Geographical Data

Map Coordinates

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • GDAL: gdaltransform, open source tool for transforming geospatial data from one projection to another projection.

Properties of Geographical Data

Geocoding

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Geocoding is the process of transforming a description of a location - such as a pair of coordinates, an address, or a name of a place - to a location on the earth's surface.

Properties of Geographical Data

Geocoding

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Creating geospatial-enabled data in Singapore

Properties of Geographical Data

Geocoding

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Structure of SLA's Address point Data

Properties of Geographical Data

Geocoding

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • SLA's Address point Data API

Properties of Geographical Data

Geocoding

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Some useful tips on using SLA's geocoding API.

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

Typology of Maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

Typology of Maps

Reference Maps

  • Topography map

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

Typology of Maps

Thematic Maps

Qualitative

Quantitative

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Visual variables and cartographic symbols

Thematic Mapping

Qualitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Point symbol map

Thematic Mapping

Qualitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Line symbol map

Thematic Mapping

Qualitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Area or polygon symbol map

Thematic Mapping

Qualitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Multivariate symbol map, Chernoff Faces

Thematic Mapping

Qualitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Visual Variables and Cartographic Symbols

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Proportional symbol map
    • use different symbol size to represent attribute values

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Proportional symbol map: Pie chart map
    • use statistical chart to represent attribute values

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Proportional symbol map: Bricks map

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Dot Density Map
    • use point of similar size to represent attribute values.

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Chrolopleth map (area shading)
    • Use different colours or patterns intensity to represent attributes values

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • A un-classed choropleth map

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • A classed choropleth map

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Bivariate choropleth map

    • Symbolized features based on more than one attribute

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Bivariate choropleth map

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Cartogram

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Cartogram of the world's languages

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Cartogram in R

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

Hexagon Binning Map

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

Hexagon Binning Map using Tableau

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

Bivariate Hexbin Map

Thematic Mapping

Quantitative maps

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Choose number of classes

  • Data classification methods

Quantitative Mapping Considerations

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Sturges’ formula

 

 

 

 

  • Number of intervals?
    • Not less than 4
  • To avoid an overly generalized map
    • Not more than 12 colors
    • 7 or 8 shades of the same color

Quantitative Mapping Considerations

Choose appropriate number of classes

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Equal Interval method divides the range of attribute values into equally sized classes.

Quantitative Mapping Considerations

Data Classification Methods

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Equal Count method assigns same number of features per class.

Quantitative Mapping Considerations

Data Classification Methods

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Natural breaks method using Default Jenk’s statistical optimization to find natural groupings in the data

Quantitative Mapping Considerations

Data Classification Methods

ISSS608 Visual Analytics and Applications

Lesson 9: Visualising and Analysing Geographical Data

  • Standard deviation method, a measure of dispersion

Quantitative Mapping Considerations

Data Classification Methods

IS428 Visual Analytics for Business Intelligence

Lesson 9: Visualising and Analysing Geographical Data

  • Colour brewer

Quantitative Mapping Considerations

Colour selection

IS428 Visual Analytics for Business Intelligence

Lesson 9: Visualising and Analysing Geographical Data

  • Isopleth Map

Quantitative Mapping

IS428 Visual Analytics for Business Intelligence

Lesson 9: Visualising and Analysing Geographical Data

  • Lines of equal value are drawn such that all values on one side are higher than the "isoline" value and all values on the other side are lower, or

  • Ranges of similar value are filled with similar colours or patterns.

Quantitative Mapping

IS428 Visual Analytics for Business Intelligence

Lesson 9: Visualising and Analysing Geographical Data

Contour Map in ggmap of R

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