Proportional Symbol Mapping

1
Proportional Symbol Mapping
2
Proportional SymbolsSome General Informaiton

• Also called graduated symbols
• Useful for for any data representing magnitude,
  that includes totals, ratios, proportions etc.
• mostly raw-count data are represented
• complement to choropleth maps, emphasize relative
  values

3
Spatial Analysis Process (review)

• Spatial question
• Spatially related data
• Characteristics of data
• Spatial Visualization
• Analysis and results
• Use (i.e., decision-making greater understanding
  of phenomena etc.)

4
What is proportional symbol mapping?

• Used to represent numerical data associated with
  point location (Slocum,1999)
• True point data-measuring actual locational
  information (example number of employees of Beko
  in Belikdüzu) Conceptual point data-point for
  summarization of area data (example number of
  employees in Büyükçekmece)
• Standardization can also be applied (example
  murders per 1000 people)

5
True Point and Conceptual Data

• True point means that data was collected at an
  exact location
• Conceptual means that it is summarized
• Not always easy to tell the difference (i.e.,
  population for a city)

6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
Standardizaiton Point Data

• Taking raw values and dividing by another value
• Examples accidents by location (raw)accident by
  1000 vehicles per day (standardized)

10
Making a proportional symbol

• 1. Choose a symbol
• mimetic or geometric
• Which geometric shape?
• 2D or 3D symbols
• 2. Choose method to scale symbols

11
Choose a symbol

• mimetic symbols
• mirror the mapped
• phenomenon
• eye-catching
• easy to read
• geometric symbols
• based on geometric
• shape
• e.g. circle, square, bar
• clustered areas
• easy to compare different sizes

12
Symbol scale

• establish relation between data and the areas or
  volumes of point symbols (Dent 1999, Slocum 1999)
• e.g. 2 mm2 represents 100 persons
• How many mm2 for 200 persons?
• How many mm2 for 500 persons?

13
(No Transcript)
14
Symbol scale

• establish relation between data and the areas or
  volumes of point symbols (Dent 1999, Slocum 1999)
• three main methods
• range-graded
• mathematical scaling
• perceptual scaling

15

• G

16
(No Transcript)
17
(No Transcript)
18
(No Transcript)