mapping networks
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Mapping Networks. Or, the costs and benefits of abstraction. Mapping Networks. What are Networks Elements of Network Mapping Schematic Maps. Networks, Defined. What is a network?. Networks, Defined. What is a network? An interconnected group or system - PowerPoint PPT PresentationTRANSCRIPT
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Mapping Networks
Or, the costs and benefits of abstraction
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Mapping Networks
What are Networks
Elements of Network Mapping
Schematic Maps
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Networks, Defined
What is a network?
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Networks, Defined
What is a network?An interconnected group or systema system of intersecting lines or channels;
"a railroad network"; "a network of canals”
Networks are important in geography and mapping
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Elements of Networks
Networks are a collection of:Nodes
AKA: Vertices
Edges AKA: Links
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Early Quantitative Geography
The Seven Bridges of KönigsbergFamous network problem based on an
actual place (An urban riddle)Let’s try and solve the riddle…
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The city of Königsberg is set on the Pregel River.
The city included 2 large islands and was connected to the mainland by exactly 7 large bridges
Is it possible to walk a route that crosses each bridge exactly once?
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Is it possible to walk a route that crosses each bridge exactly once?
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Is it possible to walk a route that crosses each bridge exactly once?
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Is it possible to walk a route that crosses each bridge exactly once?
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The problem becomes simpler with abstraction….
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So, what’s the solution?
There is no solution! It is impossible.In 1736, Leonhard Euler proved it
impossibleFormulated solution in terms of “graph
theory” Eliminated all features except land masses
and the bridges (nodes, edges)
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A Eulerian Path
A solution did not exist Problem concerned degrees of nodes
Degree of a node is the number of edges touching it
Konisberg: 1 5-degree node, 3 3-degree nodes
Euler proved that a “circuit” is only possible if there are exactly 0 or 2 nodes of an odd degree This type of walk is called a Eulerian Path
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Harry Beck
Electrical Draftsman, English, 1903-1974
Created the most famous network map of all-time
What is it?
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Beck’s Original
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Direct descendents
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The “Tube Map”
Network Map of the London Underground
A Schematic Diagram
More Topological than Geographic
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Tube Map
Emphasizes connectivity over geographic congruence
How?
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Octilinearity
Every line on the map is drawn in one of 8 directionsMultiples of 45 degreesOctilinearityReduces geographic congruence,
increases clarity
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The Beck Map
First drafts made between 1931-1933
Designed in the form of the electrical circuitry diagrams of that time
Style adopted worldwide
Subway maps are among the most used network maps…
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Dangers of the schematic style
What are the dangers of the beck map?
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Dangers of the schematic style
What are the dangers of the beck map?
Result in warped mental maps of actual geographySince distance and direction are inaccurate
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Roman place-to-place maps
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Peutinger’s Table
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Speaking of routes……
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1643 Matthew Simons in A Direction for the English Traviller pub. Thomas Jenner (distance tables by John Norden)
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Santa Fe Trail
Zebulon PikeMap of the "Santa Fe Trail"St. Louis: ca. 1806Manuscript mapNational Archives, Washington, D.C.
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First map of the Arpanet
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Map of the Internet
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Conclusion
“Graphs” are useful to simplify geographic spaces
Sacrifices are made to achieve increased clarity