overview - learnlinelearnline.cdu.edu.au/.../w2_makingmaps_2015_handouts.pdf• maps are created to...
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Week 2: Making maps, data visualisation, and GIS output
ENV208/ENV508 – Applied GIS
Overview
• GIS Output
• Map Making
– Types of Maps
– Key Elements
GIS Output Formats
• Table
• Graph
• Statistics
• Maps
Map Making
• Maps are created to communicate the information present in spatial data to a map-reader
• Goal is to communicate the spatial information portrayed on the map as effectively and efficiently as possible
• Ideally, reading a map is both a pleasing and enlightening experience for the map-reader
• Most popular use of GIS is for making maps
GIS Data Output Methods
1. Monitor display
2. Exporting to a digital file
3. Printing or plotting on paper
GIS Data Output Methods
1. Monitor display
– Take computer and data to client
– Most easily updated
– On the spot modifications
– Cheapest
– Ephemeral
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GIS Data Output Methods
2. Exporting to a file – Data in digital format
– Transferred to other computer or software system
– Disc, USB… easily transportable
3. Printing or plotting on paper – Most common
– Generates hardcopy
– Knowledge of cartography desirable
Important Considerations
• Need to be clear about intended audience – Who is the product for?
• Specialist or general public? • Adult or child? • Type and form of presentation? • Scale and accuracy needed?
• Budget constraints
• Technological constraints – Appropriate file format – Delivery mode
Success of GIS is often gauged by quality of the output !
The Cartographic Process
• Cartography
– The science or art of making maps
– Purpose to transmit information, knowledge or location and/or facilitate travel
– Greek.. Chartis (map) and graphein (to write or draw)
– Oldest maps date back to 7-6th century BC
– Thrower, N. J. W. (1999) Maps & Civilization: Cartography in Culture and Society, Chicago: University of Chicago Press, 326 p.
The Cartographic Process
• Cartography – The science or art of making maps
The Cartographic Process
1. Think about what the distribution of the phenomenon might look like
2. Decide on the purpose of the map and the intended audience
3. Collect data that are appropriate for the purpose of the map
4. Design and construct the map using appropriate cartographic principles
5. Determine if the map reader understands the map content
Types of Maps
• Two general map types:
– Reference or formal maps (location, navigation)
– Thematic or transitory (visual display, information analysis)
•Maps contain distortions from:
– Scale
– Projection
– Symbology
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Types of Maps
Reference or formal maps
• Depict selected details of the environment as accurately as possible – Road maps, political maps, physical maps, topographic maps
– Location, distance, orientation, reference, known features
Types of Maps
Reference or formal maps
• Depict selected details of the environment as accurately as possible – Road maps, political maps, physical maps, topographic maps
– Location, distance, orientation, reference, known features
8/ 03/ 2015 7:16 pmCharles Darwin University to Darwin NT - Google Maps
Page 1 of 1https:/ / www.google.com.au/ maps/ dir/ Charles+ Darwin+ University,+ E…a0fc9f59043f:0x30217a82a247c20!2m2!1d130.8417772!2d- 12.4628271
Charles Darwin University, Ellengowan Dr Darwin NT
Drive 13.0 km, 16 min
Charles Darwin University, Ellengowan Dr
University E Dr Dripstone Rd
north-west University E Dr
right University E Dr
3rd University E Dr
Bagot Rd National Highway 1 Knuckey St
2nd Dripstone Rd
2nd Lakeside Dr
right Trower Rd
Bagot Rd
right Bagot Rd
National Highway 1
left McMinn St
right Knuckey St
Darwin NT
Map data ©2015 Google
Types of Maps Thematic maps
• Depict the general spatial pattern of selected data or features (e.g. population distribution) – Qualitative (categorical data e.g. soil type) – Quantitative (numerical data e.g. pH values of soil)
• Usually have a base map with a thematic graphical overlay
• Producer includes only the amount of information necessary to convey the map message
• Emphasise a particular feature or set of data – Choropleth maps – Dot-density maps – Proportional symbol maps – Flow maps – Isoline maps – Cartograms
Thematic maps
•Choropleth maps: use colour shading to represent different quantities or values
- From Greek choros (place) and pleth (value) - Use when data occur within well-defined units or are numeric interval data - Involves some method of data classification - Generally derived from values describing attributes of non-overlapping
polygons
Thematic maps
•Choropleth maps: use colour shading to represent different quantities or values
- From Greek choros (place) and pleth (value) - Use when data occur within well-defined units or are numeric interval data - Involves some method of data classification - Generally derived from values describing attributes of non-overlapping
polygons
Thematic maps
•Choropleth maps: use colour shading to represent different quantities or values
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www.bom.gov.au
Thematic maps
•Dot-density maps: use points on a map to correspond with occurrence
www.bom.gov.au
• Isoline maps: use lines to connect points of equal value (isotherms for temperature, isohyets for rainfall, contours for elevation)
Thematic maps Average annual rainfall
Thematic maps • Isoline maps: use lines to connect points of equal value
(isotherms for temperature, isohyets for rainfall, contours for elevation)
Temperature and sea level pressure •Graduated symbol maps: draw attention to big
concentrations of your distribution by varying symbol size to concentration in an area
Thematic maps
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Thematic maps • Flow maps: show the origin of some flow/movement between
places, with line width proportional to quantity of movement.
Thematic maps •Cartograms: spatial features are drawn (distorted) in
proportion to the value of an attribute
Thematic maps •Cartograms: spatial features are drawn (distorted) in
proportion to the value of an attribute
Thematic maps • Typographic maps: use typography as line and area map
symbols
Activity
Find an example of each of the following maps: • Reference • Choropleth • Dot-density • Isoline • Graduated symbol
– What data/information layers were necessary to create the map?
– How is it effective in communicating its message
– What audience is the map intended for?
– What do you really like about the map?
– Would you make any adjustments to improve the map?
Keep the maps saved/open for later
http://thelandofmaps.tumblr.com/
Landofmaps.com
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Key map elements
Two basic components:
1. The map itself
2. Information about the map (‘marginalia’)
It is completely up to the map maker to decide where
this information is shown on their map
1. The map itself
2. Marginalia
• Title
• Orientation
• Date
• Map Legend/symbols
• Datum/projection
• Scale
• Location
• Grids and Graticules
• Product Information
Marginalia
Title: What is the purpose of the map?
• What is being mapped, where, when?
Marginalia
Orientation: Which direction is north?
• North arrow
• Compass rose
• North is usually pointing towards
the top of a map
N
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Marginalia
Date: When the map made (or updated)
Marginalia
Map symbols and Legend: What do the
classes and symbols on the map represent?
• Keep the design of any symbols as
simple and as different from each other
as possible
• Give sufficient information to ensure
your map is not misread
A single tree? A forest? A national park?
Marginalia
Map symbols and Legend: Describe what is on
the map
• Shape – a rectangle for a building, a tree
for a forest
• Size – the larger a feature the higher the
importance of the feature
• Colour – blue for water, green for
vegetation
Map symbolism
Map symbolism has become pretty standardised, so that even foreign maps are not all that hard to read
Map symbols should be readily recognizable and suited to the scale of the map
Three main categories:
• pictorial symbols
• colour symbols
• value symbols
Colour symbolism
• Blue – water features
• Green – vegetation
• Brown – topography or terrain
• Black – human artefacts such as individual buildings, railroads
• Red – larger human artefacts such as highways, roads, urban built-up areas
• Purple – human artefacts since previous map revision
Map symbolism Map symbolism
• Use existing ‘standard’ symbols/colours if possible
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Map symbolism
• Use existing ‘standard’ symbols/colours if possible
Map symbolism
• Use existing ‘standard’ symbols/colours if possible
Map symbolism
• Human limitations
- About 12 colours
- After that use patterns as well
- About 7-8 shades of the same colour
• Colour blindness
• Contrast
• Common sense
Map symbolism
Value symbols - Identify something
- Show it’s location
- Tell something about the amount of that
something in that location
Map types:
- Dot maps
- Graduated symbol maps
- Divided circle map
- Bar chart map
Marginalia
Datum/Projection: The system whereby the information of
the Earth is transferred to a two-dimensional area (a map)
• Often sought by map users, often many years after
the map was published
Map scale: How does distance on the map
relate to distances on the ground?
• Scale statement (e.g. “one cm equals one
kilometre”)
• A ratio or fraction (unitless value)
• A scale bar
Marginalia
• A map without a scale is basically just a diagram or picture
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• A small scale map generally shows less
detail but cover larger parts of the earth
• A large scale map is one in which a given
part of the Earth is represented by a
large area on the map (usually show
more detail)
Scale Marginalia
Location: The location of the map on the Earth
• Draw a recognisable region with an
indication of the mapped location
Marginalia
Grid and Graticules : How to find places on the map
• Alphanumeric grids: Columns are lettered and run down
the page, rows are numbered and run across the page
• Latitude and longitude: geographical coordinates in
degrees, minutes, and seconds
• Cartesian: More useful where the area of interest is a relatively small portion
of the Earth’s surface
Marginalia
Product information:
• Who produced/published the map? (including
organisations, sponsors etc.)
• Date of publication and/or information shown on
the map
• Known limitations of the information (e.g. accuracy)
• Methodology used to produce the map
• Edition (unless it is the first edition)
• Copyright
Generally, too much information is better than too little
Marginalia
Product information:
• Who produced/published the map? (including
organisations, sponsors etc.)
• Date of publication and/or information shown on
the map
• Known limitations of the information
• Methodology used to produce the map
• Edition (unless it is the first edition)
• Copyright
Generally, too much information is better than too little
Key map elements
Two basic components:
1. The map itself
2. Information about the map (‘marginalia’)
It is completely up to the map maker to decide where
this information is shown on their map
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Overall layout
• Create final product that is informative, accurate, and aesthetically pleasing
• Visual balance is very important • Map should be centre of display and
have the most visual impact • Exercise in graphic design
• Legibility
• Colour schemes • Use contrast to enhance the
infromation from the background (contextual information)
• Use colour appropriately
Go back to the maps you found earlier and consider the key map elements.
• Title
• Layout
• Orientation
• Date
• Legend/symbology (shape, size, colour)
• Datum/projection
• Colour
• Scale
• Location
• Grids and Graticules
• Product information
Do your maps have all/any of these features?
Would the addition of any of these features help an audience to understand their message?
Activity