ways of modelling spatial data and visual hierarchy

points vs lines vs areas (the three spatial dimensions)

points = things like cities and landmarks
lines = things like roads or artificial things (i.e. boundaries and things that arent actual features of the earth)
areas = represents bodies of water/land

things to consider when picking points, lines, and areas

• the importance of scale (ex: a river on a smaller scaled map could be represented as a line, but on on a larger scaled map it could be represented as an area)

• choice of dimension is dependent on the nature of the data, the scale of the data, and the application of data (what is the point of the map)

  • ex: if the map was made to show where to park: points can be used for area symbols of where to park, where the picnic area is, etc.)

• think about symbolizing a three dimensional world in a 0, 1, 2 dimensions

  • a point = 0 dimensions: a location

  • a line = 1 dimension: a location with length (ex: a river line)

  • area = 2 dimensions: a location with length and width (ex: the ocean)

discrete vs continuous data

Discrete data = describes phenomena that occurs at a distinct location with space between

• Isolated points, nothing happening between the points

• Ex: school locations; there are schools throughout, but there is no schools between the school locations that is connecting the schools together

Continuous data = phenomena occurs throughout a region at any and every location

• Ex: elevation data; it is occurring at every point of the data (even if you don't know what that elevation is)

There will be moments where there is a continuous phenomena but you only have discrete data

• you can interpolate and estimate what the data might be with a continuous phenomena

• but you cannot interpolate discrete data

abrupt vs smooth data

Abrupt = values change suddenly between adjacent points or areas

• Ex: a cliff's elevation; moves abruptly

Smooth data = values change gradually

• Ex: % of land covered by farm land by state; on the west coast there will be a medium amount and as you move to the mid west there is a greater amount and then it dwindles down as you move east

is the data for temperature, high and low, and perception continuous or discrete? smooth or abrupt? how would you symbolize them?

• Temperature is continuous, changing smoothly, represented by area

• High and low looks discrete, but it is continuous we just don't know all the data, changes abruptly, represented by points

• Precipitation is continuous, changes smoothly, and is represented by area symbols

what are the four levels of measurement in maps

1. nominal (naming) = describes data that is qualitative or categorical → data tells you how you can group things together, but there is no order of value

• ex: a map of religions

2. ordinal = grouping things together but there is a hierarchy involved (this hierarchy doesn’t involve numbers, it is purely qualitative)

• ex: a map of regions based on whether it is hot, warm or cool

3. interval = used for numerical data; groups things together and order them with an equal numeric difference between the two groups → has an arbitrary zero point (cannot use mathematical equations)

• ex: a temperature map with intervals of temperature: 21-30 degrees (dark red), 11-20 degrees (red), 0-10 degrees (pink)

4. ratio = groups things together and order with numeric differences with a non arbitrary zero point (can use mathematical equation) → most numerical/quantitative data will be measured in ratio data

• ex: 101-150 kelvin (dark red), 51-100 kelvin (red), 0-50 kelvin (pink) → can even say 100 is twice as large as 50

visual variables

= how we change our symbols to vary them and make them represent different sets of data

ways we can change variables:

• chroma (saturation) and tone (value) is used to create gradients → good for ordinal, interval, ratio data, and qualitative data

• hue is used to separate colours → good for qualitative and nominal data

how to vary qualitative data and quantitative data

qualitative data = vary shapes, patterns of lines or areas, and hue

quantitative data = vary chroma/tone/shade and vary points and thickness of lines

different ways point, line, and area symbols can be varied

mimetic symbols

= common symbols found on Atlas of Canada Topographic maps

• when using these symbols use associative symbols

four cartographic conventions

= rules/guidelines for cartography; things that cartographers usually do, and what map readers are expecting things to mean → a guideline for better readability

• colour connotations (ex: blue used for water features)

• point symbols (ex: star circle for capital city)

• line symbols (ex: solid lines for permanent features like rivers)

• area symbols (ex: green area for parks) → mostly color connotation

visual hierarchy

= using similar and contrasting symbols in combination → how things go together to make it pleasing to the eye and easy to understand

• important things on a map should be darker/bolded

• similar things need to be similar in colour/symbols and contrasting things need to be different (ex: bodies of water should be blue, land should be green)

• consider the purpose of the map

• consider the technical and perceptional limitations

  • perceptual limitations = human eye can only differentiate 5 different color gradients

  • technical = low resolution files may not pick up detailed symbols

• color connotations of different cultures