GIS Cartography and Visualization 5 — Questions and Answers
Question 1: A map uses circles of varying size to show city populations. This is an example of a:
- Choropleth map
- Dot density map
- Proportional symbol map (Correct answer)
- Isarithmic map
Correct answer: Proportional symbol map
A proportional symbol map scales symbols (often circles) in area or volume proportionally to the data value they represent.
Question 2: Which map distortion property is preserved by a conformal projection?
- Area
- Distance
- Shape (local angles) (Correct answer)
- Direction from center
Correct answer: Shape (local angles)
Conformal projections preserve local angles and therefore the shape of small features, but distort area at regional scales.
Question 3: What is a 'diverging' color scheme best suited for on a thematic map?
- Showing categories with no inherent order
- Showing data that ranges from a meaningful midpoint (e.g., above/below average) (Correct answer)
- Showing gradients from zero to maximum
- Showing time-series change
Correct answer: Showing data that ranges from a meaningful midpoint (e.g., above/below average)
Diverging palettes use two contrasting hues that diverge from a neutral midpoint color, highlighting deviations above and below a critical value.
Question 4: What is map 'symbolization' in cartography?
- Assigning coordinate projections to a dataset
- The process of selecting and designing graphic symbols to represent geographic features (Correct answer)
- Converting raster data to vector format
- Georeferencing a scanned image
Correct answer: The process of selecting and designing graphic symbols to represent geographic features
Symbolization is the cartographic process of choosing visual variables (color, size, shape) to represent the characteristics of geographic features on a map.
Question 5: Which term describes the smoothing of jagged polygon or polyline boundaries in GIS to improve visual appearance?
- Clipping
- Smoothing or generalizing (Correct answer)
- Dissolving
- Buffering
Correct answer: Smoothing or generalizing
Smoothing (or simplification) algorithms reduce vertices and soften sharp angles in digitized features, improving cartographic appearance.
Question 6: On a standard US Geological Survey (USGS) 7.5-minute topographic quadrangle, what scale is used?
- 1:100,000
- 1:250,000
- 1:24,000 (Correct answer)
- 1:50,000
Correct answer: 1:24,000
USGS 7.5-minute quadrangles are published at a scale of 1:24,000, providing detailed topographic information for approximately 64 square miles.
Question 7: Which element of Bertin's visual variables is most effective for distinguishing nominal (categorical) map classes?
- Value
- Size
- Hue (Correct answer)
- Orientation
Correct answer: Hue
Hue (distinct colors) is the most effective visual variable for differentiating unordered, nominal categories because it implies no rank order.
GIS Cartography and Visualization 5
A map uses circles of varying size to show city populations.
This is an example of a: