GIS - Geographic Information System Cartography and Visualization Questions and Answers — Questions and Answers
Question 1: A cartographer is creating a map to show population density for every county in the United States. The data is continuous but has been aggregated into political boundaries. Which type of thematic map would be most appropriate for visualizing this data?
- Isarithmic map
- Choropleth map (Correct answer)
- Dot density map
- Cartogram
Correct answer: Choropleth map
A choropleth map is ideal for displaying data that has been aggregated into enumeration units, such as counties or states. [1, 13, 14] It uses color or shading to represent the intensity of a variable, like population density, within those predefined areas. Isarithmic maps are for continuous data without predefined boundaries, dot density maps show distribution, and cartograms distort area to represent a variable. [1, 9, 24]
Question 2: When designing a map, the principle of guiding the viewer's eye to the most important elements first is known as:
- Generalization
- Figure-ground relationship
- Visual hierarchy (Correct answer)
- Data classification
Correct answer: Visual hierarchy
Visual hierarchy is the cartographic principle of arranging map elements to clearly show their order of importance. [3, 19] Important elements (like the main map theme) are made more prominent through size, color, and placement, while less important elements (like scale bars or source notes) are more subdued. [12, 18]
Question 3: A GIS analyst is classifying a dataset of annual household incomes for a city's neighborhoods. The data is heavily skewed, with many low-income households and a few very high-income households. To create a balanced map that highlights relative social stratification, which classification method would be most effective?
- Equal Interval
- Quantile
- Standard Deviation
- Natural Breaks (Jenks) (Correct answer)
Correct answer: Natural Breaks (Jenks)
The Natural Breaks (Jenks) method is designed to identify natural groupings inherent in the data. [2, 5] It minimizes variance within classes and maximizes variance between classes, making it well-suited for unevenly distributed or skewed data, as it can isolate clusters and outliers effectively. [15]
Question 4: Which of the following map projections is best suited for a navigational chart of the world's oceans, as it preserves direction (rhumb lines are straight lines), but significantly distorts area near the poles?
- Albers Equal Area Conic
- Lambert Conformal Conic
- Mercator (Correct answer)
- Robinson
Correct answer: Mercator
The Mercator projection is a conformal projection famous for its use in navigation. It preserves angles and shapes locally, and lines of constant bearing (rhumb lines) are straight, which is invaluable for sea travel. Its major drawback is the extreme distortion of area as latitude increases, making landmasses like Greenland appear enormous.
Question 5: A map displays qualitative, categorical data, such as land cover types (e.g., forest, urban, water, agriculture), using different colors or patterns for each category. This type of map is best described as a:
- Choropleth map
- Chorochromatic map (Correct answer)
- Bivariate map
- Isopleth map
Correct answer: Chorochromatic map
A chorochromatic map (also known as a qualitative area map) is used to display nominal or categorical data. [6] Each distinct area on the map is colored or patterned according to the category it belongs to, such as soil type, vegetation, or political affiliation. Unlike a choropleth map, it does not represent quantitative data. [6]
Question 6: In a scenario where a cartographer needs to map the precise locations of individual events, such as traffic accidents or disease cases, while also showing their spatial distribution, which thematic map type would be most appropriate?
- Graduated Symbol Map
- Cartogram
- Proportional Symbol Map
- Dot Density Map (Correct answer)
Correct answer: Dot Density Map
A dot density map uses dots to represent a specific count of a feature within an enumeration area (like a census tract). [9, 14] It is effective at showing the distribution and density of discrete phenomena across a landscape, making it ideal for visualizing individual events like accidents or disease cases. [24]
