The Cartography & Visualization section encapsulates competencies related to the design and use of maps and mapping technology. This section covers core topics of reference and thematic maps design, as well as the emerging topics of interaction design, web map design, and mobile map design. This section also covers historical and contemporary influences on cartography and evolving data and critical considerations for map design and use.

GENERAL RESOURCES

Cartography and Visualization | GIS&T Body of Knowledge (ucgis.org)

Thematic map - Wikipedia

Data Presentation: Choropleth and Isopleth Mapping Techniques (geographyfieldwork.com)

Web mapping - Wikipedia

UNDERSTANDING OF GRAPHIC REPRESENTATION TECHNIQUES AND IMPLICATIONS

KEY CONCEPTS AND TERMINOLOGY

  • Thematic map is a type of map especially designed to show a particular theme connected with a specific geographic area.
  • Choropleth - areas are shaded according to prearranged key, each shading or color type represents a range of values.
  • Proportional Symbol - symbol drawn proportional in size to the size of the variable being represented.
  • Isarithmic or Isopleth - lines of equal value are drawn (contour lines) or ranges of similar values are filled with similar colors or patterns.
  • Dot - shows distribution of phenomena where values and locations are known - place a dot where the location of the variable is.
  • Dasymetric - alternative to choropleth - ancillary information is used to model internal distribution of the phenomenon.
  • Multivariate displays - putting more than two sets of data on one map (i.e. single map shows population density and annual rainfall and cancer rates)
  • Web mapping - process of using maps delivered by GIS - web maps are both served and consumed.

SAMPLE QUESTION

Which of the following statements about graphic representation techniques in GIS is true?

A) Graphic representation techniques are primarily used for aesthetic purposes in map design.

B) Graphic representation techniques have no impact on the accuracy of spatial analysis.

C) Graphic representation techniques can significantly influence how geographic data is perceived and interpreted.

D) Graphic representation techniques are only relevant for 3D visualization.

Answer: C) Graphic representation techniques can significantly influence how geographic data is perceived and interpreted.

Explanation: Graphic representation techniques play a crucial role in conveying spatial information effectively. The choice of symbols, colors, scales, and visual elements impacts how users understand and analyze geographic data. It’s essential to consider these implications when creating maps and visualizations in GIS12.

ADDITIONAL RESOURCES

Thematic map - Wikipedia

KEY CONCEPTS AND TERMINOLOGY

  • Map layout elements - a title, map, legend, map scale, supporting media, north arrow, metadata (sources, currency of information, projection, copyright, authorship)
  • Symbols - represent things on a map.
  • Map accuracy - difficult to assess, all maps show a selective view of reality - instead should ask if the map is appropriate for my purposes.
  • Map scale 1:100 - one inch represents 100 inches in the real world.
    • Large scale (more zoomed in) shows more detail than small scale (more zoomed out)
  • Symbolization variables - size, shape, orientation, pattern, hue, value
  • Quantitative:
    • Size – the size of the point or the thickness of a line
    • Value – the shade of the color such as dark red or light red
  • Qualitative:
    • Shape – for points different symbol
    • Pattern – lines having different styles such as dashed lines.
    • Hue – different colors, such as red and blue
  • Typography - the design of text, point size, line length, typefaces
  • Map Scales
    • Verbal scale - expresses in words a relationship between a map distance and ground distance: one inch represents 16 miles.
    • Visual scale - graphic scale or bar scale
    • Representative scale - representative fraction or ratio scale 1:24,000 - 1” = 24,000”
    • Absolute scale - system of measurement that begins at a minimum or zero point and progresses in only one direction.
    • Relative scale (arbitrary) - begins at some point selected by a person and can progress in both directions.
    • Display vs Data - The data is built at a certain scale/accuracy but once the data is displayed in any other format that the one it was made for, the scale gets warped. Ex: a map made as 9”x10” that is then scaled down and printed in a newspaper.
    • Large scale – small ratio between map units and ground units. Depict small areas such as USGS topographic maps or neighborhoods.
    • Small scale scale – large ratio between map units and ground units. Depict large areas such as countries or continents.

SAMPLE QUESTION

Which of the following design principles is most crucial for creating effective maps in cartography?

A) Visual Contrast: The use of colors and symbols to enhance map readability.

B) Figure-Ground: The arrangement of map elements in a balanced manner.

C) Hierarchical Organization: The inclusion of metadata for map features.

D) Balance: The choice of appropriate map projections.

Answer: A) Visual Contrast: Visual contrast plays a significant role in making map features stand out and ensuring legibility. It relates to how map elements contrast with each other and their background, influencing how users perceive geographic data12.

UNDERSTANDING OF SURFACE INTERPRETATION AND REPRESENTATION

Map interpretation (also known as map-reading) involves interpreting or understanding the geographic information portrayed on a map. It allows the reader to develop a mental map of the real-world information by processing the symbolized details shown on the map. Surface interpretation involves the process of understanding scale, direction, relationships, navigation and how landforms are represented and depicted in maps, both in 2D and 3D.

KEY CONCEPTS AND TERMINOLOGY

  • Aerial Map Interpretation:
    • Aerial photographs provide detailed views of the Earth’s surface from above.
    • Steps:
      • Patterns and Features: Look for recognizable patterns, shapes, and features (e.g., roads, buildings, rivers).
      • Scale Bar: Use the scale bar to determine the size of objects on the photograph.
      • Comparison: Compare the aerial photograph to a traditional map to identify landmarks and features.
      • Depth Perception: Recognize elevation changes based on shadows and perspective.
  • Topographic Map Interpretation:
    • Topographic maps represent the Earth’s surface using contour lines and other symbols.
    • Key Concepts:
      • Contour Lines: These imaginary lines connect points of equal elevation. Walking along a contour line keeps you on a horizontal plane.
      • Scale: The ratio of map distance to ground distance (expressed as a fraction).
      • Map Orientation: North arrow indicates geographic orientation. Magnetic declination accounts for the difference between magnetic and true north.
      • Contour Intervals: The vertical difference between adjacent contour lines.
      • Quantitative Data: Extract information like slope, distance, elevation, and relief.
      • Planimetric vs. Topographic Maps:
        • Planimetric maps show distances and directions but lack elevation information.
        • Topographic maps include contour lines for detailed land surface representation.
  • Process for Reading Topographic Maps:
    • Identify Features:
      • Locate rivers, lakes, roads, and other landmarks.
      • Understand the map’s scale and orientation.
    • Contour Lines:
      • Interpret contour lines to visualize landforms (ridges, valleys, hills).
      • Closer contour lines indicate steeper slopes.
    • Elevation and Slope:
      • Determine elevation at specific points.
      • Calculate slope by analyzing contour spacing.
    • Profiles and Cross-Sections:
      • Construct topographic profiles to visualize elevation changes along a line.
      • Understand landform characteristics.
  • Applications:
    • Geology: Mapping landforms, erosion, and geological features.
    • Engineering: Assessing terrain for construction projects.
    • Forestry, Ecology, and Recreation: Understanding landscapes.
  • Be able to read aerial and topographic maps and interpret features.
  • Be able to decide how a geographic feature should be represented in GIS.

SAMPLE QUESTION

Which of the following statements about surface interpolation in GIS is true?

A) Surface data represents distance values over an area, and it can be stored as cell values or deduced from a triangulated network of 3D faces.

B) Surface models allow you to store surface information in a GIS, approximating a surface by taking samples of values at different points and interpolating between them.

C) Contours are sets of lines of equal value across a surface, frequently created to represent discrete features on a map.

D) Surface interpretation refers to the process of converting 2D data into areas in GIS.

Answer: B) Surface models allow you to store surface information in a GIS, approximating a surface by taking samples of values at different points and interpolating between them. This representation is commonly used for visualizing terrain, elevation, and other continuous phenomena12.

UNDERSTANDING OF 2D AND 3D VISUALIZATION

KEY CONCEPTS AND TERMINOLOGY

  • 2D Mapping and Visualization:
    • Definition: 2D mapping deals with objects or images that have only two dimensions: length and width.
    • Representation:
      • Flat: 2D projections appear flat on a screen or surface.
      • Common Use: Traditional mapping applications, such as road maps and building blueprints, rely on 2D representations.
    • Examples:
      • Mapping Elements: Road networks, buildings, and geographical boundaries represented by lines, points, or simple shapes.
    • Applications:
      • Graphic Design: Used in graphic design, animation, and video games.
  • 3D Mapping and Visualization:
    • Definition: 3D mapping involves objects or images with an additional dimension of depth, providing an appearance of volume and realistic representation.
    • Representation:
      • Depth: 3D objects extend beyond flat surfaces, incorporating depth along with length and height.
      • Realism: Viewed from any angle or perspective, enhancing realism and interactivity.
    • Examples:
      • 3D Shapes: Cubes, cylinders, and spheres.
      • Mapping Elements: Spatial information, topography, and landscapes represented more accurately.
    • Applications:
      • Virtual Reality: Immersive experiences.
      • Architectural Design: Detailed 3D modeling.
      • Movies and Video Games: Realistic visualizations.
  • Contour Line:
    • A contour line is drawn on a topographic map to indicate ground elevation or depression.
    • These lines connect points of the same elevation.
    • They represent features such as mountains, valleys, rivers, and slopes.
  • Contour Interval:
    • The contour interval refers to the vertical distance or difference in elevation between adjacent contour lines.
    • It quantifies the change in elevation from one contour line to the next.
    • Index contours (usually every fifth contour line) are bolder and serve as reference points.
    • If the numbers associated with specific contour lines increase, the terrain elevation also increases. Conversely, decreasing numbers indicate a decrease in elevation.
  • Interpreting Contour Lines:
    • Spacing: Closer contour lines indicate steeper slopes, while widely spaced lines suggest gentler terrain.
    • Stream Crossings: Contour lines turn upstream as they approach streams, forming a “V” shape.
    • Ridges and Depressions: Sharp contour points indicate ridges, while rounded contours represent flatter areas.
    • Profile Drawing: Contour maps allow drawing terrain profiles to visualize elevation changes.3D mapping brings in z-value (e.g., elevation data)
  • An isoline is a line connecting points of equal value on a map, chart, or graph.
    • The prefix “iso-” comes from the Greek word meaning “equal.”
    • Isolines are commonly used to represent various features, including elevation, temperature, and other variables.
    • Isobars: Points of equal atmospheric pressure.
    • Isobaths: Depths of water with equal depth under water.
    • Isochrones: Points of equal time-distance from a specific location.
  • 3d mapping has also included building modeling.

SAMPLE QUESTION

Which of the following statements accurately describes the difference between 2D and 3D visualization in GIS?

A) 2D visualization represents features within the boundary of polygons or grid cells, while 3D visualization uses volumes to represent features.

B) 2D visualization is primarily used for aesthetic purposes, while 3D visualization focuses on spatial accuracy.

C) 2D visualization is limited to flat surfaces, while 3D visualization can project onto three-dimensional objects.

D) 2D visualization relies on raster data, while 3D visualization uses vector data.

Answer: A) 2D visualization represents features within the boundary of polygons or grid cells, while 3D visualization uses volumes to represent features. In 2D, features are typically shown as flat representations, whereas 3D visualization allows for a more immersive and spatially accurate experience12.