15.1 Mapping Techniques and Projections

Maps are essential tools for visualizing geographic data. They transform the Earth's curved surface onto flat planes using various projections, each with its own strengths and limitations. Understanding these techniques is crucial for creating accurate and effective spatial representations.

Mapping involves more than just projections. It includes coordinate systems for precise location, essential map elements like scale and legend, and symbology to represent features. Topographic maps add depth by depicting terrain through contour lines and color schemes, enhancing our understanding of landscapes.

Map Projections and Coordinate Systems

Representing the Earth's Surface

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  Gall-Peters Projection: Compare Map Projections View original

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Top images from around the web for Representing the Earth's Surface

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  License Info: Mercator View original

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  Gall-Peters Projection: Compare Map Projections View original

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• Map projections transform the curved surface of the Earth onto a flat plane
• Mercator projection preserves shape but distorts size, especially near the poles (Greenland appears larger than Africa)
• Robinson projection balances shape and size distortions, providing a visually appealing compromise
• Gall-Peters projection preserves relative size of areas but distorts shape, particularly near the poles
• No single map projection can perfectly represent the Earth's surface without distortions

Locating Points on Earth

• Latitude measures the angular distance north or south of the equator, ranging from 0° to 90° (North Pole) or -90° (South Pole)
• Longitude measures the angular distance east or west of the prime meridian (0°), ranging from -180° to 180°
• Coordinate systems, such as the geographic coordinate system, use latitude and longitude to specify locations on Earth
• Decimal degrees (DD) express latitude and longitude as decimal fractions (e.g., 40.7128° N, 74.0060° W for New York City)
• Degrees, Minutes, Seconds (DMS) format represents latitude and longitude using units of degrees, minutes, and seconds (e.g., 40°42'46" N, 74°00'21" W for New York City)

Map Elements and Symbology

Essential Components of Maps

• Cartography is the art and science of making maps, focusing on design and communication
• Scale represents the relationship between a distance on the map and the corresponding distance on the ground
  • Large-scale maps show a small area with high detail (e.g., 1:10,000)
  • Small-scale maps show a large area with less detail (e.g., 1:1,000,000)
• Legend explains the symbols, colors, and patterns used on the map, providing a key for interpretation
• Symbology refers to the use of symbols, colors, and patterns to represent features and attributes on a map
  • Point symbols represent discrete features (e.g., cities, landmarks)
  • Line symbols represent linear features (e.g., roads, rivers)
  • Area symbols represent polygonal features (e.g., countries, lakes)

Topographic Maps and Terrain Representation

• Topographic maps depict the Earth's surface, including relief (elevations and depressions) and natural and human-made features
• Contour lines connect points of equal elevation, allowing users to visualize the shape and steepness of the terrain
  • Closely spaced contour lines indicate steep slopes
  • Widely spaced contour lines indicate gentle slopes
• Hypsometric tints use colors to represent elevation ranges (e.g., green for low elevations, brown for high elevations)
• Shaded relief simulates the appearance of sunlight and shadows on the terrain, providing a 3D-like effect