Cartography – Maps & Scale YouTube Lecture Handout

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Agenda

• Data and its types
• Map and Scale
• Analyzing Maps

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Types of Data

Idiographic vs. Nomothetic

Map

• Map is graphical representation of real world.
• Art of map making = Cartography
• Maps can be:
  • Reference or Base Maps: Show natural and human-made objects from geographical environment with an emphasis on location, atlas or topographic maps
  • Thematic Maps: Geographical distribution of one phenomenon or spatial associations that occur between a number of phenomena
    • Isopleth maps - Isolines connect points of equal magnitude.
    • Choropleth map - tonal shadings are graduated to represent areal variations in number or density within a region, usually a formal region.

Topographic Map

Thematic Maps

• Quantitative:
  • Choropleth: Color gradient
  • Chorochromatic: Various Color
  • Choroschematic: Symbols
  • Isopleth: Lines
  • Proportional Symbols: Size of symbols
  • Dot Density Maps: Population
• Qualitative

Why We Need Maps?

• To represent a larger area than we can see
• To show a phenomenon or process that is not visible by eyes
• To present information concisely
• To show spatial relationships

How to Prepare Maps?

• By actual survey
• By photographs
• By free sketches
• By Computer Maps

Elements of Scale Map

• Symbols and a legend
• Scale
• Direction (indicated by the north arrow)
• Map grid or coordinate system
• About the map (date created, title, author, source information)

Characteristics of Map

Reading Map is Indeed an Art!

• Maps are selective views of reality
• Size of the map relative to reality (scale)
• What՚s on the map (symbolization)
• Shape of the map (projection)

Scale

• Scale is about distance.
• How long?
• How far?
• How wide?
• How far on the map and how far on the ground?

Map Scale

• Representative Fraction: Is a ratio like 1: 1000
• Verbal Statement: 1: 1,000, 000 verbally is “1 centimeter on the map equals 10 kilometers on the Earth՚s surface”
• Graphic Scale

1: 25,000 Scale

• 1 centimetre (cm) on map = 25,000 cm on the ground
• 1 cm on the map = 250 metres (m) on the ground
• 4 cm on the map = 1 kilometre (km) on the ground

Analyzing Map Scale

Types of Scale: Comparative Scale

Diagonal Scale

Vernier Scale

Time Scale

Reduction & Enlaargement

• After reducing a map from 1: 10,000 to 1: 50,000 scale, the new map is, the original line or scale & times the area.
• After enlarging a map from 1: 100,000 to 1: 20,000 scale, the new map is times the original line or scale & times the area of the original scale.
• If a map with scale 1: 100,000 is enlarged by 10 times the new scale can be calculated as follows. Assume that the new scale is , then, or , so & enlarged scale is .

Reduction/Enlargement by RF

• When the map is enlarged the RF is decreased. E. g. , if the original map with scale 10 cm = 5 km, is enlarged 4 times, the new RF will be 1: 12500

Maps Based on Scale

• Cadastral or Revenue Maps: Large scale 16 - 20 inches to 1 mile
• Topographical Maps: Single purpose, 1 in = 1 mile
• Wall Maps: Depict Large Area 1 in = 4 miles
• Atlas Maps: Small-scale chorographical, 1: 2000000

Map Symbols

• Symbols are a code instead of text
• Symbols can be
  • Point: Each symbol count as one occurrence
    • Qualitative: Explains location
    • Quantitative: Shows distribution
  • Line: One-dimensional for borders, roads etc.
  • Area: two-dimensional like garden, plot etc.
• Consider shape, size, orientation, pattern, color, value

✍ Manishika