Lecture 3: Mapping 101 / PE_1

The Cartographic Process, Democratization of maps, Types of maps Classification, symbolization, Scale Ellipsoid/Datum/Proj/Coordinate, Thematic map types

Latitude (0-90)

Measures your position north/south of equator

Longitude (0-180)

Measures your position east/west of the prime meridian (greenwich)

Quantitative

How many/much?

Number / Stats

Measure and test

Statistical analysis

Qualitative

Why?

Observation, symbol, word

Observe and Interpret

Grouping of common data / non stats

How do maps reflect the worldview?

Maps visually encode politics, cultural bias, and spatial values

They quietly shape how people perceive local, regional, and global importance

How are maps instruments of communication?

influencing relationships among the environment, map maker, and map user

Space and Attribute are________ in GIS

DYNAMICALLY LINKED

Scale

map distance to ground distance

Verbal Scale

1 inch represents 15 miles

Representative Factor (RF) Scale

1:50,000

Graphic Scale

picture

Necessary parameters for digital mapping

• Ellipsoid

  • Mathematical model of Earth (shape)

• Datum

  • Ellipsoid above related to real-world features (anchor)

• Projection

  • Real-world features must be transferred from 3D to 2D

• Coordinate system

  • Grid systems of coordinates for locational reference

Planar Projection

• Only one hemisphere at a time

• Polar viewpoint

• Latitude lines form concentric circles

• Longitude lines radiate from center

• “Unclipped” map is circular

Conic Projections

• Poles normally are the viewpoint

• Only represent one hemisphere

• Good for mid-latitudes

• Used for places with East-West extent (US)

• “Clipped” map is a section of a circle

Cylindrical Projection

• Equator normally the viewpoint

• Typically used to represent entire world

• Latitude/longitude lines perpendicular

• “Clipped” map is rectangular

The Cartographic Process

What are the two types of maps?

Reference and Thematic

Reference Map

Show where geographic features and locations are in the real world

Thematic

display specific data, statistics, or abstract concepts distributed across a space

How are Spatial Data portrayed on maps?

Points, lines, polygons, raster pixels

What are the democratization of maps?

increasing access, use, and appreciation for all types of maps, as well as driving map innovations.

Nominal, Ordinal, Interval, Ratio

No order

Ordered

Differences between measurements, no true zero

Differences between measurements, true zero exists

Symbolization

Qualitative Data, Categorical Difference

Ellipsoid

Mathematical model of Earth (shape)

Datum

Ellipsoid above related to real-world features (anchor)

Projection

Real-world features must be transferred from 3D to 2D

Coordinate System

Grid systems of coordinates for locational reference

Thematic map types

• Choropleth (shaded regions)

• Proportional Symbol (scaled shapes)

• Dot Density (point counts)

• Isarithmic (contour lines)

• Cartogram (distorted area)

• Flow (movement lines)