Test 1 (ch 1-4)

Map Purpose

- Locating points of interest - navigating - compiling complex data - convincing the reader of fact or hypothesis - comparing data - analyzing data

Questions to ask yourself in the design process

- what is the purpose? - who is the audience? - what is the medium? - under what conditions will it be viewed?

Projections

A mathematical conversion of points on the earths surface to a flat plane. Cylindrical, conic, azimuthal

Coordinate space

An agreed upon range of coordinates used to portray the features

Unprojected CS

Based on spherical coordinates, measured in degrees of latitude and longitude.

Projected CS

Converts spherical coordinated to planar coordinates using math equations. Projects 3D coordinates to a 2D map.

Continuous data

Data existing and measurable everywhere, such as temperature or elevation. Consist of rasters

Longitude

Distance east or west of the prime meridian, measured in degrees

Tangent conic

Has one standard parallel

Secant conic

Has two standard parallels

Latitude of origin/reference latitude

Latitude at which the y coordinates equal 0

Nominal data

Names or uniquely identifies objects. Usually portrayed on a single symbol map.

Types of data

Nominal, Categorical, Ordinal, interval, or ratio

Discrete data

Objects exist in a defined and specific location/space, such as houses and roads. Consist of points, lines, and polygons

Standard parallel

Occurs where the projection surface touches the ellipsoid, in the center of tangent projections

Medium

Paper map Electronic files Computer screen Projection screen

Azimuthal projection

Place a plane tangent or secant to the sphere

Oblique cylindrical

Places the line at an angle

Interval data

Places values along a regular numeric scale with no meaningful zero point, ex: elevation. values can be negative.

Ratio data

Places values along a regular scale with a meaningful zero point, ex: population. Cannot be negative.

Transverse cylindrical

Rotating the cylinder sideways that touches the prime meridian

Categorical data

Separates features into distinct categories, ex: rock type. Category names may be text or numeric. Portrayed with a unique values map.

Coordinate system (CS)

The choice of values

Central meridian

The line of longitude in the center of the map, where the x coordinates equal 0.

Source scale

The original scale or resolution the data are captured. Impacts detail and accuracy of the data set.

Extent

The range of x-y values present in the data

Map scale

The ratio of distance on the map to distance on the ground. 1 cm on map = 100,000 cm on ground.

Ordinal data

Type of categorical data, that ranks categories along an arbitrary scale, ex: snail habitats. Based on some quantitative measure.

Types of coordinate systems

Unprojected and projected

Generalization

Used to simplify map feature for clear display. The smaller the map is, the less detailed it will be.

cylindrical projection

Uses a cylindrical surface that touches the earth at the equator

Artistic principles

Visual hierarchy - visual center - rule of thirds - alignment - negative space - size of elements

Map Audience

Who will be viewing the map? What is their expected level of knowledge? Ab the subject and maps Do they have special requirements? Color blindness, large print

Conic projection

based on setting a cone on the sphere

Raster model

designed to store continuous data by breaking a geographic area into small cells or pixels. A single numeric value stored in each.

Vector model

designed to store discrete data using three basic shapes, known as features; points, lines, and polygons

Latitude

distance north or south of the Equator, measured in degrees

Scale range

specifies the range of scales for which the display of the data is valid so that it will only be shown at those scales