P 289 | GIS FOR CDRA

Geographic representation is often done in two ways:

• Discrete fields

• Discrete objects

• Continuous fields

• Continuous Objects

is concerned with the Earth’s surface or near-surface, “what to represent” and “how to represent it”

• Discrete fields

• Discrete objects

• Continuous fields

• Continuous Objects

• Geographic representation

divides the world into arrays of cells and assigns attributes to the cells

all lines are captured as points connected by straight lines (polylines), and an area is captured as a series of points or vertices connected by straight lines (polygon) with same starting and end point

Because maps are flat, some of the simplest projections are made onto geometric shapes that can be flattened without stretching their surfaces. These are called________.

Developable surfaces often used in map projection are:

• cones

• cubes

• cylinders

• dodecahedron

• planes

A _____systematically projects locations from the surface of a spheroid to representative positions on a flat surface using mathematical algorithms.

The _______ is one of the most common cylindrical projections, and the equator is usually its line of tangency. Meridians are geometrically projected onto the cylindrical surface, and parallels are mathematically projected. This produces graticular angles of 90 degrees.

project map data onto a flat surface touching the globe. A planar projection is also known as an azimuthal projection or a zenithal projection.

The major components of the graticule are the:

• Lines of the Latitude and Longitude

• international date line

• prime meridian

• equator

• the north and south poles