GIS GEOG 2270 Douglas College - quiz 2

geographic coordinate systems are based on:

spherical 3D coordinate

Geographic Coordinate Systems are also called:

non projected coordinate systems

Geographic Coordinate systems use:

Angular units like Latitude and Longitude

Latitude

Angular distance north or south of the equator. (shaped like the rungs of a ladder)

Longitude

Angular distance east or west of the equator. north to south lines.

Graticule

lines of latitude and longitude on a globe

Projected coordinate systems are based on:

a planar set of coordinates created by projecting a 3d map on a 2d surface

All spacial data must have a

Geographic Coordinate system

Different map layers must be

based on the same coordinate system to work

the 3 models of the earth are

Sphere, ellipsoid, geoid

Spheres are

simple, good for large maps (small scale), only requires a radius

Ellipsoids are

accurate enough and good for maps of smaller areas

Geoid

gravity and sea level. lumpy. good for precise measurements of location

3d models of the earth include info about

shape of model, origin, and known points on the earth's surface. serves as a baseline for measurements

Datum shift

A change from one datum to another. which can result in substantial horizontal shifts of point positions

Vertical Datums

define elevations in relation to a surface (sea level, geoid)

lat and long are good for

locations, but not measuring distance

Map design principles

Contrast, figure ground separation, legibility, visual hierarchy, balance

Contrast

lets you distinguish the differences between items on a page

Figure ground separation

lets you distinguish the element in focus from the background

Legibility

being able to see symbols, and understand them

Visual Hierarchy

Layering information with the most important on top

Balance

organization of map and other elements on the page

TALDOGS

Title, author, legend, date, orientation, grid, scale

color ramp

ranges of colors. avoid red and greens and too many dark shades

Plainimetric Map

general reference map

thematic map

a map that shows a particular theme, or topic

Choropleth

data sorted into zones to show themes of interest. boundaries chosen not by data

Area class map

data sorted into zones but data determines polygons

Isopleth

joins points of equal value

Large scale map

Small area, large detail

Small scale map

Large area, small detail