georeferencing and spatial mapping

Question 1

spatial referencing systems

Answer 1

georeferencing: principles and process of transforming spatial data from an arbitrary system into a geographic or projected system
- aka: registration, coregistration, geometric transformation

Question 2

ellipsoid

Answer 2

when sphere parameters (a) is not equal to (b) - accounts for shape and buldge and earths rotation

Question 3

name some official ellipsoids

Answer 3

WGS84
Australian
Everest

Question 4

why are there so many ellipsoids

Answer 4

existed before satellite technology - each country used the North American Datum 1927 (NAD27)

Question 5

geoid

Answer 5

accurately represents the earths shape and size
based on equipotential gravity surfaces at mean sea level
rock densities cause the geoid to deviate from the ellipsoid

Question 6

Datum

Answer 6

measurements taken on the earths surface
raw measurements “levelled” to a geoid

Question 7

draw geographic coordinate systems

Answer 7

slide 10

Question 8

projected coordinate systems

Answer 8

Involves determining the locations of features on the Erths curved surface and then transforming these location info positions on a flat map

Question 9

2 issues involved in PCS

Answer 9

what type of curved surface is the earth
how to represent the curved surface of the earth in a plane

Question 10

representing the curved surface of the earth on a flat surface

Answer 10

1. when the surface is PLANE (azimuthal projections)
2. when the surface is CYLINDER (cylindrical projections)
3. when the surface is CONE (conic projections)

Question 11

how do map projections distort the earth?

Answer 11

1. accurate transformation of ANGLES (conformal or orthomorphic projections)
2. accurate transformation of AREAS (equal-area or equivalent projections)
3. accurate transformations of DISTANCES (equdistant projections)
4. accurate transformation of DIRECTIONS (azimuthal and gnomonic projections)

Question 12

UTM system

Answer 12

• UTM is a world-wide system defined in meters
  the world is divided into 60 zones, 6 degrees of longitude each, from 84N - 80S latitude
  each zone divided by a central meridian and equator

Question 13

lat/long to decimal degrees

Answer 13

slide 17

Question 14

cartography (fisher)

Answer 14

involved with the graphic communication of spatial relationships and distributions and includes the analysis and manipulation of geographic data to enhance representation

Question 15

cartography (intl catographic assn)

Answer 15

art, science, and technology of producing, using and studying maps

Question 16

maps

Answer 16

primary output of GIS analysis
scaled representation or model of geographic reality portrayed using a selected set of features on a flat medium

Question 17

map scale

Answer 17

defines the ration b.w distance on a map and corresponding distance on ground

Question 18

fractional scale

Answer 18

numerical expression

Question 19

verbal scale

Answer 19

written

Question 20

graphic scale

Answer 20

calibrated bar or line

Question 21

generalization

Answer 21

process of choosing which features to represent on the map and how they will be represented

classification
simplification
exaggeration
symbolization
induction

Question 22

classification

Answer 22

expressing the key characteristics of a distribution

Question 23

simplification

Answer 23

determining important characteristics if feature attributes and elimination of non-important ones

Question 24

exaggeration

Answer 24

enlarging or altering the features in order to capture the real-world importance

Question 25

symbolization

Answer 25

assigning graphic marks on the maps to features from the real world

Question 26

induction

Answer 26

making inferences on relationships among features on the map

Question 27

map design hierachy

Answer 27

target audience
map components
arranging features
= spatial data

Question 28

types of spatial maps

Answer 28

simple choropleth maps: used to visualize tabular statistics geogrpahically and compare magnitudes in various places
classless choropleth map: ration-scale portrayal of the attribute value and represent a clear pic of the existing complexity of the geographic space

Question 29

procedure for creating choroplethic maps depnds on

Answer 29

size and shape of unit areas
number of classes (6 or 7)
class limit determination

Question 30

components of a good map

Answer 30

map title
legend
north arrow
scale
labels and text