Chapter 6

Question 1

geographic coordinate system

Answer 1

latitude and longitude, defines locations on the curved surface of the earth

Question 2

spheroid

Answer 2

aka ellipsoid. Mathematical model that approximates the irregular shape of the earth using two axes

Question 3

geoid

Answer 3

measure of earth’s radius

Question 4

datum

Answer 4

provide the optimal fit between the spheroid and geoid. described how a model fits into reality

Question 5

map projection

Answer 5

used to represent the earth on a flat surface

Question 6

projected coordinate system

Answer 6

defines locations on a flat map based on x,y coordinates

Question 7

conformal projections

Answer 7

preserve shape

Question 8

equal area projections

Answer 8

display area at proper relative size

Question 9

equidistant projections

Answer 9

preserve scale and distance

Question 10

azimuthal or true direction

Answer 10

maintain accurate directions

Question 11

map units

Answer 11

latitude and longitude values shown in decimal degrees

Question 12

on-the-fly projection

Answer 12

displaying data in one projection as if it were in another projection. The new projection is used for display and query purposes only, actual data is not altered.

Question 13

false easting

Answer 13

the linear value added to all x coordinates of a map projection so that none of the values in the geographic region being mapped are negative

Question 14

false northing

Answer 14

the linear value added to all y coordinates so that none of the values are negative

Question 15

datum transformation

Answer 15

a transformation definition that is used to transform the coordinates of a point defined in one datum to coordinates of a different datum

Question 16

georeferencing

Answer 16

align a map to a known coordinate system