Basic Knowledge

Question 1

longitude

Answer 1

East to west, lambda, 180 to -180

180/-180 is international date line
0 is prime meridian

Question 2

Latitude

Answer 2

North to south, 90 to -90, phi,

90 is North Pole

Question 3

Horizontal Datum

Answer 3

Relative position of a point on a surface - geometric relationship between a grid system and the earth’s surface

WGS84 is an example

Question 4

Plane coordinate transformations

Answer 4

Change the way data is projected on a flat map

Question 5

Similarity transformation

Answer 5

Plane transformation where 2 sets of points only differ in scale, rotation and offset

Question 6

Affine transformation

Answer 6

Plane transformation that is also used for differences in scale, rotation, offset - useful for satellites that orbit in s shapes

Question 7

Second-order polynomial transformation

Answer 7

Plane transformation that corrects data sets that are skewed in many ways

Question 8

Graticule

Answer 8

Spherical grid. When put flat on a map, it is a projected graticule

Question 9

UTM coordinate system

Answer 9

Universal Transverse Mercator
Written in (eastings, nothings)
Latitudes higher than 84 degrees N and 80 degrees S are excluded
Uses transverse Mercator projection
Split in 60 UTM zones that are like orange slices
Each UTM zone has 2 standard lines where the scale is uniform

Question 10

SPC

Answer 10

State plane coordinate systems
Lines are parallel and don’t converge
Used to reference large scale mapping projects
Made up of 124 zones that cover 50 stats
E-W zones use lambert conical conformal projection
N-S zones use transverse Mercator
Max error of 1 in 10000
Only positive x/y values bc of false origins
Conformal

Question 11

Distortion ellipses

Answer 11

Help visualize what type of distortion occurred with a specific type of map projection

Question 12

Equivalence

Answer 12

A geometric property of a projection method - means the projection maintained equal areas (but not necessarily scales or distances)

Question 13

Conformality

Answer 13

A geometric property of a projection method - distortion ellipses are not the same size but are same shape

• angle measurements are consistent
• SPC is conformal

Question 14

Equidistance

Answer 14

A geometric property of a projection method - distances are accurate radiating from one or two points

Question 15

Azimuthal

Answer 15

A geometric property of a projection method - azimuths (directions) are maintained from one or two points to every other point

Question 16

Compromise Geometric Property

Answer 16

No properties are preserved but instead distortion of the map is reduced

Question 17

Planar projection

Answer 17

Usually centered on a pole
Circular, lots of distortion towards edges
Azimuthal straight convergent meridians, parallels form concentric circles

Question 18

Conic projection

Answer 18

Straight meridians that converge to a single point at poles
Parallels form concentric arcs
SPC zones that are E-W use this

Question 19

Pseudocylindric projection

Answer 19

Similar to cylindrical projection but meridians are curved and converge at top and bottom

Question 20

Cylindric projection

Answer 20

Straight meridians and parallels that intersect at right angles
UTM is cylindric
Most distortion at N and south poles
(If the higher degrees of latitude were not excluded there would be infinite distortion at the poles themselves)