Coordinate Systems

Question 1

What does the Prime Meridian mark?

Answer 1

0 degrees longitude, the change between east and west longitude.

Question 2

Equator

Answer 2

0 degrees latitude

Question 3

In GIS X is for

Answer 3

Longitude

Question 4

In GIS Y is for

Answer 4

Latitude

Question 5

In GIS, what does Z represent?

Answer 5

Elevation

Question 6

Unprojected (geographic) coordinate systems are based on what, measured in what?

Answer 6

Based on spherical coordinates and measured in degrees of latitude and longitude.

Question 7

Projected coordinate systems convert what to what?

Answer 7

They convert spherical coordinates to planar coordinates.

Question 8

What do PCSs use?

Answer 8

Specific mathematical equations that convert 3D (spherical) coordinates to 2D (planar) coordinates.

Question 9

Latitude ranges from what degree to what degree?

Answer 9

90 degrees north (North Pole) to 90 degrees south (South Pole)

Question 10

What is the origin point (0 degrees longitude)?

Answer 10

Greenwich, England, where the Prime Meridian passes through.

Question 11

Unprojected data in a GCS is stored in:

Answer 11

Degrees.

Question 12

How many meters are represented by 0.001 degrees?

Answer 12

110 meters

Question 13

GCS refers to data that is measured in…

Answer 13

Degrees, minutes, and seconds

Question 14

PCS refers to data that is defined by a 2D surface and can be measured in…

Answer 14

Meters and feet.

Question 15

A PCS/map projection is always based on what?

Answer 15

A GCS /coordinate system.

Question 16

What is the primary use of GCS?

Answer 16

Data distribution. GCS are not desirable for maps/analysis because of distortion.

Question 17

Every map distorts at least one of what four things?

Answer 17

Shape, area, distance, direction.

Question 18

Map projection is a process of what?

Answer 18

Converting from a 3D surface to a 2D surface.

Question 19

A map can show one or more, but never all, of what?

Answer 19

True distances, true directions, true shapes, or true areas.

Question 20

The larger the area being mapped…

Answer 20

…the greater the amount of distortion.

Question 21

A conformal map does what?

Answer 21

Preserves local shape. Distorts area (most features are too large/small).

Question 22

What does an equivalent map preserve?

Answer 22

Area, features on the map are the same size relative to their size on the earth. Generally this distorts shapes.

Question 23

What does an equidistant map preserve?

Answer 23

True scale for all straight lines passing through a single specified point.

Question 24

An azimuthal projection is measured in what? And preserves what?

Answer 24

Measured in degrees of angle from north, preserves direction from point a to b.

Question 26

Another name for conformal map projection is?

Answer 26

Mercator projection.

Question 27

UTM stands for what?

Answer 27

Universal Transverse Mercator

Question 28

How is UTM different from latlong?

Answer 28

UTM divides earth into 60 zones and projects each to the plane as a basis for its coordinates.

Question 29

What does UTM use as a unit of measurement?

Answer 29

Meters.

Question 30

What are the common datums used in North America?

Answer 30

NAD83, WGS84, NAD 1927, and NAD 1983 HARN

Question 31

What location does 30W 30N represent?

Answer 31

30 degrees north of the equator and 30 degrees west of the Prime Meridian.

Question 32

What location does 15E and 15N represent?

Answer 32

15 degrees north of the equator and 15 degrees east of the Prime Meridian.

Question 33

If the coordinates in a PCS have a negative value for latitude and a positive value for longitude, what does that represent?

Answer 33

South of the equator, east of the prime meridian.

Question 34

Only use the **Define Projection Tool** when you need to…

Answer 34

Fix missing or incorrect CS.

Question 35

What tool is used to change a CS permanently?

Answer 35

Project tool.

Question 36

What tool is used to assemble collections of data with the same CS?

Answer 36

Project tool.