1What is the main purpose of a map projection?
To portray the spherical surface of the Earth on a flat two-dimensional surface
2What does a map projection transform the Earth from and to?
From a 3D spherical shape to a 2D planar shape
3What is a Coordinate Reference System (CRS)?
A system that defines how a two-dimensional projected map in GIS relates to real places on Earth
4What factors influence the choice of a map projection and CRS?
The regional extent of the area, the analysis to be performed, and the availability of data
5Why are globes not always practical for GIS mapping?
They are difficult to carry and are convenient mainly at extremely small scales
6Why are map projections needed instead of globes?
Because cartographers need to represent the spherical Earth on a practical flat surface
7What is an important consideration when choosing a map projection?
The scale and purpose of the map
8Can one map projection be suitable for every area and purpose?
No, each projection has advantages and disadvantages
9What are the three families of map projections?
Planar, cylindrical, and conical
10What is a planar projection?
A projection created by projecting the Earth onto a flat surface
11What is a cylindrical projection?
A projection created by surrounding the globe with a cylindrical surface
12What is a conical projection?
A projection created by surrounding the globe with a cone
13How are modern map projections created?
Using mathematical principles of geometry and trigonometry
14Are map projections absolutely accurate representations of the spherical Earth?
No, every map projection contains some distortion
15What three characteristics can be distorted by map projections?
Angular conformity, distance, and area
16What is a compromise projection?
A projection that accepts some distortion in several properties to provide an overall useful representation
17What are two examples of compromise projections?
Winkel Tripel and Robinson
18What is the Robinson projection?
A compromise projection where distortions of area, angular conformity, and distance are kept within acceptable limits
19Why is it usually impossible to preserve all map characteristics simultaneously?
Because projecting a spherical surface onto a flat surface necessarily introduces distortions
20What should you consider when selecting a projection for accurate analysis?
Choose a projection that provides the best characteristics for the specific analysis
21What type of projection should be used when accurate distance measurement is needed?
An equidistant projection
22What is a conformal projection?
A projection that preserves angular relationships
23What is another name for a conformal projection?
Orthomorphic projection
24When are conformal projections useful?
When preservation of angular relationships is important
25What are common uses of conformal projections?
Navigation and meteorological tasks
26What is a disadvantage of conformal projections?
They distort areas
27What happens to area measurement accuracy with conformal projections as the mapped area becomes larger?
Area measurements become less accurate
28What are two examples of conformal projections?
Mercator and Lambert Conformal Conic
29What does the Mercator projection preserve?
Angular relationships
30What does the Mercator projection distort?
Areas
31What type of projection is commonly used by the U.S. Geological Survey for many topographic maps?
A conformal projection
32What is an equidistant projection?
A projection designed to preserve distances accurately
33What must be kept constant in an equidistant projection?
The scale of the map
34What does an equidistant map correctly represent?
Distances from the center of the projection or along specified lines
35What are equidistant projections used for?
Radio mapping, seismic mapping, and navigation
36What are two examples of equidistant projections?
Plate Carree Equidistant Cylindrical and Equirectangular
37Which projection is used for the emblem of the United Nations?
Azimuthal Equidistant projection
38What is an equal area map?
A map where all mapped areas maintain the same proportional relationship to the areas they represent on Earth
39When are equal area projections most useful?
When calculations of area are the dominant analysis
40Why are equal area projections useful for analyzing large areas?
They provide more precise area measurements
41What is a disadvantage of equal area projections?
They distort angular conformity, especially over large areas
42What happens to angular distortion in small areas using equal area projections?
Small areas are far less prone to angular distortion
43What are examples of equal area projections?
Albers Equal Area, Lambert Equal Area, and Mollweide Equal Area Cylindrical
44Why are there hundreds of map projections?
Different projections are designed to portray different portions of Earth's surface as faithfully as possible
45Why are map projection choices sometimes determined by the country?
Most countries have commonly used projections and data exchange often follows the national trend
46What are the two main types of Coordinate Reference Systems?
Geographic Coordinate Reference Systems and Projected Coordinate Reference Systems
47What are projected coordinate reference systems also called?
Cartesian or rectangular coordinate reference systems
48What does a CRS allow every place on Earth to be specified by?
A set of coordinates
49What does a Geographic Coordinate Reference System use to describe locations?
Degrees of latitude and longitude, and sometimes height
50What is the most popular Geographic Coordinate Reference System mentioned in the text?
WGS 84
51What are lines of latitude?
Lines that run parallel to the equator
52What does the equator represent in the geographic coordinate system?
The reference line for latitude
53How many degrees of latitude are in each hemisphere?
90 degrees
54How is latitude measured in the Northern Hemisphere?
From 0° at the equator to 90° at the North Pole
55How is latitude measured in the Southern Hemisphere?
From 0° at the equator to 90° at the South Pole
56How are southern latitudes often represented in digital mapping?
As negative values from 0° to -90°
57What is the distance between lines of latitude?
60 nautical miles
58What are lines of longitude?
Lines that run perpendicular to the equator and converge at the poles
59What is the reference line for longitude?
The Prime Meridian
60Where does the Prime Meridian pass?
Through Greenwich, England
61How is longitude measured?
From 0° to 180° east or west of the Prime Meridian
62How are western longitudes often represented in digital mapping?
As negative values
63At what location is one degree of longitude equal in distance to one degree of latitude?
At the equator
64What happens to the distance between lines of longitude toward the poles?
It progressively decreases
65What happens to all 360° of longitude at the exact poles?
They converge at a single point
66How many minutes are in one degree?
60 minutes
67How many seconds are in one minute?
60 seconds
68How many seconds are in one degree?
3,600 seconds
69At the equator, what distance does one second of latitude or longitude represent?
30.87624 meters
70What are the two axes of a two-dimensional projected CRS?
X and Y
71How are the X and Y axes positioned?
At right angles to each other
72What does the XY-plane represent?
A two-dimensional coordinate system
73What additional axis is added to a three-dimensional CRS?
The Z-axis
74What does the Z-axis represent?
The third dimension of space
75What can every point expressed in spherical coordinates be expressed as?
An XYZ coordinate
76What direction do Y-values increase in a projected CRS in the Northern Hemisphere?
Northward
77What direction do X-values increase in a projected CRS in the Northern Hemisphere?
Eastward
78What direction do Y-values increase in a projected CRS in the Southern Hemisphere according to the text?
Southward
79What direction do X-values increase in a projected CRS in the Southern Hemisphere according to the text?
Westward
80What is UTM?
Universal Transverse Mercator
81What type of CRS is UTM?
A global projected coordinate reference system
82Where is the origin of the UTM coordinate reference system?
On the equator at a specific longitude
83Why is the world divided into UTM zones?
To minimize distortion
84How many UTM zones are there?
60
85How wide is each UTM zone in longitude?
6 degrees
86How are UTM zones numbered?
From 1 to 60
87Where does UTM zone numbering begin?
At the antimeridian at 180° West
88In which direction does UTM zone numbering progress?
Eastward
89What does the S mean in a UTM zone such as 35S?
The zone is south of the equator
90What information is needed to indicate a UTM coordinate south of the equator?
The zone number, northing value, and easting value
91What is northing?
The distance of a position from the equator in meters
92What is easting?
The distance from the central meridian of the UTM zone
93What is a central meridian?
The longitude used as the central reference meridian of a UTM zone
94What is the false northing value used in the Southern Hemisphere UTM system?
10,000,000 meters
95What is the false easting value used in the UTM system?
500,000 meters
96Why is a false northing value used in the Southern Hemisphere?
To avoid negative northing values
97Why is a false easting value used in UTM?
To avoid negative easting values
98Which UTM zone is used for the Area of Interest in the example?
UTM zone 35S
99What is the central meridian of UTM zone 35S in the example?
27° East
100If a point is 3,550,000 m south of the equator, what is its unadjusted northing?
-3,550,000 m
101What is the adjusted northing for a point 3,550,000 m south of the equator?
6,450,000 m
102How is the adjusted northing calculated?
-3,550,000 m + 10,000,000 m = 6,450,000 m
103If a point is 85,000 m west of the central meridian, what is its unadjusted easting?
-85,000 m
104What is the adjusted easting for a point 85,000 m west of the central meridian?
415,000 m
105How is the adjusted easting calculated?
-85,000 m + 500,000 m = 415,000 m
106How is the example UTM 35S coordinate written?
35 415,000 m E / 6,450,000 m N
107What is On-The-Fly Projection?
A GIS functionality that automatically displays layers in a chosen projection even when they use different coordinate reference systems
108Why is On-The-Fly Projection useful?
It allows layers with different CRSs to be overlaid in the same map window
109What does QGIS do with On-The-Fly Projection?
It applies the functionality by default
110What problem does On-The-Fly Projection solve?
It allows differently projected layers to appear together correctly in the map window
111What can happen if layers have different coordinate reference systems without appropriate projection handling?
They may appear in totally different areas of the map window
112What is an example of layers with different CRSs?
A UTM 35S boundary layer and rainfall points in WGS 84
113Do GIS users always need to create a new CRS?
No, most GIS data already come with a defined CRS
114Do GIS users always need to reproject their data?
No, usually the data are already projected appropriately
115Why is understanding map projections and CRSs still useful?
It helps users understand how spatial data are positioned and represented in GIS
116What does a map projection do to the Earth's surface?
It represents the Earth's surface on a flat two-dimensional surface
117Why are most map projections optimized for smaller areas?
Because larger areas generally experience greater distortion
118What are the three characteristics that cannot all be preserved simultaneously by map projections?
Angular conformity, distance, and area
119What does a Coordinate Reference System define?
How coordinates relate a two-dimensional projected map to real locations on Earth
120What are the two types of CRS?
Geographic Coordinate Systems and Projected Coordinate Systems
121What does On-The-Fly projection allow GIS users to do?
Overlay layers even when they use different coordinate reference systems