Midterm Review Flashcards

1
Q

What is GIS?

A

GIS is an information system used to manipulate, summarize, query, edit, and visualize spatial and non-spatial information stored in a computer database.

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2
Q

The GIS Process: six processes:

A

1) Physical world, 2) define GIS Protocol 3) Collect spatial and non spatial data, 4) Data analysis and edit, 5) Report the results, and 6) Take action and make policy

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3
Q

GIS applications in many fields:

A

1) typhoon/ hurricane monitoring, map the hyphone track and know where the most affected
areas are.
2) population migration, map the population flow from the origin country to the destination
country.
3) fire evacuation, map the fire evacuation routes in the fire incidence
4) disaster management……
5) endangered species protection

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4
Q

Farther of GIS:

A

Roger Tomlinson

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5
Q

Founder of GIS Harvard Laboratory:

A

Howard Fisher

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6
Q

Founder of ESRI:

A

Jack and Laura Dangermond.

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7
Q

Is a paper map a GIS? Why or why not?

A

Paper map: a static map. Cannot zoom in and zoom out. Cannot do a spatial analysis. It is not a computer-
based system. Can be used as a base for GIS though.

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8
Q

Which GIS software do you use in our lab class? How does this GIS software different from most other software.

A

We use ArcGIS Pro 2.9 for the class. We do not use ArcGIS Desktop

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9
Q

Vector data:

A

Points, lines, and Polygons, include topology.

Advantages: 1) compact data structure, 2) topology, perform the network analysis 3) used in discrete features, points, polylines, polygons, preserve the spatial accuracy of these discrete features.
Disadvantages: 1) it is a complex data source; 2) for the topology, we have to consider the connectivity between the neighboring polygons; 3) is not efficient to represent the continuous feature (elevation)

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10
Q

File formats for vectors:

A

Coverage (retired), Shapefile, ArcGIS Geodatabse (.gdb), enterprise Geodatabase (.ArcSDE) KML/KMZ are google maps and google Earth. XY units are used for map data.

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11
Q

Which is most commonly used geodatabse in ArcGIS and our class?

A

File Geodatebase (.gdb)

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12
Q

Shapefiles (what are mandatory files?), multiple files with same name but different extensions

A

1) .shp (geometry information); 2) .dbf (attribute information); 3) .shx (index information).

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13
Q

Raster data

A

(cells = grids, cell size= spatial resolution, JPEG, TIFF, PNG files are all raster data) (Also smaller cell size means higher spatial resolution) No topology

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14
Q

Vector data (pros and cons) and raster data (pros and cons)

A

Vector format also allows for complex spatial analysis and operations, as well as requiring less storage space than raster format for the same level of detail. However, it can be difficult to represent continuous phenomena, such as elevation or temperature, and is prone to topological errors like gaps and overlaps. (Reverse these for Raster)

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15
Q

Conversion between vector and raster data:

A

do not convert many times (maximum 2 times)

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16
Q

Data Type (Most numbers are ratio, interval is basically just temp and elevation)

A

(1) Temperature: it does not have the meaning zero, interval data
(2) Elevation: it does not have the meaningful zero, interval data
(3) Population: it does have the meaningful zero; ratio data
(4) Building Name: nominal data
(5) City size: small, medium, and large; ordinal
(6) Hurricane type: tornado, typhoon, hurricane, categorical data

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17
Q

Qualitative thematic maps: does not tell the magnitude of the variables.
Which are used for Nominal/Ordinal/categorical?

A

(1) Nominal, use the single symbol map and turn on the labeling of the field
(2) Categorical, use the unique values map
(3) Ordinal, use the unique values map

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18
Q

Graduate color maps or choropleth maps:

A

relative data (proportion, percentage, ratio)

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19
Q

Bivariate color maps or bivariate choropleth maps:

A

display two variables on one map (relative data)

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20
Q

Graduated symbol maps:

A

absolute data; both positive and negative absolute data, classified for the data

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21
Q

Proportional symbol maps:

A

absolute data: positive absolute data, unclassified or classified data works

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22
Q

Pie chart:

A

multiple variables (of the same categories): absolute data and relative data

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23
Q

Dot density maps:

A

show population data : absolute data

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24
Q

Cartogram maps:

A

not available in ArcGIS Pro. Prioritize the specific theme over the spatial accuracy.

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25
Q

What are required elements in a map layout?

A

1) Title 2) scale bar 3) legend 4) north arrow

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26
Q

What are optional elements in a map layout?

A

1) Author name 2) date 3) data source 4) explanatory text 5) coordinate system

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27
Q

What should a title have?

A

do not use the abbreviations, include geographic regions and unit, do not use Map in the title, always be largest on the map

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28
Q

Scale:

A

use easy number to represent scale on the map. 1: 300 vs. 1:317

Also remember population is absolute, use graduated symbol map

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29
Q

When to use North Arrow vs. Graticule?

A

North arrow is used in 2 D mapping and analysis (CS is in PCS)
Graticule is sued in 3 D globe (CS is in GCS)

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30
Q

The best approximation of the earth is:

A

Ellipsoid

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31
Q

Datum:

A

Make the best fit between the ellipsoid and the earth surface

32
Q

Different datums in the world?

A

Only the datums that pass through local areas in question can provide an accurate coordinate for use

33
Q

Two types of datums

A

Local datum and Geocentric datum

34
Q

NAD 27, what type of datum is it? Who made it and when, where does it originate?

A

Local datum, Ellipsoid: Clarke 1866; origin: meades’ ranch, Kansas

35
Q

NAD 83

A

Local datum, Ellipsoid: GRS 1980, origin: 2 meters away from earth center

36
Q

WGS 84

A

(geocentric datum (global datum), Ellipsoid: WGS 84, origin: earth center)

37
Q

What causes the shifts between datums?

A

Datums start from different origins, direction between first points to second, third….. different orientations.

38
Q

Why is it important to choose the correct datum for a coordinate system?

A

Using the wrong datum will result in a different coordinate system than intended due to the shift of hundreds of meters.

39
Q

Components of the datum:

A

1) selected ellipsoid
2) origin
3) direction from the first to second to third points
4) orientation

40
Q

GCS components: (What’s on a globe?)

A

a. Latitude (y) (0 to 90, (0-90N) degree and (0 -90S), the latitude is not equal, at the equator, the latitude is the largest, then become small towards the north/south pole.
b. Longitude (X, -180 to 180, 180 W to 180 E)
c. Equator (y = 0)
d. Prime Meridian ( x = 0)
e. Decimal Degrees (DD), Degrees Minutes Seconds (DMS)

41
Q

Geographic coordinate system (GCS)

A

Gives you a globe, you can point out the equator, prime meridian, latitude, and longtuide.

42
Q

Allowable coordinates

A

-180 to +180, 180 W to 180 E
-90 to + 90, 90 S to 90 N

43
Q

To create a map projection, we have to use a pyramid, five steps:

A

Earth – Ellipsoid – Datum – Geographic Coordiante System (GCS) – Projected Coordiante System ( PCS)

44
Q

Three shapes of map projection:

A

cylincal, conic, athmathal (planar) map projections

45
Q

Two cases:

A

Tangent (one standard line) case, Secant (two standard lines) case

46
Q

Standard line(s), standard circle:

A

no distortion along the standard line or circle.

47
Q

Aspect:

A

Normal, transverse (90 degree rotation), and oblique (Any other rotation)

48
Q

Distortions:

A

four properties will be distorted: size, shape, distance, direction.

49
Q

Lambert Conformal Conic

A

(preserve west-east orientation)

50
Q

Universal Transverse Mercator

A

(preserve north-south orientation)

The UTM system consists of 60 zones, each 6-degrees of longitude in width.

51
Q

What PCSs are used in State Plane Coordinate Systems?

A

(some states use Lambert, some states use UTM, some use both
(such as Florida), and some use three systems (Alaska, use Lambert conic, UTM and oblique Mercator)

52
Q

What does a GCS do and how is a PCS different in its purpose?

A

A GCS defines where the data is located on the earth’s surface. A PCS just tells the data how to draw on a flat surface, like on a paper map or a computer screen

53
Q

How to select appropriate map projections? (The method by which a map is altered to display as a flat image)

A

choose a projected coordinate system in which the places and properties that are most important to your map are the least distorted.

54
Q

Projection vs. Project?

A

Projection: when the layer has no coordinate system

Project: Convert the CS for the layer from one to another, is applied to the layer with coordinate system.

55
Q

Which continent has the positive x and y coordinates in NAD 1983 Oregon State Lambert map projection?

A

South Africa

56
Q

What is a developable surface?

A

The surface that the map projection touches or cuts through the ellipsoid

57
Q

What are the most common shapes for a developable surface?

A

Cylinder, Cone, Planar

58
Q

Describe the State Plane coordinate system

A

This is the coordinate system used in 50 states in the U.S. Each state can have different map projections based on the orientation of state.

59
Q

What types of projections are used in a State Plane coordinate system?
(Remember N-S and W-E, and the alternative when neither apply, which state takes 3? What’s the other exception?)

A

If the state has the N-S orientation, it uses UTM Mercator map projection. If the state has the W-E orientation, it uses lambert conformal conic map projection. If the state is not in the W-E or N-S orientation, it uses oblique Mercator map projection. Some states use two map projections and Alaska use three map projections because it has many different orientations for the islands.

60
Q

Describe the Universe Transverse Mercator (UTM). What units is it measured in, how many units in US?

A

It is a global map projection, and it is a cylindrical map projection. It divided the world into 60 zones, and each zone is 6 degrees. If the area is in the north hemisphere, it will be the zone number + N; but if the area is in the south hemisphere, it will be written as the zone number + S. For the U.S, it spans 10 UTM zones from UTM zone 10N to UTM zone 19N.

61
Q

What are the UTM zones used in Florida?

A

UTM zone 16 N and 17 N.

62
Q

Which Florida UTM zone is more generally applicable?

A

UTM 17 N, the majority of the state is in it.

63
Q

What is the map projection?

A

Map projection is a 2D coordinate system. It is converted based on the 3D coordinate system. Representing a 3d space on a 2d plane.

64
Q

How is a map projection similar to a GCS?

A

1) GCS and PCS both are coordinate systems, and they both can used to represent geographic locations.
2) They both need to model the earth and use the ellipsoid to represent the earth shape
3) They both are based upon the datum

65
Q

How is a map projection different from a GCS?

A

1) GCS is a 3D coordinate, but PCS is a 2D planar coordinate system
2) GCS only provides limited view of the study area, but PCS provides detailed view of the study area.
3) GCS uses degree (DD or DMS) as unit, but PCS uses linear units such as miles, meter, feet, ect.

66
Q

How to select proper coordinate systems (GCS and PCS) in your final project or any GIS project?

A

If a project spans multiple PCS areas it should use a GCS, but if it is confined to a particular region it should use that regions PCS. Like the Gauss Conform System for South Africa. The most commonly accepted GCS is WGS84. It has around 2 cm of error and has become standard worldwide.

67
Q

If your mapping purpose is to preserve Area, use:

A

Equal area map projection.

68
Q

If your mapping purpose is to preserve Distance, use:

A

equal distance map projection.

69
Q

If your mapping purpose is to preserve Shape, use:

A

Conformal conic map projection.

70
Q

If your mapping purpose is to preserve Direction, use: (American sailors)

A

Mercator map projection.

71
Q

If your mapping purpose is to not preserve any particular properties but still want to minimize the overall distortion, use:

A

Robinson map projection, it’s a trade-off between all properties.

72
Q

If the study area is in N-S orientation, use:

A

UTM map projection

73
Q

If the study area is in E-W orientation, use:

A

Lambert conformal conic map projection

74
Q

If the study area is neither in the N-S nor E-W, use:

A

Oblique Mercator map projection

75
Q

USGS uses which coordinate system?

A

state plane coordinate system (SPCS)

76
Q

Google uses which coordinate system?

A

Mercator

77
Q

GPS uses which coordinate system?

A

WGS 1984