GIS Exam One

Question 1

What are the components of GIS?

Answer 1

People, software, data, hardware, and approaches

Question 2

What does compilation mean?

Answer 2

The process of creating a GIS database by capturing and managing geographic data

Question 3

What is spatial analysis?

Answer 3

The ability to evaluate a problem based on its spatial and related non spatial characteristics, its what separates GIS from desktop mapping (ex. query by location)

Question 4

Where was GIS first developed?

Answer 4

North America, Roger Tomlinson “Father of GIS”

Question 5

What is discrete data?

Answer 5

Values that change abruptly from one category to another

Question 6

What is Continuous data?

Answer 6

Values vary continuously with no abrupt or sharp boundaries

Question 7

What is In situ?

Answer 7

The process of collecting real world data on the ground using specialized instruments (ex. Census, land surveying, digitization scanning, or remote sensing)

Question 8

What are the three main types of sampling and their definitions?

Answer 8

1. Random Sampling: every member of the population has an equal chance of being selected
2. Systematic Sampling: population members are listed in order and individuals are chosen at regular intervals
3. Stratified Sampling: the population is divided into meaningful subgroups and a decision is made on how many people should be sampled from each subgroup, using a random or systematic method to select the sample

Question 9

What is digitization?

Answer 9

The process of converting coordinates from a map, image, or other source to a digital format

Question 10

Define the process of digitizing.

Answer 10

→ Map Preparation: assigning unique identifiers, ensuring the continuity of features, registrations/tablet coordinates, and control points
→Coordinate Transformation: when x,y coordinates are recorded on a tablet, their values are the tablets coordinates not real world ones, its the process of converting tablet coordinates to real world coordinates

Question 11

What are the three segments of GPS?

Answer 11

1. Space: comprised of 27 satellites
2. Control: owned by US Department of Defense
3. User: applications like marine navigation, recreations, or vehicle tracking

Question 12

What is remote sensing?

Answer 12

The art and science of collecting information about earth features and phenomena using sensors without physically coming in contact with the object of interest (active: emits its own energy [radar]. Passive: does not emit its own energy, but detects energy from the sun [satellites])

Question 13

What are SQL operators combination?

Answer 13

Ex. (land use = urban) and mill rate = B)
you can have no results (its possible that the query doesn’t work)

Question 14

What is resolutions and its attributes?

Answer 14

It refers to the level of detail provided by the imagery.
1. Spectral (number and size of wavelength intervals remote sensing can detect)
2. Spatial (measure of smallest separations between two objects that can be resolved by a sensor)
3. Radiometric (sensitivity of a remote sensing instrument to differences in signal strength as it records energy)
4. Temporal (describes how often the remote sensing instrument records imagery of a certain portion of the earth)

Question 15

What is a Vector?

Answer 15

Made up of points (0D), lines (1D), and polygons (2D). Relies on the use of coordinates and is most effective for storing and analyzing discrete data. Smaller file that raster.

Question 16

What is a Raster?

Answer 16

Made up of cells (pixels). Its only two dimensions and is most effective for storing and analyzing continuous data. Large file. Only one value is allowed per cell.

Question 17

Define the Spaghetti Model

Answer 17

Vector data structure characterized by the fact that there is no encoded relationship between points, lines, and polygon. It only encodes absolute location. Issues with this model include endpoints that don’t meet and sliver polygons.

Question 18

What is Topology?

Answer 18

It describes the type of spatial relationships that exist between geographic features. It includes four relationships.
1. Containment: features contained within other features
2. Adjacency: link between contiguous features (they share at least one common boundary)
3. Proximity: ordinal indication of distance, link between features based on their location
4. Connectivity: adjacency to a network, must follow a path of linked nodes (ex. when you search how far something is from your house)

Question 19

What is the topological model?

Answer 19

A data model where spatial relationships between geographic features/files is explicitly recorded (encoding relationships)

Question 20

What is map design?

Question 21

What are the main map elements?

Answer 21

→

Question 22

What are the visual variables of maps?

Answer 22

→ Color: Hue
→ Values: light or dark versions of hue
→ Saturation: how much a color is of its true hue
→ Shapes: symbols that represent specific things
→ Size: representation of quantitative data
→ Nominal: names
→ Ordinal: something you can list (ranking)
→ Numerical: ratios and intervals

Question 23

What is visual hierarchy and any attributes associated with it?

Answer 23

The perceptual, cognitive contrast of cartographic elements so that they appear to lie in an ordered set of layers of increasing importance as they are seen (ex. countries with a larger bolder font are meant to be seen compared to states with a small font

Question 24

What is equal interval?

Question 25

Define quantiles.

Question 26

What are natural breaks?

Question 27

Define geovisualization.

Answer 27

Direct depiction of movement and change. Such as interactive maps or mixing maps with graphics and sound.

Question 28

What is an Ellipsoid?

Answer 28

Earth that is slightly flattened due to the earth rotating on its axis.

Question 29

What is a Geoid?

Answer 29

Model of global mean sea level that is used to measure precise surface elevations (it defines zero elevation). Somewhat mathematically lumpy shape.

Question 30

What is a Datum?

Answer 30

Based on an ellipsoid, it allows you to log points on an ellipsoid. It provides a base elevation for mapping. Defined in terms of origin, orientation, shape, size, and type.

Question 31

What is a map projection?

Answer 31

A map projection is the systematic transformation of a 3D surface onto a 2D surface (it does result in distortion of some areas in regards to distance, direction, or shape).

Question 32

What are the main properties of 3D map projections?

Answer 32

1. Tangent: 2. Secant: the projection surface intersects the globe (intersection line forms a circle), no distortions along the circle, distortion increases away from the standard line 3. Standard line: essentially the equator on a equatorial, on a cone its a meridian 4. Standard point/line: standard parallel (the lines of longitude and latitude)

Question 33

What are the characteristics of a 2D CONFORMAL projection (Lambert)?

Answer 33

They preserve shape of small areas, most often used on large scale maps to measure direction. If the map latitudes and longitudes don't meet at 90 degrees then it is not a conformal projection.

Question 34

What are the characteristics of a 2D EQUIVALENT map projection (Albers)?

Answer 34

They preserve the property of size (things maintain proportionality). Used when the relative size of objects is important (ex. a choropleth map)

Question 35

What are the characteristics of a 2D AZIMUTHA map projection?

Answer 35

Preserves the direction from one location. True direction means that the straight line connecting any two points on the map is the same direction as the direction a compass would show.

Question 36

What are the characteristics of a 2D EQUIDISTANT projection?

Answer 36

It preserves distance but only along one or a few directions between locations, useful when the correct representation of relative distance is important.

Question 37

What are the characteristics of a 2D COMPROMISE map projection?

Answer 37

It does not preserve any property but minimizes distortion, most often used for very small scale maps.

Question 38

What are spherical coordinates?

Answer 38

Spherical coordinates may be difficult to use because they are decimals, they are inconvenient for spatial measurements

Question 39

Define the Cartesian coordinate system

Answer 39

X,Y coordinate system, easy to comprehend, axis are perpendicular, and units can be in meter, feet, etc

Question 40

What is the Universal transverse mercator?

Answer 40

Allows you to locate any point on the earth. Divides the earth in horizontal zones of 6 degrees.

Question 41

Define Nominal (categorical) data.

Answer 41

Data measure according to their qualitative characteristics, which allow for the formation of sub groups with no implied order. Subgroups do not overlap and only uses = or ≠. Examples include: names of countries or employment classifications

Question 42

Define Ordinal data.

Answer 42

Data are ranked according to quantitative characteristics or in order of importance. Used to measure things like satisfaction, discomfort, or happiness Operations include: =, ≠, <, >

Question 43

Define interval data.

Answer 43

Measured according to their quantitative value using a numerical scale, intervals between values are uniform but that value of 0 is arbitrary (0 does not imply the absence of) Operations include: =, ≠, <, >, +, -

Question 44

Define ratio data.

Answer 44

Measured according to their quantitative value using a numerical scale, intervals between values are uniform and the value of 0 is not arbitrary (0 implies the absence of something) Operations include: /, *, =, ≠, <, >, +, -

Question 45

What are the differences between a database and DBMS?

Answer 45

A database is an organized collection of data managed by a DBMS. A DBMS is a computer program used to add, edit, query, analyze, and report information regarding attributes of data contained in the database

Question 46

What is a relational database?

Answer 46

A structure composed of several tables that are linked together through a defined relationship using unique identifiers

Question 47

Characteristics of Relating tables

Answer 47

1. Source Table: contains the information to be appended 2. Destination Table: receives the appended information 3. Cardinality: describes the relationship between each table

Question 48

What are joining tables?

Answer 48

A relational DBMS process used to establish a temporary relationship. Includes only "one to one" and "many to one" when joining.

Question 49

What is a data query?

Answer 49

Functionality for selecting a subset of features or computing a new characteristic.

Question 50

What is a thematic (attribute) query?

Answer 50

Operates on the table, selection of features is based on their spatial characteristics using DBMS.

Question 51

SQL (Structured Query Language)

Answer 51

A language used to query data in a database (typically DBMS). - SQL operators 1. Logical: =, <, >, ≧ 2. Boolean: and means intersects, or means either 3. Other: wildcards (%,*) for partial string searches, using like instead of the = sign, null

Question 52

Define spatial query.

Answer 52

A logical expression that selects geographic features based on their location or specified spatial relationship. Select by location.

Question 53

Define spatial join.

Answer 53

It appends the attributes of one layer to another layer based on their spatial relationship. (ex. lines to polygons, points to points). Select by attribute.