exam #1 Flashcards
(129 cards)
1
Q
what is geography
A
where things are and why things are where they are
2
Q
what’s GIS
A
study of using and understanding spacial data
3
Q
what’s geospatial technology, what 3 things does it include
A
high-tech systems that acquire, analyze, manage, store and/or visualize location-based data
- global positioning systems
- geographic information systems
- remote sensing
4
Q
what’s geodesy
A
study of the earth’s shape, orientation in space and gravity
5
Q
what’s the shape of the earth
A
ellipsoid
6
Q
what’s a geoid, what is used as its base, what affects it
A
model of the earth, uses sea levels as a base, gravity
7
Q
regions on earth with more mass have a stronger/weaker gravitational pull than regions with less mass
A
stronger
8
Q
what’s a datum, is it above or below the geoid
A
reference surface, or model of Earth, used for plotting locations
above or below depending where the datum is
9
Q
what’s a datum transformation
A
series of calculations that change from one datum to another
10
Q
whats WGS84 and NAD83
A
WGS84: developed by the US department of defence for GPS users worldwide
NAD83: designed for the US and Canada
11
Q
what is the bulging at the poles due to rotation
A
ellipsoid
12
Q
the ____ model uses differential gravity to define mean sea level
A
geoid
13
Q
_____ are mathematical reference surfaces used to fit the geoid as best as possible
A
datums
14
Q
datums are used to establish what?
A
geographic coordinate systems
15
Q
define geographic coordinate system
A
global reference system for determining a location on a 3d ellipsoid
16
Q
what are the imaginary lines on the globe that run from pole to pole
A
longitude
17
Q
what are the imaginary lines that increase moving east to west to 180 degrees
A
longitude
18
Q
____ is the longitude line at the origin of 0 degrees
A
prime meridian
19
Q
east of the prime meridian is +/- and west is +/-
A
east: +
west: -
20
Q
what are the imaginary lines on the globe that run from east to west to 90 degrees
A
latitude
21
Q
____ is the latitude line at the origin of 0 degrees
A
equator
22
Q
north of the equator is +/- and south is +/-
A
north: +
south: -
23
Q
which coordinates come first in GCS?
A
latitude, longitude
24
Q
on a cartesian plane, the x-axis is longitude/latitude and the y-axis is longitude/latitude
A
x: longitude
y: latitude
25
which directions are negative in decimal degrees
south and west
26
formula to convert DMS to DD
DD = D + (M/60) + (S/3600)
**remember S/W are neg.
27
why is measuring distance in a GCS problematic?
lines of longitude merge at the poles (latitude are equally spaced)
28
define map projection
the conversion of locations from a 3D earth to a 2D surface
29
projections results in distortion of what
size, shape, distance or direction
30
what are the 3 main developable surfaces
1. azimuthal (flat)
2. conical (cone)
3. cylindrical (cylinder)
31
the developable surface is typically orientated in which 3 ways
1. normal
2. transverse (pole to pole)
3. oblique
32
which projection does Canada stats use? is it secant or tangent?
Lambert Conformal Conic
secant (2 pts of contact)
33
what type of projection is the mercator map? what is it good for?
cylindrical, navigation
34
T/F: all models are wrong
true
35
T/F: projected maps are all wrong
true
36
what is the projected coordinate system? what is it based on
coordinated on a flat 2D surface with constant lengths, angles and areas. based on GCS -> based on an ellipsoid
37
what is the universal transverse mercator?
international metric coordinate system
38
UTM divides the earth into ___ zones that are ____ degrees of longitude
60 zones, 6 degrees
39
UTM is measured in what
metres
40
UTM x/y coordinates are called what? what do they count and from where?
x: easting -> counts E/W of the central meridian
y: northing -> counts N/S of the baseline (equator)
41
in the northern hemisphere, northings count from the _____?
equator
42
in the southern hemisphere, the equator has a value of ______? how do you calculate the distance from it?
10,000,000 -> false northing
distance from equator subtracted from the false northing
43
each UTM zone has a central meridian with a value of?
500,000 m
44
locations E/W of the central meridian are added/subtracted from the central meridian
E: added
W: subtracted
45
what's lethbridge's UTM coordinates
UTM12U
46
list pros/cons of UTM
pros: minimal distortion, uniform grid system, global coverage
cons: can't be used in polar regions, limited zone width
47
what's the dominion land survey?
western canada divided into 7 meridians
48
what's the base unit of measure in a dominion land survey? what are the measurements?
townships, 6 miles x 6 miles
49
_____ compensate for convergence in dominion land surveys
correction lines
50
townships/ranges start where and the numbers increase how?
townships: start at 1st North of the baseline, increase to N
range: starts with range 1 in each meridian and increases to W
51
what are the components of this? 7-13-17-8-W3
w3: west of the third meridian
8: range
17: township
13: section
7: legal subdivison
52
each township is divided in to __ sections, (each section is divided into ____ quarter sections), each section is divided into ____ legal subdivisions
36, four, 16
53
what's GPS
technology that broadcasts satellite signals for navigation and position determination on earth
54
what is the global navigation satellite system?
overall term for technology that uses satellite signals to find locations on earth
55
what are the 3 GPS segments
space, control, user
56
whats the ephemeris
part of the space segment of GPS: information about the satellite's status, orbit and precise location information
57
the space segment signals contain what? how is it sent?
satellite's position and the precise time of signal transmission, digital pseudo-random codes
58
what's the C/A code, P-code and Y-Code?
all part of the space segment
C/A code: coarse acquisition, information accessible by all GPS receivers
P-code: precise, accessible by military receivers
Y-code: encrypted version of P-code intended for military use
59
what's the control segment. what do they do?
series of worldwide ground stations that monitor signals from GPS satellites. corrections uploaded to satellites for orbits, time and atmospheric conditions
60
what's the user segment? what do the number of channels do? what's the difference between single and dual frequency?
GPS receivers on the ground that pickup satellite signals.
number of channels controls the number of satellites signals can be picked up from
single: L1 frequency
dual: L1 and L2 frequency
61
what's trilateration? 3D trilateration?
finding your position based on the distance from a minimum of three points
finding a position on the earth's surface (ellipsoid)
62
how does finding your position with GPS work? how many points are involved?
satellite transmits signal to receivers -> signal includes time of transmission and position of satellite
one point in space, one on earth and one position of GPS receiver ** receivers use a fourth satellite to account for time errors and provide a vertical location
63
define pseudo-range, how do you calculate it?
distance between a GPS satellite and GPS receiver
speed of light * transmission time
64
what are the 5 sources of GPS error and what are they/how are they accounted for?
time dilution of precision:
position dilution of precision: error introduced by position of satellite in the sky, good geometry
atmospheric interference: control centre accounts for this
multipath signals: reflection of GPS signals from surrounding surfaces, antennas
selective availability: degradation of the timing/location that was intentionally introduced
65
what's differential GPS? what are two examples?
method of ground-based corrections in addition to satellite signals, real time kinematic and post processed kinematic
66
what is wide area augmentation system?
network of ground stations that measure variation in GPS signal
67
what are the 3 principles of a design problem?
1. focus
2. simplicity
3. cross-disciplinary way
68
a ____ represents spatial data that provides a reader with information
map
69
maps can be ____ representations of the real world. what are some examples?
abstract, mapping ideas or concepts like boundaries or borders
70
maps are complex ____ of reality
complex
71
what is cartographic generalization, what controls generalization?
simplification of representing items on a map, scale
72
explain douglas-peucker simplification and displacement
douglas-peucker simplification (line): simplification of curves using subset of original lines
displacement: features moved to increase clarity, smoothing or enhancing
73
define geographic scale
real-world size or an area of a feature
74
define map scale, how can it be displayed, explain each
value representing the number of units on a map relative to the number of the same units on the ground
representative fraction: # of units on map : # of same units on ground, unitless (1:50,000)
verbal scale: uses relatable units (1 cm is equal to 500 m)
scale bar: geographic representation of the map scale
75
differentiate large and small scale maps
large: shows small region, 1:5,000
small: shows large region. 1:250,000
76
accuracy vs precision
accuracy: degree to which information matches true value -> amount of error
precision: measures exactness or repeatability -> # of sig. figs.
77
standard mapping accuracy is what rule?
0.5mm
78
what are reference vs thematic maps
reference: shows geographic features in relation to each other, ex: navigation
thematic: conveys information about a single topic
79
explain and give pros/cons for the different classification methods
natural breaks: based on natural grouping. pros: good for uneven distribution. cons: not good for comparing data sets & hard to determine proper number of classes
quantile: each class contains equal number of features. pros: understanding relative position. cons: similar features may end up in different classes or wide range of value may end up in same class
equal interval: divides range of values into equally sized subranges. pros: familiar values (temp, percentages). cons: clustering, bad with uneven distributions
80
what does normalization do?
creates a ratio map and allows for comparison between different areas
81
what nine elements must be included on a map?
title, data frame, scale, legend, descriptive text, north arrow, sources, name/date/class number, neatline
82
who is the grandfather of GIS, which book did he write, what did he contribute?
Ian McHarg, Design with Nature, sieve mapping
83
whos the father of GIS, what did he do?
Roger Tomlinson, created Canadian geographic system (first operational GIS)
84
what are the components of GIS?
geographical: any data with spatial coordinates, points, lines, polygons, rasters
information: databases and data integration. non-spatial data (ex: income data, age)
system: integration of data and tools, hardware, software, toolboxes, printers, users
85
what's metadata
data about the data
86
what's a geodatabase, feature class, feature dataset?
geodatabase: single folder that can hold numerous files with almost unlimited space
feature class: single data layer
feature dataset: grouping of multiple feature classes
87
what's discrete object view? examples?
representing the world with a series of separate objects. points, lines, polygons
88
what's continuous field view? examples?
viewing the world as items that vary across the earth's surface as constant fields. change in elevation, temperature, precipitation
89
whats raster data model? pros/cons?
model that uses an array of equally sized cells arranged in rows and columns, used for continuous data.
pros: one attribute per cell -> good for math/analysis, location is implied
cons: cell size can result in blocky images, poorly represents linear functions, generalization within a cell
90
pros and cons to vector data
pros: no generalization, nice to look at, can hold lots of attributes, accurate locations
cons: no good for continuous data, not possible with a polygon
91
what's an attibute?
non-spatial data associated with a spatial location
92
what's a join?
linking two or more attribute tables, common field required
93
what's a relate?
defines relationship between 2+ tables but does not attach it, common field required
94
what's a spatial join? different types?
used when there is no common field
join one-to-one: summarizes joining information with each feature in target layer
join one-to-many: output contains multiple copies of target feature if multiple features overlay it
95
queries use which language
structured query language
96
what are the different Boolean operators?
AND: intersection of a and b
OR: union, all of a and all of b
NOT: all of a, but not if it is also b, no b
XOR: all of a and all of b but not when they're both
97
the united states contains/completely contains Texas/Kansas
the united states contains Texas
the united states completely contains Kansas
98
alberta is within/completely within canada
within
99
what's digitizing?
process of creating points, lines, or polygons which represent features from a map or image
100
what's georeferencing? what data is needed?
process of aligning an unreferenced dataset to one that has a spatial reference system
unreferenced data, dataset with real-world coordinates, identifiable locations in both data-sets
101
what are control points. examples of good vs bad
locations that are identifiable and have known coordinates. good: corners of buildings, road intersections. bad: tops of buildings, trees
102
what number of ground control points are required for each transformation and what does it do?
zero-order shift: 1, shifts the map
first-order affine: 3, shift, scale, rotate
second-order: 6, bend image
third-order: 10, twist image
103
what is calculated when a transformation is applied, what is it?
residual error, difference between georeferenced point and specified location
104
what is the root mean squared error, how many GCPs needed?
square root of the mean value of all the squared residuals, four
105
what is forward residual, inverse residual and forward-inverse residual?
forward residual: error in same units as data frame
inverse residual: error in pixel units
forward-inverse residual: measure of overall accuracy measured by pixels
106
what is it called when an empty cell s given a new value based on its location during transformation? what are the 3 common methods? explain each
resampling
1. nearest neighbour: adopts value of nearest pixel, best for discrete data
bilinear interpolation: weighted averaged of 4 closest pixels, not suitable for discrete data, used for continuous
cubic convolution: weighted averaged of 16 closest pixels, not suitable for discrete data, used for continuous
107
define spatial analysis. what are different ways this works?
how features are spatially related to one another
constraints, proximity, networks, clustering
108
what's thiessen polygons?
spatial analysis, proximity
area closer to a central point than any other feature
109
what's a buffer, they use what to measure?
spatial analysis, proximity
built around a point, line, polygon
euclidean distance: straight line from centre
110
what's network analyst? measured by what?
measured manhattan distance, distance between two points on a grid
111
what is the vertical datum based off of?
used for measuring elevation, based on mean sea level and determined by shape of geoid
112
what is digital elevation model?
representation of the surface of the earth?
113
what is triangulated irregular network?
vector-based approach to creating digital elevation models
114
advantages of DEM vs TIN
DEM: accepts data directly from matrix of cells. less complex, faster processing
TIN: accepts randomly sampled data, displays linear features, can vary density of points according to terrain
115
disadvantages to DEM and TIN
DEM: must be resampled if irregular data is used, may miss complex topography, can include redundant data in low-relief areas
TIN: data intense and longer processing time, each vertex stores x,y,z coordinates
116
what's digital surface model?
measurements of ground elevation heights as well as the objects on the ground
117
where are suitable solar panel locations?
barren, grassland, herbs, south facing, not in coulees
118
what are predictive surfaces?
using measurements at a set of locations to predict values in locations that were not measured, continuous data
119
predictive surfaces can be used to interpolate, what does that mean? what's the difference between exact/approximate interpolation? what's the difference between local/global interpolation?
interpolate: process of predicting values between known points
exact: creates a surface that passes through all known points
approximate: creates a surface that may vary from known values
global: use all data in study area
local: use spatially defined data subsets
120
some predictive surfaces can be used to extrapolate, what does that mean?
extrapolate: predicting values outside of known sample points
121
potential predictive surfaces include:
inverse distance weighting, natural neighbour, spline, trend
122
what is inverse distance weighting, is it local/global/exact/approximate, benefits/limitations
values weighted based on distance, local, exact
123
what is natural neighbour, is it local/global/exact/approximate, benefits/limitations
values based on Theissen polygon overlap, local, exact
124
what is spline, is it local/global/exact/approximate, benefits/limitations
users can adjust weight parameter to smooth (regularized) or stiffen (tension) the surface, local, exact (regularized) and approximate (tension), exceeds min/max values
125
what is trend, is it local/global/exact/approximate
polynomial increases the complexity, global, approximate
126
**choosing the right surface slide**
127
Rank the following scales from large to small scale
A) 1:10,000
B) 1:250,000
C) 1:50,000
D) 1:100,000
a, c, d, b
128
Is the distance of one degree of longitude the same at the equator as it is at 60 degrees north?
No: the lines converge at the pole -> become shorter as you move N or S of the equator
129
