Lecture 1 Flashcards
1
Q
What is GPS
A
Global positioning systems
2
Q
What is geomatics
A
Geographical analysis using computers, tying data with a particular place
3
Q
What is the base before we split it into sections
A
Reality
4
Q
What data can we add to gis maps!
A
Data labels and values
5
Q
What is remote sensing?
A
Observing a particular feature from a distance
6
Q
What is an example of remote sensing
A
Satellite data
7
Q
Why is remote sensing seeing a rise in popularity
A
Drones and technology is becoming cheaper so starting to get rolled out on a larger scale
8
Q
Who can generate their own remote sensing data
A
Anyone
9
Q
What is the principle to gis
A
Network of orbiting stallites
10
Q
What is the issue with old aciol maps
A
All the information is in one place/document hard to distinguish the data
11
Q
What is the desire of change from gis
A
The desire to have more than one theme
12
Q
Who discovered the cause of a cholera outbreak in London using rudimentary GIS
A
Jon Snow
13
Q
What are the main GPS systems in use today?
A
NAVSTAR USA and Glonass Russia, also Galileo Europe
14
Q
How many satellites are run by nav star
A
24, each with 12 hour orbit
15
Q
How does a GPS find your location
A
Triagulates data from 3 points
16
Q
How manny satellites are needed to calculate altitude
A
4
17
Q
Is every GPS position 100% accurate
A
No
18
Q
What is the standard error range for GPS location
A
- 25m 95% of the time
19
Q
What measures the accuracy of a GPS fix
A
Dilution of precision
20
Q
What will some GPS systems do while you are collecting data
A
Give a constant DOP reading
21
Q
What causes delays through the atmosphere
A
Ionisation as it passes through the atmospheres, some have a built in counter delay but this may not be accurate
22
Q
What is signal multi path?
A
Multiple signals from the state lites which is bouncing of buildings,
No way of accounting for this apart from making sure you can see as many satellites as possible and move into an open space
23
Q
What is a receiver clock error?
A
Clocks on phones may be out compared with the atomic clock, meaning any time differences would screw up data
24
Q
What are orbital errors
A
Satellite orbit can get out of sync so data might be screwed
25
Why might people manually turn down or distort satellite signal,
Selective availability, US used it to stop enemies using their satellites or finding out about military bases ect, terminated in 2000 which improved civilian reception
26
How can we improve gps accuracy?
Use systems such as differential GPS, uses 2 receivers rather than just one
27
How does differential GPS work
Error and position should be accurate for both receivers, if they are not you subtract the error for our fixed base station from GPS receiver
28
What is vector data
The simplest forms of data, points lines polygons and surfaces
29
What is topology
How different data fit together and overlap
30
What does GIS use
Spatial data
31
What is the most basic form of spatial data?
The point, position lat long ect
32
What separates out data in gis
IDs
33
What is data in a single table in gis called
A flat file
34
What is the negative with a flat file
Very useful but very simple
35
What can points be turned into
Lines or shapes
36
How does heywood describe topology?
How spatial data is related to each other based on what it’s next to what is within bits of data
37
What are the 3 layers to. Topology
Adjacency, containment and connectivity
38
What is the goal in showing topology data?
Most amount of information with limited amount of data
39
Why else can we show in data points
Size of the data points could show size of the city or place
40
In line data what is each circle or point called?
A node, the line is the link
41
What is the valency of the node
The number of points at the node, a crisis road would be 4 valent
42
What are the 2 different types of data associated with polyline
Link data, one way streets, number of motorway lanes l, attaching data to individual points,
Node data, where roads meet eg roundabout crossroad
43
What are polyline networks
Say what is flowing into what, requires good attribute data, data about road networks, Behind satellite data on gps
44
What is polygon data
Lines connected together to make a shape
45
Why can polygon data be used for?
Representing postcodes countries
46
What are the types of construction of polygon data
Island eg woods, adjacent eg countries and nested eg contour lines
47
What can be shown as an individual surface
Elevation, rainfall, temperature, population ect
48
What are the main advantages of vector data
Data is compact, effecient, well suited for map output, resolution can be independent of detail
49
What are the problems with vector data
When would you use a specific point/polygon, what one user requires will be different to the other
50
What is raster data
A grid of numbers, can show different sorts of data, especially spatially continuous
51
What do analysis on rasters create
Secondary products or derivatives
52
What is each imagine made up of
A series of numbers
53
What determines raster quality
Resolution
54
Where is raster data normally displayed
Behind other data normally to an extent transparent
55
What is the negative with raster data
Can skew specific points
56
What happens when we convert from raster and vector vice versa
Start to loose information
57
What is raster good at showing
High spatial variability l, simple data structure, overlay options are straight forward
58
What are dtms
Digital terrain models
59
What is the main place where dtms come from
Satellites
60
Why derivatives can we make from dtm
Steepness of slope, which way it’s facing
61
What can we get if we draw a line over height raster data?
Graph of altitude
62
What is TIN
Triangular irregular network, good for visualisation
63
When were data based developed
1950’s and 60 by ibm in response to the amount if data that is needed to be stored
64
What is a database?
A collection of data usually stored as single or multiple files
65
What is a DBMS
Database management system, a set of computer programs for organising information at the core of which is a database
66
What does the database allow us to do
Access files from and small space while having lots of storage space
67
What is at the heart of any gis program
DBMS
68
What is the main advantage of a database
The data that we are storing is physically separate to what we are doing with it
69
By changing the information on screen what are we not doing to the underlying database
Changing it, remains static, altering the way that we are viewing the database
70
What is the user advantage of a database
The user does not need to know how the data is stored
71
By altering the underlying data base what does this do to the overall map
Changes it for us
72
What is the cost advantage with databases
Reduced software development costs
73
Is the database secure
Yes
74
Can the data base be views singularly or multiple times
Multiple
75
What are the main advantages of databases?
Reduced data redundancy, enables maintenance in data quality and integrity,
Data self documented, consistent
76
What is data redundancy
How the data is used, in data bases we can use data that can be used in multiple projects
77
What is attribute data
Geographic information such as spatial location at that point
78
What sort of attribute data can be associated with roads
Classification, width, flow
79
What sort of attribute data can be associated with soils
Colour, texture organic matter ect
80
What sort of attribute data can be associated with weather
Temperature, precipitation, wind ect
81
What sort of attribute data can be associated with rivers
Discharge,
| Velocity, width ect
82
What is attribute data also referred as
Aspatial data, constraints with the geographic coordinates
83
What do we need to do with aspatial and spatial coordinates
Combine them within a database
84
What is floating point data
Decimals
85
What are integers
Nominal ordinal or interval
86
What is a domain
Set to controls the range, eg temperature -50 to +50 degrees
87
What is another name for records
Tuples
88
Why are non data components
Operations, user function- Data language, used to describe data base contents-query language Standard language used to edit
89
What is the most simple data model?
A flat file
90
What are the negatives to a flat file
Very simplistic cannot deal with relationships between objects
91
What happens if two sets of data a stored seperatly in a shape file
Cannot tell us how they interlinked
92
What is a relational data model
Use the IPs to create linkages between the data files
93
Why do data based sometimes cause issues
Not designed for GIS
94
With gis data what happens with the files
All linked together which makes the gis data
95
What is a shp file
Tells us of the geometry of the file
96
How many files do shapfiles have at least
3
97
What is a DBF file
Attribute data
98
What is a sbx file
Index of the feature of geography
99
What are GRID files
Raster data
100
What is a grid file made up of
Aux file and adf file
101
What is arccatalog
Seperate software to arcmap, took for exploring and managing data
102
What does arc catalog look at?
Not individual pieces of data but groups of files
103
What is meta data?
Data which tells us about the data itself
104
Give an example of the way that a library would use meta data?
Authors, Titles, ISBN numbers. Subject
105
Who attempted to standardise meta data?
Federal geographic saga committee,
| But deemed too complicated
106
What standards are now used for meta data
Light meta data,
107
What is the description of light meta data
Title, keywords, abstract purpose
108
What is spatial data within meta data
Bounding coordinates
109
What examples of attribute meta data is there
What other data in the database
110
Where do most of our data sources come from
The internet, vector data, digital models, satellite imigary
111
How could you collect your own data?
Ground surveys
112
What are some steps between data capture and gis data base
Editing, re projection, generalisation, edge matching, layering
113
What often shapes a GIS project
The data available
114
What is the name given to the place where data is stored on the internet
Geo libraries
115
What does data sometimes come in
A raw format, conversion into esri, processing within arccatelog
116
What are governments currently doing with data?
Trying to make it more accessible
117
What is arc gis online
Ads base maps and other things within gis, individual pieces of raster data, hosted by ESRI
118
What compromise might we make in free online data
Lower resolution data, data only part processed
119
What data that can be obtained online can show the whole world
Raw satellite data
120
What is the advantage of satellite data
Can show remote places not often looked at
121
Where does most free satellite data come from
USGS/NASA or Glovis
122
What is the first processing you will need to do with satellite data
Unzip uncompressed it
123
What will you have to do to satellite data
Reproject it
124
What are the key features of digimap
Higher resolution maps are available, some data is vector so can be manipulated online
125
Give an example of vector data
Strategi, meridian, vectormap, mastermap
126
What resolution are landranger maps
1:50000
127
What is NTF
Neutral transfer format, more of a raw format
128
How do we use NTF
Need to convert it
129
What does DTM come in
ASCII
130
What is Photogrammetry?
Used aerial photographs, method of remote sensing , dates back to ww2 use
131
What is photogrammetry good for
Assessing changes over time, can create 3s images,
| Wide area views, high spatial resolution
132
What is the negatives with photogrammetry
Difficult to find online,
| No spatial referencing, scale varies across the image
133
How would you fix photogrammetry in terms of spatial referencing
Would need some geo referencing
134
In terms of the plane, what impact does altitude have
Different heights effects scales of the image
135
What is it called where we create 3D images from Ariel 2d photos
Stereo imaging
136
What has enabled the increase of stereo imaging
Increased availability of drones ect
137
What are the features of digitising other peoples maps
Quite easy but time consuming
138
What are the two main processes to digitisation of maps
Manual and automatic
139
What are the two modes of manual digitisers
Point mode, lines are generalised as a series of points from the user, stream mode, liners are generalised using a series of points set at time intervals
140
What are sources of error
| In manual digitising
Shaky hands, elements wrongly perceived, line thickness, generalisation
141
What do we use in automatic digitisation
A scanner
142
What are the sources of error for automatic data
Same as manual plus, optical distortion, scanning unwanted info, still slow, could be poor resolution
143
What is remote sensing
Capturing data remotely, eg satellites
144
What is the main type of remote sensing
Satellite remote sensing
145
How does satellite remote sensing work
Radiation is dense by satellite that is emitted from the surface
146
What bodies emit radiation
Anything that is warmer than -273 Celsius
147
What does most remote sensing focus on
Electromagnetic radiation
148
Why might we want to use different wave lengths and sensors
Because they can detect and show us a different image
149
If some thing is blue what is happening
Blue light is reflected all other colours are absorbed
150
Why is looking beyond the visible range useful
Doing detection of what is going on at he earths surface
151
How can electromagnetic sensing help for identifying objects
Thing in pictures that look the same can be differentiated using EM
152
What do all satellites have on board
A range of sensors
153
What can certain satellites do with detecting gravity
Look at changes in ground water (grace)
154
What are the most commonly used satellites
Polar orbiting- Landsat, AVHRR, MODIS, Geostationary- Meteosat and GOES
155
What satellite uses vegetation in the visible and inferred spectrum
MODIS
156
If statellites do not take images what do they do
They build up raster data via a swath width
157
What varies between satellites
Resolution size
158
Which satellite uses a much smaller pixel size
SPOT
159
What size pixels do lansat use
30meters
160
What is the typical Rasta range for an 8 bit system
0-255
161
How many TM bands does the new Landsat have
13
162
What can penetrate cloud cover with satellites
Infra red
163
How can we use stallities to create more detailed images
Combining satellite bands
164
Why can Landsat sometimes be bad for GIS
Can’t distinguish between some land features
165
How are DTMs created
Remote sensing techniques
166
What do DTMs create o
Very high resolution data sets
167
How do DTMs collect data?
Space craft or upper orbit aircraft, side looking camera sends pulses which bounces back
168
What are the advantages to remote sensing
Unlimited rescources with good spatial resolution, observations are unbiased
169
What are the disadvantages to remote sensing
Expensive, does not produce measurements,
170
Why is there loads of room for error in remote sensing
Complexity
171
What are the two types of error with remote sensing
Radio metric and geometric
172
What are radio metric errors
Anything that stops data reaching sensors, cloud and haze, could be problems with the sensor, could be problem with processed that calculates the image,
173
What are atmospheric corrections
Making corrections for cloud and haze ect
174
What eve lengths are less effected in haze
Long
175
What are random sensor errors
Bit errors
176
What are systematic radiometroc errors
Eg software malfunctions like corrector error Landsat
177
Why was the Landsat systematic error
Lines needed to be pushed back into line, skew correction
178
What are geometric errors
The problem with the shape of the earth is the problem
179
What does geometric errors occur
Different heights of recording can create image distortion
180
What do edges of remote sensing maps need to go though
Edge matching to create a transitions between the two
181
Why is it easier to change raster data that has become distorted
Easier to squeeze and push the image around
182
What is it harder to warp vector data
Hard to chew it while remaining solid topology
183
What is georegistation
Series of control points, pick out points in image and slide it over with control points,
Adjusting a map to the geographic location of a known good map
184
What is the negative with using landscapes for georegistration
The landscape can change over time eg rivers
185
What are good control points
Trains tracks, City land marks, things that are fixed through time
186
What is rubber sheeting
Adjust features in a non uniform manner
187
How do we make a rubber sheeting more accurate
More ground control points,
| Need to be spread out as well
188
As a rule of thumb how should elements be digitised
In order of complexity m, points lines then polygons
189
What do we need to do for manual editing
Generalise each element into a series of points, that line represents that street so you can then add attribute data such as the street
190
What is automatic vectorisation
System finds lines automatically, digitises automatically
191
What is quality
Factor used in GIS metadata,
| 9 key parameters
192
What is accuracy
The ability to get the correct answer, when estimates value approaches it’s true value
193
What is precision.
How repeatable it is to get the correct answer, or defined, eg lots of decimal spaces
194
What is bias in data quality
Is there systematic variation of data
195
What is resolution in data quality
Resolution of raster data sheets
196
What is completeness of data quality
Means the data set is complete both temporally and spatially
197
What is data combatability
Consistent data scale and coordinate system
198
What is data consistency
Did different people collect the same data or is it different, had biased been reduced
199
What is applicability
Can the data set be used to solve the problem
200
What is the process called where we remove errors
Data cleaning
201
Which errors are easy to spot
Attribute data, spatial errors are harder to spot
202
What are common spatial data errors
Missing entities, eg roads. Duplicate entries, mis locates entities, noise irrelevant data
203
What are artifacts of digitisation
Undershoots or over shoots, wrongly placed nodes, loops
204
What is a conceptual error
How we perceived what is being mapped
205
What are source data errors
Maybe the original cartographer made and error and maybe we are just copying that
206
What can happen by mismtake in data cleaning
Intentional gaps can be destroyed creating more errors
207
What is the basic problem with converting the earth to maps
The world needs to be treated as a flat surface
208
What is the most common projection for theUK
Mercator
209
In a normal cyclindrical projection what becomes distorted
The poles become bigger and equator is smaller
210
What is the main example of distortion on Mercator
Greenland vs Africa, look the same size but africa is 14x bigger
211
Why was the Mercator often used
Made Europe and the uk look bigger
212
What is azimuthal map projection
Put onto a circle, shape preserved in the middle well but not on the outsides
213
What does azimuthal preserve
Distance
214
Give an example of a map that preserves area
Werner projection
215
What is conic projection
Displayed on a cone, scale is preserved but area and distance is distorted
216
What map projection do sattelites use
Sinusoidal, preserves area storage shape
217
What are the two main methods of spatial referencing
Geographic coordinate systems and rectangular coordinate systems
218
What is the idea with rectangular coordinates
Map is made by projecting lines of lag and Long onto a flat surface, errors are smaller on smaller scale maps
219
What is a graticule
Grid
220
What is the projection that the British national grid is based on
Transverse Mercator
221
How many grids in the British national grid
700x1300,
| First divided into 100 squares
222
How can lidar determine trees
Not all of the lidar rays will go through, sattelite then knows these are trees
223
What is a surface o
A continuous variation is space of a 3rd dimensional terrain
224
How can we display 3D surfaces in gis
Wire diagram which shows a developed terrain
225
What can be draped over a wire grid on gis
An image
226
What is surface analysis
Creating a new output from one or more input rasters
227
What is constraint stretching
Increase or change the range fan raster image, enables more detail to be seen
228
What is reclassification
Change cell value to isololate particular bands so we can see certain aspects more clearly
229
What are neibourhood functions
Look at what’s close in raster and use it to influence data around it, can filter and smooth the data
230
What are the two data types in neibourhood functions
Proximity and filtering
231
Why is it hard to calculate distance across rasters
Depending on the pixel size and if you draw a line through the raster
232
Why is neibourhood function useful
Can be used to filter data to make it more manageable, filer can be in size shape or function
233
What are applications for neibourhood data
Smoothing of noisy data, image sharpening edge detection
234
What are some DEm derivatives
Slope, aspect, hillshade
235
What si aspect
Direction thy a slope faces
236
What is a kernel
5 cells
237
What are view sheds
Show what can be seen from distance, used for planning wind turbines
238
What makes multiple raster analysis easier
Using from the same data, eg Landsat
239
How can u make a composite imagine using bands
Combine 3 blue red green to make full colour
240
What is surface draping
Name given when a surface is overlain by another Layer, eg satellite imagery, adds mid geographic detail, geology cities forests
241
What are the 2 methods of satellite land classification
Unsupervised and supervised
242
What is unsupervised classification
Compute does the work, you decide how many clusters, computer picks up and divids clusters
243
What is supervised classification
Need to train the pc, use field work to identity pixels to teach the computer
244
What is mapematics
Intergrating rasters together to create more detailed maps
245
What is the most simple analysis with vector data
Measurement,
| Uses phythagorus
246
What is a querie
Can query aspatial data, ask questions about the attribute data, eg how many universities are in the West Midlands. Or add a scale within 50km
247
What is buffering
Drawing a box around the area of interest to see what’s in that zone,
