Spatial Data Flashcards
(88 cards)
1
Q
What are some methods to generalize Maps?
A
- Selection (Omit Unimportant)
- Combination (Merge Adjacent Features)
- Simplification (Reduce detail, maintain shape)
- Displacement (Locational Shift)
- Exaggeration/Enhancement (Symbology)
- Smoothing (Digital Maps)
2
Q
What are 3 Ways to express Map Scales?
A
- Representative Fraction (Small scale vs. Large Scale)
- Word Statement
- Scale Bar
3
Q
What are the 3 units of Measuring?
A
- Metric (mm, cm, m, km)
- Imperial (in, ft, yd, mi)
- Conversions (2.54 cm = 1 in.. 63, 360 in in 1 mile)
4
Q
Express following as representative Fractions (1:xx, xxx)
- 1 cm = 250 m
- 1” = 240’
- 1” = 1/4 mi
A
- 1/250,000
- 1/2,880
- 1/15,840
5
Q
The distance between 2 features on a photo is 10.50 cm and the corresponding distance is 5 km on the ground.
Calculate approx. scale of photo?
A
10.5 cm/5 km –> 10.5 cm/500,000 cm = 1/? –>
=1/47,619
6
Q
The distance between two road intersections measures 13.55 cm on a 1” = 1/2 mile air photo.
Calculate the ground distance (in m)?
A
1 mile = 63,360 in –> 1/2 mile = 31,680 in –> 1/31680 = 13.55 cm/? cm –>
? = 429,264 cm = 4,292.6 m
7
Q
Calculate the length (in cm) of 2 miles on a 1:250,000 map
A
2 mi = 2 x 63,360 in = 126,720 in (There are 2.54 cm in an inch) 126,720 in x 2.54 cm/in = 321,868.8 cm 1/250,000 = ?/321,868.8 cm ? = 1.3 cm
8
Q
Give 3 ways to Determine Area of Polygons?
Explain 2 examples of one
A
- (a)Planimeter, (b)Break into regular shapes, (c) Squares;
- Square measure (Boxes)(Count how many boxes include more than 50% of the desired area inside the box)
- Dot Grid (Hold the Dot Grid over the desired area and count how many full dots are within the area
9
Q
Explain steps in determining the area of a polygon using the Square technique
A
(1. ) Determine the length of the edge (side) of square
(2. ) Then convert to Real World
(3. ) Calculate ‘ground area’ of one square; Length X Width
(4. ) Count the squares/dots within the polygon
(5. ) Multiply answer by ground area of each square to determine area of polygon
10
Q
Explain Steps in determining the area of a polygon using the Strips Technique
A
(1. ) Determine the with of line spacing
(2. ) Measure the Lengths of all the strips and sum
(3. ) Convert to ‘Real world’ (Ground) distance
(4. ) Determine Area; Area = L*W
11
Q
What is GeoReferencing?
A
A Geographic reference,
-Provides a unique description for locations of earth’s surface
12
Q
What is Non-metric?
Examples…
A
*Non-Measured (Without Measure) Examples; -Placename (London, Ontario) -Landmark (Eifel Tower) -Street Address (900 Fifth St. Nanaimo, B.C) -Postal Code (V9R 5K5) -Phone Exchange (250, 604) -Census Tract -Political Riding -Cadastre
13
Q
What are some issues when using Non-metric for GeoReferencing?
A
- May be only known by “locals”
- at Global Scale - you may have repeats (Ontario, Paris)
- Often adequate for cultural features
- Anomalies - street addresses in Japan are chronological not ‘linear’
14
Q
What is Metric (Geo-Referencing)
-Examples…
A
- Our World (Measured)
- Linear offset (124m North of Oak and Main)
- Latitude/Longitude
- UTM Eastings and Northings
- Others (Public land survey system)
- Point based (Producing Coordinates)
15
Q
What are some advantages of using Metric for GeoReferencing?
A
- Infinite Resolution
- Good for all Parts of Globe
- No Ambiguity (Only 1 location possible)
16
Q
What is an Ellipsoid?
A
A centrifugal Force
-Ellipsoid affects and changes Longitudes
17
Q
What is an Geoid?
A
The true shape of the Earth
-Where there is a variation in gravity (density) and where gravity has force
18
Q
What is an Datum?
A
A reference surface used to determine location (coordinates)
*( A surface for generating longitude ad latitude coordinates)
19
Q
How many Datums are in your life now?
A
4 in Total;
NAD 27 and NAD 83 which we use now for Lat and Longs
20
Q
Describe NAD 27
A
*Surface to Surface
Clark 1866, Meades Ranch - Kansas
21
Q
Describe NAD 83
A
- GRS 80
- Center of Ellipsoid to Center of Earth
22
Q
Give several Examples of Graphs (Types)
A
*Pie, Scatter Plot, Line, Bar, 3D Box
23
Q
Define Terrian
A
“Shape of the Ground”
24
Q
What is Bathymetry?
A
Terrain under Water
25
Define Vertical Datum
Reference surface for Elevations
26
What does MSL refer to? (Geoid)
Mean Sea Level
27
What are some Methods for Depicting Terrain?
* Hachures (Old - Short lines to show mountainous)
* Hill Profiles (Really O - Middle Earth Style)
* Layer Tinting (Colour Bands represent elev. ranges)
* Hill Shading (Shadows to depict relief)
* Hill Shad + Layer Tint
* Spot Heights (Points labelled w/ elev.)
* Contour Lines (Lines depict same elevation - closer lines = steeper ground)
28
What does it mean if the contour lines are (slightly closer) bending upwards (almost like a point)
It is a Steep Gully or draw
29
What is an INDEX Line? (On a map)
The Dark lines that tell you the elevation
30
What does it mean if the contour lines are pointing slightly downwards?
It is a Ridge
31
What is a Map Profile?
A Cross Section of the Area.
32
How do you draw a cross section of a map correctly?
* Use edge of paper to transfer
- Mark start and end points on map ( A & B )
- Align paper along A->B & make a tic mark where contours cross paper
- Label index contours & as many intermediates as necessary & mark any special features (hill tops, creeks, rds, etc.)
- Use lined or graph paper, label Y axis with elevations and X axis with start and end points.
- Use tics to transfer elevations and any special features to profile
33
How do you determine total slope ratio or %?
Ex.
Contour interval = 20 m
line(420 m) crosses 4 contour lines (80 m elevation)
Rise/Run = Elev. Change/Horizontal Distance = "ratio" or %
Slope = 80 m / 420 m = 0.19 or 19%
Slope in Degrees = arctan (0.19) = 11 Degrees
34
Given 2 UTM coordinates discover Distance and Bearing between 2 coordinates
- >Draw & Label a diagram box with coord.
* Vertical Lines = Eastings
* Horizontal Lines = Northings
- Use SOH-CAO-TOA
- > Distance = Pythagorus theorum - a2+b2=c2
* a=diff. in eastings, b= diff. in northings, c= straightline distance
- > Bearing - Calculate using Tan or Arctan - rise/run=opp/adj. Add/Subtract from Cardinal bearing
35
You are given dot on grid inbetween northings: 5,490,000m & 5,489,000m (.8cm to dot, full dist.=2.0 cm)
Determine its exact location and the distance in Real World
Short Measure/Full Grid Measure = ?m/1000 m
UTM Proportion; 0.8/2.0=40%
Final Answer = 5,489,400 m N
36
You are given dot on grid inbetween Lat/Long: 0 sec & 60 sec or 1 min (1.1 cm to dot, full dist.=4.4 cm)
Determine its exact location and the distance in Real World
Measure Distance/Full Distance = ? sec /60 sec
UTM Proportion; 1.1 cm/4.4 cm = 25&
Final Answer = 15 seconds or .25 min
37
What is Triangulation?
A,K,A "Resection"
- Determine location using 3 bearings. Find features visible on map (photo) and real world (Ex. Mtn. Peaks)
- Determine bearings to features but plot "REVERSE BEARINGS" on the map.
- Plotted triangle provides indication of uncertainty (error)
38
How does GPS Work?
Consists of constellation of at least 24 satellites
-Your device connects to as many satellites that are available to determine location (We need 4 sat.s to get a 3 dimensional fix
39
What are some sources of error in GPS?
- Clock Error
- Ephemeris (Wobble)
- Receiver
- Ionosphere and Troposphere
- Multiple-Path Error (Ex. Topography, Trees, etc.)
- Position Dilution of Precision (position of satellite can affect precision of answer)
40
What is a Pseudo Random code?
Radio signals emanate from the satellites (travel very fast!)
41
How many atomic clocks do satellites have? And who cares for the monitoring of the clocks and satellites?
4
| The Military
42
What is Remote Sensing? (Regarding Air Photos)
Acquiring info about objects using EMR (sun's energy) without coming into contact
43
What is EMR and what kind of spectrum does it have?
"energy" that travels in form of a wave (emitted by stars)
Broad Spectrum:
-Gamma Rays (short), X Rays, UV, Visible Spectrum, Infrared, Microwaves, and Radio (Long)
44
What is an Atmospheric Window?
Portion of EMR that passes through atmosphere to the gorund
45
What are interactions of EMR with matter?
Reflection , Transmission(passes right through -ie.glass), Absorption, Refraction(the energy bends -ex. fish in the water looks displaced
46
What are 3 uses of Air Photos?
- Photogrammetry - obtain reliable measures and make maps.
- Photo Interpretation - ID Objects and determine their significance
- Orienteering - use to navigate
47
What are the different types of air photos?
- Oblique - At an angle, how we see. There are 2 kinds: Low (Don't see the Sky) & High (See the Sky as well as the Ground)
- Vertical - (
48
What is Stereoscopy?
-Use of binocular vision, over lapping pair of air photos, for a 3D image in brains.
-Stereoscopes: Lens; Cheap, portable.
Mirror; No Overlap, Entire stereo area view able - more room, No Lens Distortion
49
What is the flight line endlap/sidelap for an action shot?
- 60% - Endlap (for stereo)
| - 20-30% Sidelap (Ensures no missed area)
50
What could be some possible problems with endlap/sidelap action shots?
Drift, Crab or tilt (turbulance or banking)
51
What is the calculations (ratio) for Air Photo Geometry scale conversions?
```
PD/GD = Map Dist/Real World Dist
f/H = focal length/height of camera above ground (Focal Length / Flying Height
```
52
What is f and H?
| In Relation to Air Photo Geometry & Scale
```
f = Distance from lens to negative, greater the f the larger the scale.
H = Distance from lens to above the ground - flying height above the ground. Greater the distance (height) the smaller the scale
```
53
How do you determine flying altitude?
H (Height) + Elevation = Flying Altitude
54
What does 1 ft = cm?
1 ft = 30.48cm
55
What does 1 m = ft?
1 m = 3.28ft
56
What is a PP? (On each photo)
PP = Principle Point
57
What do the letters mean in this ratio?
| h/H = d/r
```
h = The Object Height
H = Flying Height Above Ground
d = object top to bottom length on the photo (displacement)
r = distance from NADIR to the top of object
(Nadir = the Photo's PP if Vertical)
```
58
What could increase displacement?
- Height of the object
| - Distance from the nadir
59
What is the equation used for discovering the height of an object? - Using Solar Angle (ã) & Shadow Length (L)
h = L x tan (ã)
60
What is the solar angle from?
Latitude, Date, and Time of Day
| LDT
61
What is CPP?
CPP = Conjugate Principle Points
| CPP gives you the following photos PP
62
What are the 7 factors used for aerial photo interpretation?
Triple S, TTPA
| Size, Shape, Shadow, Tone or Colour, Texture, Patter and Location - Association & convergence of evidence
63
What is the Fiducial Marks on a air photo?
They allow you to find the center of the photo, the PP/Nadir
64
Describe the factor Absolute that is used for photo interpretation?
```
Absolute = Surface Area of Object
Relative = Size of an unknown in relation to a known object
```
65
Describe the factor Size that is used for photo interpretation?
An Objects Surface Area, Form of an object, Cultural features,
They are RELATIVE Measures
66
Describe the factor Shape that is used for photo interpretation?
Natural features - tree species & Landforms
| Recognizable Shapes
67
Describe the factor Tone/Colour that is used for photo interpretation?
Sand has a bright tone
Water usually has a dark tone
(Moisture areas will show up darker than drier areas)
68
Describe the factor Texture that is used for photo interpretation?
The physical characteristics of an object will change the way they appear.
- Smooth - Pasture, bare fields, water, etc.
- Coarse - Forests
69
Describe the factor Pattern that is used for photo interpretation?
The spatial arrangement of objects.
(Different patterns of colour or texture and combination of the two.)
Repeating patterns indicate cultural features, random = natural.
70
What can Patterns help you determine (In Photo Interpretation)
Drainage Patterns can help determine bedrock types
71
Describe the factor Shadow that is used for photo interpretation?
Shadows cast by some features can air in their identification. ex. powerline poles
-Provides objects height, shape and orientation
72
Describe the factor Location/Association/Site that is used for photo interpretation?
Relating an object to its environment can help identify objects, ex; boats/ships at a dock
73
How do the 7 factors for photo interpretation apply to Forestry?
(W-FAT)
- Forest Cover maps, age, height, species, and stocking
- Appraisal of damage due to fire, insects, and disease
- Timber Volume Estimates
- Wildlife habitat management
74
What percent do the air photos over lap?
~30%
75
How can using Photo interpretation through applications such as soils help?
Once bedrock geology & surface geology are known, a soil scientist can classify soil types based on soil tone, slope, etc.
76
How can using Photo interpretation through applications such as Geology - Geologic mapping help?
The maps will show different drainage patterns can reveal what type of geology is present
77
What is the exact time for a satellite signal to reach Earth?
~0.06 seconds
78
What does GNSS mean?
Global Navigation Satellite Systems
79
Who uses NAVSTAR GPS and GLONASS?
NAVSTAR - USA
GLONASS - Russia
The only fully operational GNSS
80
What does LiDAR stand for? And what is it?
Light Detection and Ranging
An optical remote-sensing technology (via Active Remote Sensing using its own energy source) that measure scattered light to find range and other information on a distant target.
*It precisely measures the elapsed time for a reflection to return from the surface below.
81
How many ways are their to deploy LiDAR?
3 ways;
- Ground
- Airborne (Fixed wing, Rotary wing, UAV)
- Space (Satellite)
82
SRS - Define & Describe 2 kinds of orbit with space-borne platform
Satellite Remote Sensing
- Geosynchronous Orbit - it is put into an orbit around the Earth, so that satellite stays in the exact place throughout Earth's rotation
- Polar Orbiting - Orbits North to South, has approximately 90% coverage of Earth. And is in sync with the sun so it has the best picture of Earth
83
Regarding Image Scale Properties,
What is a "swath" photo
What is Spatial Resolution?
Swath = Width
Spatial Resolution is collecting pixel information - not continuous. It helps you determine what kind of scale you are going to use.
84
Q. Each pixel has ______ with ranges of;
```
A. Each pixel has a Brightness from 0 (=Black) to 255 (=White)
Black brightness (0) has low reflectance while White brightness (255) has high reflectance
```
85
What is the difference with; wavelengths, and frequency.
Wavelengths; The LENGTH of the waves
| Frequency; How FAST the waves get there
86
Give an example of shortwave and longwave (EM Radiation)
(Electromagnetic Radiation)
Short: Sun
Long: Earth (Non-reflective, infra-red. The heat that;s being generated back 0 thermal heat the earth is giving off.
Longer Wave: Manufactured - microwave
87
Give the 3 energy interactions that can occur with targets
- Absorption
- Transmission
- Reflection
88
Display Channels;
| Computer screen displays are based on tri-colour combination, what are the 3 colours?
Red, Blue, Green
