Mapwork Flashcards
List 4 Characteristics of a Orthophoto map
1:10000
Black & white aerial photo
More detail
Contour interval 5m
What is a map?
A reduced version of reality
What are grid references?
Points of intersection between lines of latitude and longitude
What is scale?
How many times reality has been reduced
What map features does this Mapcode represent:
2930CB
29 degrees longitude(N or S)
30 degrees Latitude(E or W)
Big block C
Small block B
How do you work out distance?
100 000
What is the formula for area and what are the steps to work it out?
Formula -> A = L x B
Steps:
- Convert measurements to Km
- Input values into the formula
List 4 characteristics of a topographical map
1:50000
Colour
Physical features
Contour interval 20m
List 3 ways scale is shown on a map
- Ratio scale
- Linear scale
- Word scale
How do you work out gradient?
G = H
—–
D
Gradient = Difference in height/Distance between the points
Steps:
- Work out D, measure and convert distance to Kilometers
- Convert the kilometers into meters by multiplying by 1000
- Work out H by working out the difference in heights between the 2 points.
- Then fill in the equation and divide both the H & D by the H, to get a 1:something ratio
How do you work out true bearing?
Steps:
- Draw a North to South line, making sure the object is in the centre
- Then draw a line from the inject to the other object
- Measure the angle with a protractor
How do you work out Magnetic bearing?
MB = True bearing + Magnetic declination
Steps:
First workout True bearing
- Draw a North to South line, making sure the object is in the centre
- Then draw a line from the inject to the other object
- Measure the angle with a protractor
Then add the MD, remember that it cannot be more than 360 degrees(Start from 0 again)
What is Altitude?
The height above sea level
List 4 ways altitude is shown
- Contour lines
- Spot heights
- Trig beacons
- Benchmarks(roads only)
What do contour lines far apart represent?
A gentle slope
What do contour lines close together represent?
A steep slope
What do contour lines that touch represent?
A cliff
What do almost circular contour lines represent?
A hill
List characteristics of a Ridge/Spur’s contour lines
- Higher altitude contours on inside
- “V” shaped
- Contours always point downstream
- River flows in direction to contours
List characteristics of a Valley’s contour lines
- Higher altitude contours on inside
- “V” shaped
- Contours always point downstream
- River flows in direction to contours
List characteristics of a Concave slope’s contour lines
Close together then far apart
List characteristics of a Convex slope’s contour lines
Far apart then close together
List 4 types of aerial photographs
- Horizontal(Parallel to ground)
- High oblique(angle 60 degrees from vertical- horizon visible)
- Low oblique(angle 30 degrees from vertical- no horizon)
- Vertical(Straight above)
List 2 advantages that both horizontal and oblique aerial photos have
- Show depth
2. Can recognize objects
List 3 disadvantages that both horizontal and oblique aerial photos have
- Size is distorted
- Objects near camera obstruct the view of objects behind
- Objects near camera appear bigger than objects behind
List 2 Advantages and 1 disadvantage of a Vertical aerial photo
Advantages: 1. Scale is the same, good for working out area 2. No objects obstructed by others Disadvantage: 1. Objects hard to recognize
What is a cross section?
A side view of a relief feature
What is GIS?
A system for manipulating, analyzing, capturing, checking, storing and displaying data which are spatially referenced to the earth
What does GIS stand for?
Geographic Information System
What does GIS do?
It links different layers to make a digital map
How do humans collect data for GIS?
Remote sensing - collects data of the earth’s surface through orbiting satellites and aircraft
What 3 types of data does GIS have?
Point - no length or area(Spot heights)
Line- Length but no area(Roads)
-NODES ARE THE START AND END POINTS
Area- Length and Area, polygon(️Farm, Park)
What is passive remote sensing?
It is the collection of data using sensors that measure natural radiation from the earth
What are the limitations of passive remote sensing?
Natural radiation does not penetrate clouds, smoke or rain
What types of information can both Passive and Active remote sensing get about the earth?
Temperature, soil type, land use ect.
What is Active remote sensing?
Satellite systems send out their own radiation towards the land, sensors then measure radiation which is sent back from Earth.
Are there any limitations to Active remote sensing?
No, it can get data at anytime, and can penetrate clouds, rain and smoke.
