mapwork booklet - hs elspark -germiston south africa

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INDEX

1. WHAT IS A MAP? 3 2. FEATURES ON A MAP 3 Name of a map 4 Scale of a map 4 Direction 5 Conventional signs 5 3. HEIGHT ON MAPS 6 4. ORTHOPHOTO MAP 7 Types of aerial photographs 7 How orthophotos are made 8 Shadows on orthophoto maps 8 5. TOPOGRAPHICAL MAP 9 Natural features and constructed features 9 6. INFORMATION ON AERIAL PHOTOGRAPHS AND MAPS 9 7. MAP CALCULATIONS 10 Distance 10 Area 13 Direction 15 Bearing 16 Magnetic declination 18 Magnetic bearing 20 Coordinates 21 Gradient 26 Cross section 28 Vertical exaggeration 30 Intervisibility 31 8. CONTOURS AND LANDFORMS 32 9. GEOGRAPHICAL INFORMATION SYSTEMS (GIS) 40 Definition 40 Why was GIS developed? 40 Components of GIS 40 Remote sensing 41 Types of data 43 Raster and vector data 43 Data layering 45 Buffering 46 Data integration 47 Data manipulation 48 Resolution 48 How GIS can help farmers 49 How GIS can assist development in an area 49 Map projections 50

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Types of maps

Topographic map

Orthophoto map

WHAT IS A MAP?

• A map is a symbolic representation of selected characteristics of a place,

usually drawn on a flat surface. Maps present information about the world in a

simple, visual way.

• They teach about the world by showing sizes and shapes of countries,

locations of features, and distances between places.

FEATURES ON A MAP:

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Name of the map:

The name of the map will always have the following information:

Scale of the map:

• The scale of the map indicates the relationship between the actual size of the area

and the map that has been drawn of this area.

• There are THREE types of scales:

Word scale:

Ratio scale:

Line scale:

Large scale and small-scale maps:

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Direction:

• Direction is expressed by using the points of a compass (North, East, South

and West) and the points between them.

• There are 16 cardinal points:

Key:

• A key is used to show conventional signs on a topographic map.

• Conventional signs are symbols for different features found on a map.

Three types of map symbols:

1. Line symbols: Represent lines on maps like roads, powerlines, railway

etc.

2. Point symbols: Represent point on maps like post office, police station,

buildings, shops etc.

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3. Polygon/area symbols: Represent areas on maps like dams,

recreational parks, golf courses

HEIGHT ON MAPS:

Height on maps are indicated as follows:

Trigonometrical station

Spot heights

Bench marks

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ORTHOPHOTO MAP:

Orthophoto maps are made from aerial photographs.

Types of aerial photographs:

1. Vertical aerial photographs:

• Photo is taken from an aeroplane which is flying directly over the landscape;

• Photo is taken at a 90° angle;

• Shows the top view of the landscape;

• Has a bigger scale;

• Usually printed in black and white to save costs;

• Help to map large and inaccessible areas.

2. Oblique aerial photographs:

• Photographs that are taken from high above the ground at an angle that is not

vertical to the ground.

• Two types of oblique aerial photographs:

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How orthophoto maps are made:

• Orthophoto maps are made from aerial photographs.

• Map information like the names of streets and dams are added to the

orthophoto.

• Contour lines are superimposed on the photo to provide height of the area or

landscape;

• Orthophotos maps are therefore a combination of a photo and a map;

• Digital mapping cameras are used where the camera is flown over an area and

the images are recorded and corrected according to scale;

• The scale of an orthophoto map is 1: 10 000, which means that 1 cm on

the map represent 10 000 cm on the ground.

Shadows on an orthophoto map:

• The direction of the shadow on an orthophoto map can determine the time of

the day the photo was taken.

• Always look for trees or buildings when determining the time of the day.

• The longer the shadow the earlier it is (am) and the shorter the shadow the

later in the day it is.

• Shadows that lies to the SOUTHEAST means the photo are taken after 12:00

NOT 12:00

• Shadows that lies to the SOUTHWEST means the photo are taken before

12:00 NOT 12:00

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TOPOGRAPHICAL MAP:

NATURAL FEATURES:

Any feature that appears naturally:

• Ocean, natural bays and shores;

• Islands

• Rivers, lakes and dams

• Bushes, vegetation and forests

Represented as blue areas (water resources) , brown lines ( contour lines) and green

areas (natural vegetation like bushes or forestry)

CONSTRUCTED (MAN MADE) FEATURES:

Any feature that is constructed on natural areas:

• Transport and infrastructures;

• Dam wall and dams;

• Cultivated land and purification plants;

• Buildings and heritage sites.

Represented as black and grey lines, grey areas, black symbols, green areas that

indicate cultivated lands, blue lines that indicate canals, blue symbols and red lines.

INFORMATION FROM AERIAL PHOTOGRAPHS AND MAPS:

The following information can be interpreted from photographs and maps:

• The type of landform;

• The relief of the landform;

• Drainage patterns, drainage density and drainage distribution;

• Describe the settlement type: Urban or rural;

• Describe if the settlement is nucleated or dispersed;

• Describe the site and situation of a settlement;

• Indicate what the land is being used for.

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MAP CALCULATIONS:

Distance is the shortest distance between two point in a straight line.

Answer in km Answer in m

Topographic map x 0,5 x 500

Orthophoto map x 0,1 x 100

Step 1: Measure the distance between the two points in centimeter.

Step 2: Note the unit that the answer must be in. Make use of the above table and

the following formula:

Map distance = Distance x scale

D I S TA N C E

G R 1 0 - 1 2

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EXAMPLE 1:

QUESTION: MEASURE THE DISTANCE BETWEEN THE SCHOOL AND CHURCH

IN KM.

Step 1: Measure the straight-line distance on the topographical map between

the two points.

ANSWER: 8,5 CM

Step 2: Use the table and the formula to determine the answer.

NOTE – The question asked for the distance in km.





Map distance = 8,5 cm x 0,5

Map distance = 4,25 km

We multiplied with 0,5 because the question wanted the answer in km and we worked on a

topographic map!

EXAMPLE 2:

QUESTION: MEASURE THE DISTANCE BETWEEN spot height 1706 and spot

height 1656 in m.

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Step 1 : Measure the straight line distance on the orthophoto map between the

two points.

ANSWER: 7,4 CM

Step 2: Use the table and the formula to determine the answer.

NOTE – The question asked for the distance in m.





Map distance = 7,4 cm x 100

Map distance = 740 m

We multiplied with 100 because the question wanted the answer in m and we worked on an

orthophoto map!

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The measurement of the size of a surface.

REMEMBER – WITH AREA YOU MUST MEASURE THEREFORE A SCALE MUST

BE USED!!

METHOD 1: (Answer calculated in 𝒌𝒎𝟐)

Measure the length and breadth separately… Assumed we worked on an

orthophoto map

Length = 8,5 cm

Now you have to multiply the measurement of length with the scale:




Length= Distance x scale

Length= 8,5 cm x 0,1

Length= 0,85 km

We multiplied with 0,1 because the question wanted the answer in km and we worked on an

orthophoto map!

A R E A

G R 1 1 + 1 2

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Now do the same for breadth:

Answer = 4,4 cm

Now you have to multiply the measurement of breadth with the scale:




Breadth= Distance x scale

Breadth = 4,4 cm x 0,1

Breadth = 0,44 km

We multiplied with 0,1 because the question wanted the answer in km and we worked on an

orthophoto map!

Now write down the formula to calculate area:

A = 𝒍 × 𝒃

Substitute the values calculated:

𝐴 = 0,85 𝑘𝑚 × 0,44 𝑘𝑚

𝐴 = 0,374 𝑘𝑚2

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METHOD 2: (Answer calculated in 𝒌𝒎𝟐)

We know from previous calculations that:

Length = 8,5 cm and Breadth = 4,4 cm

A = 𝒍 × 𝒃

𝐴 = (8,5 × 0,1) × (4,4 × 0,1)

𝐴 = 0,85 𝑘𝑚 × 0,44 𝑘𝑚

𝐴 = 0,374 𝑘𝑚2

Step 1: Join the two places with a line.

Step 2: Draw in the 8 main directions.

Step 3: Determine the direction.

EXAMPLE:

Determine the direction from trig beacon 153 to Bosrug.

As you can see on the map it is not one of the directions drawn on the map, therefore

it will be a direction in-between the cardinal points.

(Refer to the diagram above)

Answer = WNW

Area is ALWAYS

in 𝑘𝑚2 or 𝑚2

D I R E C T I O N

G R 1 0 - 1 2

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Step 1: Note from where the bearing must be measured.

Step 2: Draw a line between the two points.

Step 3: Place your protractor along the North – South line with the 0° at the

top.

Note the following:

If the point is anywhere from 0° − 180° you just read the

degrees from the outside of the protractor.

If the point is anywhere from 180° − 360° you have to turn the

protractor around and add the degrees to 180°.

EXAMPLE 1:

QUESTION: Determine the Bearing from point A to point B:

Step 1: Join the two points with a straight line.

B E A R I N G

G R 1 0 - 1 2

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Step 2: Draw in the North to South and West to East line at the point you must

measure FROM.

Step 3 : Place your protractor along the North – South line with the 0° at the

top.

Now read your answer from the

outer number.

Answer = 136°

EXAMPLE 2:

QUESTION: Determine the Bearing from point A to point C:

Step 1: Join the two points with a straight line.

Step 2: Draw in the North to South and West to East line at the point you must

measure FROM.

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Step 3 : Place your protractor along the North – South line with the 0° at the

top.

Remember:

When you move past 180° you

must turn your protractor and

must add the reading on the

outer side to 180°.

Answer = 180° + 67° =247°

• This is the angle between true north and the magnetic north.

• The magnetic declination changes yearly and must be calculated.

• This information can be found on the map.

• Magnetic declination can change in TWO direction:

Westerly – The magnetic declination will INCREASE.

Easterly – The magnetic declination will DECREASE.

Information on a map regarding the magnetic declination:

June 2011 refer to the month and year that the mean magnetic declination was

recorded.

June 2011 – May 2012 refers to the years that were used to calculate the mean

(average) magnetic declination. DO NOT USE THESE DATES IN CALCULATIONS!

M A G N E T I C D E C L I N AT I O N

G R 1 1 & 1 2

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Mean annual change refers to how the magnetic declination changes each year.

HOW TO DETERMINE THE MAGNETIC DECLINATION:

QUESTION: Use the information on the map and determine the magnetic

declination for 2020.

Step 1: Calculate the difference in years = Current year – Year on the map

Difference in years = 2020 – 2011

Difference in years = 9 years

Step 2: State the mean annual change:

Mean annual change: 6’ W

Step 3: Calculate the total change = difference in years x mean annual change

Total change: 9 years x 6’ W

Total change: 54’ W

Step 4: Add the total change to the magnetic declination for 2011

Magnetic declination for 2011: 26° 31’ W

Total change (2011 – 2020): 54’ W

Magnetic declination = 26° 31’ + 00° 54” W

Press the following on your calculator:

Magnetic declination = 26 31 + 00 54

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Magnetic declination = 27°25’ W (Remember the direction MUST be indicated)

QUESTION: Calculate the magnetic bearing of trig beacon 160 to trig beacon 39.

Use the following formula: Magnetic bearing = True bearing + Magnetic

declination.

Step 1: Determine the bearing between the two points.

Answer = 110°

Step 2: Use the information on the map and determine the magnetic

declination.

1. Difference in years = 2020 – 2011

Difference in years = 9 years

2. Total change: 9 years x 6’ W

Total change: 54’ W

3. Magnetic declination = 26° 31’ + 00° 54” W

M A G N E T I C B E A R I N G

G R 1 1 & 1 2

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Magnetic declination = 27°25’ W

Step 3: Use the answers and substitute it into the formula.

True bearing = 110°

Magnetic declination = 27°25’ W

Magnetic bearing = True bearing + Magnetic declination

Magnetic bearing = 110° + 27°25’W

Magnetic bearing = 137°25’ W

• Coordinates are a set of values that shows the exact location of a feature.

• Coordinates are given as degrees (°), minutes (‘) and seconds (“) and a

direction.

• Latitude and Longitude are used to give the exact position.

• In South Africa:

Latitude will ALWAYS be SOUTH therefore increase in minutes

and seconds when you move down on a map, and

C O O R D I N AT E S

G R 1 0 - 1 2

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Longitude will ALWAYS be EAST therefore increase when you

move from left to right on a map.

Remember:

• 60’ = 1°

• 60” = 1’

• With the start of a new block it changes

• to the next minute.

QUESTION: DETERMINE THE COORDINATES OF TIG BEACON 345 IN BLOCK

B1.

Note that the coordinates must be written in the following format:

00°00’00” S; 00°00’00” E

Latitude ; Longitude

Step 1: Start with the latitude. Determine the degrees.

Answer: 33°

Step 2: Determine the minutes of the latitude.

Remember when moving from block A to block B 60 seconds has passed and therefore it will

be one minute more. The degrees remain the same.

Answer: 20’

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Step 3: Now determine the seconds.

Use the following method:

1. Draw a line from the top to the point.

2. Measure the length of the line.

Answer: 2,4 cm

3. Now measure the length of the whole block B1.

Answer: 3,7 cm

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4. Now do the following calculation to determine the seconds:

Seconds = short line

long line ×

60

1

𝑆𝑒𝑐𝑜𝑛𝑑𝑠 = 2,4 𝑐𝑚

3,7 𝑐𝑚 ×

60

1

Seconds = 38,9189

𝑆𝑒𝑐𝑜𝑛𝑑𝑠 ≈ 39“

5. Now write the whole value (degrees, minutes, seconds and direction) of the

latitude:

33° 20’ 39” S

Step 4: Determine the degrees of the longitude

Answer: 25°

Step 5: Determine the minutes of the longitude.

Answer: 15’

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Step 6: Now determine the seconds.

Use the following method:

1. Draw a line from the left to the point.

2. Measure the length of the line.

Answer = 3,1 cm

3. Now measure the width(breadth) of the whole block B1.

Answer = 4,2 cm

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4. Now do the following calculation to determine the seconds:

Seconds = short line

long line ×

60

1

𝑆𝑒𝑐𝑜𝑛𝑑𝑠 = 3,1 𝑐𝑚

4,2 𝑐𝑚 ×

60

1

Seconds = 44, 2857

𝑆𝑒𝑐𝑜𝑛𝑑𝑠 ≈ 44“

5. Now write the whole value (degrees, minutes, seconds and direction) of the

longitude:

25° 15’ 44” E

6. Lastly, write the coordinates for both latitude and longitude:

Latitude; Longitude

33° 20’ 39” S ; 25° 15’ 44” E

• Gradient shows the slope of a land. It is the relationship between the vertical

height and the horizontal distance between two points.

• The following formula is used: Gradient = Vertical interval (VI)

Horizontal equivalent (HE)

• Remember that gradient is in METERS

• Answer must ALWAYS be as a ratio (1: 1)

QUESTION: DETERMINE THE GRADIENT BETWEEN TRG BEACON 345 IN

BLOCK B1 AND POINT HEIGHT 459 IN BLOCK A2. (On the topographic map)

G R A D I E N T

G R 1 1 & 1 2

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Step 1: Draw a line between the two points.

Step 2: Determine the HE (Horizontal equivalent) by subtracting the two points

from one another:

𝐻𝐸 = 697,1 𝑚 − 459 𝑚

𝐻𝐸 = 238 𝑚

Step 3: Determine the HE (Horizontal equivalent) by measuring the distance

between the two points.

Answer: 6,5 cm

Remember that you have measured to so you must multiply with the scale…

𝐻𝐸 = 6,5 𝑐𝑚 × 500

𝐻𝐸 = 3250 𝑚

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Step 4: Substitute the values calculated into the formula:

Remember to always write the formula down..

𝐆𝐫𝐚𝐝𝐢𝐞𝐧𝐭 = 𝐕𝐞𝐫𝐭𝐢𝐜𝐚𝐥 𝐢𝐧𝐭𝐞𝐫𝐯𝐚𝐥 (𝐕𝐈)

𝐇𝐨𝐫𝐢𝐳𝐨𝐧𝐭𝐚𝐥 𝐞𝐪𝐮𝐢𝐯𝐚𝐥𝐞𝐧𝐭 (𝐇𝐄)

Gradient =238 m

3250 m (Divide the numerator and the denominator by the value

of the numerator)

OR

Insert it as follow into your calculator (𝟑𝟐𝟓𝟎

𝟐𝟑𝟖)

Step 5: Write your answer as a ratio = 1 : 13,66 (Round off to two decimals)

A cross section is a SIDE view of a landform or system.

Follow the following steps to draw a cross section:

Step 1: Draw a straight line between the points.

C R O S S S E C T I O N

G R 1 0 - 1 2

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Step 2: Use a strip of paper and place it along the line:

Step 3: Mark off each contour and record its height in meters

Step 4: Draw a graph where the vertical scale is on the y-axis with a scale of 1

cm = 20m and the horizontal scale is on the x-axis.

Remember the following:

• Label your x and y axis

• Write a heading for your graph

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Step 5: Place the strip of paper on the horizontal line and plot the heights to

correspond with the heights on the vertical axis. Join the dots to

complete the cross section.

• It is difficult to distinguish the difference in the slope if the vertical and horizontal

scales are the same.

• Therefore, vertical exaggeration is the amount by which the vertical scale of the

cross section is bigger than the map scale.

• Mountain areas usually have a smaller exaggeration and flat areas have a

bigger exaggeration so that the relief difference is noticeable.

• Vertical exaggeration is calculated with the following formula:

𝑽𝑬 = 𝑽𝑺 (𝑽𝒆𝒓𝒕𝒊𝒄𝒂𝒍 𝒔𝒄𝒂𝒍𝒆)

𝑯𝑺 (𝑯𝒐𝒓𝒊𝒛𝒐𝒏𝒕𝒂𝒍 𝒔𝒄𝒂𝒍𝒆)

Step 1: Write down the vertical scale.

1 𝑐𝑚 = 20 𝑚

Step 2: Convert the meters to centimeters in the vertical scale

1 𝑐𝑚 = 20 𝑚 × 100

1 𝑐𝑚 = 2000 𝑐𝑚

Step 3: Write the VS as a fraction:

1 𝑐𝑚 = 2000 𝑐𝑚 =1

2000

V E R T I C A L E X A G G E R AT I O N

G R 1 1 & 1 2

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Step 4: Write down the scale of the horizontal axis.

Note topographic map = 1: 50 000 and orthophoto map 1: 10 000.

Let’s assume we worked on a topographic map..

1: 50 000

Step 5: Write the horizontal scale as a fraction

1: 50 000 = 1

50 000

Step 6:

Write down the formula: 𝑽𝑬 = 𝑽𝑺 (𝑽𝒆𝒓𝒕𝒊𝒄𝒂𝒍 𝒔𝒄𝒂𝒍𝒆)

𝑯𝑺 (𝑯𝒐𝒓𝒊𝒛𝒐𝒏𝒕𝒂𝒍 𝒔𝒄𝒂𝒍𝒆)

Step 7: Substitute the values for VS and HS in the formula:

𝐕𝐄 = 𝐕𝐒 (𝐕𝐞𝐫𝐭𝐢𝐜𝐚𝐥 𝐬𝐜𝐚𝐥𝐞)

𝐇𝐒 (𝐇𝐨𝐫𝐢𝐳𝐨𝐧𝐭𝐚𝐥 𝐬𝐜𝐚𝐥𝐞)

VE =

12000

150 000

VE = 1

2000 ×

50 000

1

𝐕𝐄 = 𝟐𝟓 𝐭𝐢𝐦𝐞𝐬

Refers to whenever one place is visible from another place.

To divide a

fraction you can

change the sign

to multiply and

invert the

fraction..

I N T E RV I S I B I L I T Y

G R 1 1 & 1 2

Point A is visible so there is

intervisibility.

Point B is not visible so

there is no intervisibility.

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WHAT IS A CONTOUR LINE?

A contour line is a line on a map that join all points of the same height above sea level.

CHARACTERISTICS OF CONTOUR LINES:

• Contour lines are imaginary lines;

• Contour lines can never cross one another;

• Contour lines are represented as a brown line on a 1: 50 000 topographical

map;

• Contour lines are continuous and closed lines (except if they are at the side of

the map);

• If the landscape is steep, the contour lines are close together;

• Contour intervals indicate the difference in height between successive contour

lines;

• If the landscape is gentle, the contour lines are far apart;

• If the slope is uniform, the contour lines are evenly spaced;

• Contour lines can join to form a single contour line only where there is a vertical

cliff;

• Contour lines never split.

C O N TO U RS L I N E S A N D S LO P E S

G R 1 0 - 1 2

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CONTOUR PATTERNS:

1. Gentle slopes:

• Contour lines are far apart;

• This even spacing is maintained in both up and down slope.

2. Steep slope:

• Contour lines are close together;

• This even spacing is maintained in both up and down slope

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3. Concave slope:

• When the contour lines are close together at the top of the hill and gentle at the

bottom;

• A slope which becomes progressively steeper uphill.

• On a map the Contour lines will be spaced closer with an increase in height

above sea-level.

4. Convex slope:

• When the contour lines are gentle at the top of the hill and close together at the

bottom, this indicate a convex slope;

• A slope which becomes progressively steeper downhill;

• On a map the contour lines will be spaced closer together with a decline in

height above sea-level.

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1. River valleys:

• A valley is formed due to flowing water and result into a V – shaped landform;

• The V- shape point towards the higher ground (bigger contour interval).

• In the case of a river valley, the greatest height is to the outer side and the land

sinks down towards the inner side, where the riverbed is.

L A N D F O R M S

G R 1 0 - 1 2

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2. V – valley:

• Found in the upper course of a river where the gradient is steep;

• Can be identified on a map by looking at the dominant V of the contour lines;

• Contour lines are close together.

3. U- valley:

• Occur in areas where water or glacier erosion has widened the valley floor to

make it a U shape;

• Occur in the middle and lower course of a river;

4. Waterfall:

• Forms where there is a sudden drop in the river valley;

• Waterfalls are formed in the upper course of the river;

• When contour lines on a map touch one another or are very close together as

they cross a river or stream, it indicates a waterfall.

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5. Spur:

• A long, gently sloping strip of ground that runs down from a hill to lower ground;

• A spur is formed between two river valleys;

• The greatest height is to the inner side and the land sinks down towards the

outer side of the spur.

6. Hill:

• A point or small area of high ground.

• When you are on a hilltop, the ground slopes down in all directions.

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7. Saddle:

• Depression between two peaks or ridges;

• This landform is formed by glaciers or streams that flow close to one another;

8. RIDGE:

• A line of high ground with height variations along its crest.

• The ridge is not simply a line of hills; all points of the ridge crest are higher than

the ground on both sides of the ridge.

9. MESA:

• A flat-topped hill with steep sides;

• Found in landscapes associated with horizontal strata;

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• Contour lines are close together at the top (illustrate the cap rock).

10. Butte:

• Tall flat-topped mountain with steep sides;

• Associated with landforms with horizontal strata;

• Greater height than width;

• Smaller flat top.

CONICAL HILL:

• Formed by rivers that cuts through the landscape;

• No cap rock on this type of rock;

• Rounded point at the top, but gentler than a mesa or butte.

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WHAT IS GIS?

Geographical Information Systems

DEFINITION: A computer-based technology and method for collecting, analyzing,

managing, modelling and presenting geographical data for a wide range of users.

WHY WAS GIS DEVELOPED?

To process geographical data and to produce information can be used for decision

making.

COMPONENTS OF GIS:

HARDWARE: Computer, screen, keyboard and mouse.

SOFTWARE: A program where you can enter/capture the data, edit it and put

the data into map format.

GEOGRAPHICAL DATA: Information that can be analysed.

PERSONNEL: People that can operate the computer, enter the information

and analyse the data.

METHOD: A way how the data will be stored on the computer.

WHAT IS GEOGRAPHICAL DATA?

• Information about features that exist and events that occur on Earth.

• Example: The geographical data about a residential area can explain the

population density of that area.

HOW DO WE COLLECT GEOGRAPHICAL DATA?

People complete surveys;

Use of existing data and documents and capture it on a computer;

Remote sensing;

Photographs;

Testing of natural environment e.g. testing soil and water quality;

GIS

GRADE 10 - 12

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TYPES

Active remote sensing

Send radiation out and then measures the radiation that the

earth sends back. E.g. Ocean current.

Passive remote sensing

Measure the energy that is radiated from earth. E.g.

Temperature

Physical measurements using secondary data;

Using existing maps.

REMOTE SENSING:

GR 10 - 12

DEFINITION: Collection of data by a recording device that is not in direct contact with

the area.

Examples: Satellites, aircrafts, drones and aerial photographs

TWO TYPES OF REMOTE SENSING:

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ADVANTAGES OF REMOTE SENSING:

Allows coverage of very large areas.

Can access inaccessible areas.

Easy collection of data over a variety of scales and resolutions.

There is no limitation on the extent of information that can be gathered from a

single remotely sensed image.

Data can easily be processed and analysed fast using a computer.

Does not disturb the object or the area of interest.

Cheap and fast method of collecting data of large areas.

It is easier to locate floods or forest fire that has spread over a large region

which makes it easier to plan a rescue mission easily and fast.

DISADVANTAGES OF REMOTE SENSING:

Remote sensing is a fairly expensive method of analysis especially when

measuring or analysing smaller areas.

Requires a special kind of training to analyse the images.

Human errors may occur during the analysing process.

Sometimes different phenomena being analysed may look the same during

measurement which may lead to classification error.

Sometimes large-scale engineering maps cannot be prepared from satellite

data which makes remote sensing data collection incomplete.

HOW CAN REMOTE SENSING ASSIST RESEARCHERS?

Gives an overview of the entire study area;

Allows geologists to check and verify changes over time;

Researchers do not have to be at the site to obtain data;

Weather conditions have limited influence on the obtaining of data;

Up to date data is easily and readily available;

Geologists will have access to data that could not be easily reached (obtained)

by human beings;

Data can be collected quickly;

Safer to collect data from inaccessible places;

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Continuous collection of data;

Assists with more accurate geological mapping;

Improves spectral resolution of geological mapping;

Combining different datasets of geological layers;

Studying changes in geological environments;

Collection of data is reliable.

TYPES OF DATA:

GR 11 & 12

1. SPATIAL DATA:

This data use coordinates to give an exact location of a feature.

Examples of spatial data on a map: Dams, Buildings, Rivers, Roads, House

etc.

2. ATTRIBUTE DATA:

This is descriptive data that gives the characteristics of a specific feature.

Example: Attribute data of a road might be its name, height and length.

RASTER VS VECTOR DATA:

GR 11 & 12

GIS data is stored in different ways.

RASTER DATA:

Consist of grid or cells in rows and columns called pixels.

Examples: Digital pictures from satellites and digital cameras.

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ADVANTAGES AND DISADVANTAGES OF RASTER DATA:

ADVANTAGES: DISADVANTAGES:

Complicated images can easily be

displayed.

When the image is enlarged it can be

blurry as it is made out of pixels.

Easily processed on computers. Large number of data might decrease

the processing speed.

Need a lot of space on the computer as

the image needs space for every pixel.

VECTOR DATA:

Use coordinates to specify the location of points, lines and polygon features on

a map.

POINT: LINE: POLYGON:

A point at a

particular location.

Example: School,

building and tree.

A series/line at a particular

location.

Example: River, road and

hiking trail.

A big area at a particular

location.

Example: Dam and

recreation area.

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ADVANTAGES AND DISADVANTAGES OF VECTOR DATA:

ADVANTAGE: DISADVANTAGE:

Images can be scaled without

compromising the quality of the image.

Takes a long time to create.

Easy to handle as it has a few data

items.

Some shapes like curved shapes are

not shown properly.

Easier to change/update.

DATA LAYERING:

GR 12

When different kind of data are placed on top of one another to produce a map of an

area.

Layers of maps that can be identified:

Vegetation

Drainage

Cultivation

Relief

Infrastructure (roads, railway lines, etc.)

Land-use

Built-up areas

HOW IS DATA LAYERING USED?

Different sets of data can be compared.

Relationships between different sets of data can be established.

Analyzing different sets of information.

Comparisons can assist with future developments.

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IMPORTANCE OF DATA LAYERING:

Different sets of data can be compared.

Integrated picture of landscape.

Relationships between different sets of data can be established.

Analyze different sets of information.

Comparisons can assist with future developments.

Helps with querying.

BUFFERING:

Gr 10 - 12

DEFINITION: To mark off the area around an object.

Buffer zone can be created around line, point and polygon features.

A specific distance is placed around a feature.

Buffering can be done on vector and raster data.

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ADVANTAGES: DISADVANTAGES:

Can be placed around vector and raster

data.

Can be time consuming.

Can protect the area around the feature. Can limit development in the area.

A lot of information can be gathered of

the feature in the area.

Buffers must be put on the right places

otherwise it can lead to inaccuracy.

HOW CAN BUFFERING ASSIST THE AREA WHERE THERE ARE SCHOOLS AND

RIVERS THAT PASS THROUGH THE SETTLEMENT:

Can assist with the admission to schools;

Can help to determine the number of learners in the area that must attend

school;

Help with the planning of infrastructure in the area around the school e.g. roads

and sewage pipes

Determine the average distance learners travel to school;

Ecosystems around the river can be protected;

Prevent exploitation of resources;

Prevent industrial waste to be dumped in the rivers;

Prevent pesticides from entering the river system;

Decrease the amount of soil erosion in the area;

Protect the settlement from floods in rainy seasons;

It will allow the river to maintain its natural course;

Limit the effect on the natural capacity of the river.

DATA INTEGRATION:

GR 12

DEFINITION: The integration of data from different maps into one map

which summarises the overlaying process.

Data integration makes it easier for a Geographer to analyse the information on

a map.

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PROBLEMS ASSOCIATED WITH INTEGRATING MAPS:

Maps have different scales;

Difficult to get the shapes of feature correct;

Maps have different projections;

Fieldwork information is sometimes inaccurate and incorrect.

DATA MANIPULATION:

GR 12

DEFINITION: The ability to manipulate data so that the system can perform a

wide variety of functions.

IMPORTANCE OF MANIPULATING DATA ON MAPS:

To remove unnecessary information from the map;

To use the data that is required;

Can make features lighter to be easily identified;

Making features smaller so it can be clearer;

More descriptive labels can be added;

Making images sharper in order to make it clearer.

RESOLUTION:

GR 11 & 12

DEFINITION: How clear and detailed the location and feature of a shape is.

The more cells that cover an area, the better the resolution.

A picture that was taken with an 8-megapixel camera has a better resolution

than a photo that was taken with a 4-megapixel camera.

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HOW CAN GIS HELP FARMERS?

Gr 10 -12

Determine soil type;

Determine soil fertility;

Determine drainage in the area;

Determine availability of underground water;

Determine slope of land (gradient);

Early detection of crop diseases/pests.

HOW CAN GIS ASSIST WITH DEVELOPMENT IN AN AREA?

Gr 10 -12

The person can compare the topography of the different areas to find the

topography that is most suitable;

The person can compare the soil fertility of different areas;

The person will look at the drainage of the different areas/Water for expansion;

Can determine what impact the development will have on job opportunities;

Can determine the accessibility/transport network of the newly planned

development;

The person can compare the existing aesthetic appeal of the areas of possible

development.

Determine crime rates;

Economic status of inhabitants;

Number of customers/market/threshold population;

What competition exists in the area;

Cost to build shopping centre;

Types of products to sell;

Zoning/Bylaws of municipality;

Availability of space for further development.

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MAP PROJECTIONS:

DEFINITION: The representation of the spherical surface of the Earth on a flat

map.

When maps are drawn from the spherical earth onto a flat surface the shape,

distance, area and direction change and is called distortion.

Different projections have been developed so that features can be shown

accurately.

Lines of latitude (parallels) and lines of longitudes (meridians) are used as a

base to draw the maps.

CYLINDRICAL MAP PROJECTIONS:

This kind of map projection has straight coordinate lines with horizontal

parallels crossing meridians at right angles.

All meridians are equally spaced and the scale is consistent along each

parallel.

Cylindrical map projections are rectangles, but are called cylindrical because

they can be rolled up and their edges mapped in a tube, or cylinder.

Cylindrical map projections are severely distorted at the poles.

Areas near the equator are the most likely to be accurate compared to the

actual earth.

Example: Gauss Conform projection, Mercator projection, Universal Mercator

projection and Lamberts projection.

The topographical map you are using is a Gauss Conform projection.

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CONIC MAP PROJECTIONS:

• Conic map projections are best suited for use as regional or hemispheric maps,

but rarely for a complete world map.

• The distortion in a conic map makes it inappropriate for use as a visual of the

entire Earth but does make it great for use visualizing temperate regions,

weather maps, climate projections, and more.

AZIMUTHAL MAP PROJECTION:

The only projection where the shortest distance (great circle) between any two

points is always represented by a straight line. It is neither conformal nor equal

area, and suffers from large scale distortions.

Useful for mapping areas that are roughly circular in shape.

Frequently used for air-route distance maps.

mapwork booklet - hs elspark -germiston south africa

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