4. From…
A Met hodology t o consider
…photograph…
…to orthophoto map…
…to
topographic map
5. What is a phot ograph?
A det ailed and complet e pict ur e
of a sect ion of realit y.
Types of phot ographs
• Hor izont al or t err est r ial
• Sat ellit e I mage
• Aerial Phot ography
Photographs
9. To orient at e yourself is t o est ablish your posit ion
• “oriens” (Lat in) - rising of t he sun or east
• f ind dist inct ive landmarks and
correlat e phot ograph wit h act ual landscape
• orientation in terms of direction -
cardinal points of the compass
• in South Africa shadows fall to the south
Orientation
12. What is a map?
A map is a generalised and reduced
represent at ion of (a port ion of ) t he
curved surface of t he eart h on a flat
surface
Or t hophot o Map
• a combinat ion of an aerial
phot ograph and a map
• a rect if ied image and t rue t o scale
Orthophoto Maps
How does t he ort hophot o map dif f er f rom
t he vert ical aerial phot ograph?
13. • A let t er or symbol indicat ing a part icular f eat ure
What is a convent ional sign?
Conventional Signs (1)
Point Line Area
14. Conventional Signs (2)
Making it easier:
Dist inguish bet ween t wo t ypes of landscape:
• t he nat ural / physical landscape
• t he const ruct ed / human landscape
• Five colours
- Brown
- Blue
- Green
- Black
- Red
28. A B
C D
A B
C D
A B
C D
18° 00’
18° 00’
34° 00’ 34° 00’
19° 00’
19° 00’
35° 00’ 35° 00’
30’
30’15’ 45’
15’
45’
3418
1° = 60’
1° Square
Reference numbering – 1:50 000
29. 18° 45’
34° 00’
19° 00’
34° 15’
03’
51’ 54’ 57’
06’
09’
12’
48’
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
16 17 18 19 20
21 22 23 24 25
Reference numbering – 1:10 000
A
C D
A B
C D
18° 00’
34° 00’
B
30. • 1° =
60’
• 1’ = 60” 30”
20”10” 40”50”
30”
10”
20”
40”
50”
01’
46’ 26° 46’ S;
29° 01’ E
26° 45’ 12” S;
29° 00’ 41” E
Co- ordinates: from ° to ‘ to “
32. 1:50 000
• This is a mat hemat ical way
of expressing t he scale
• Only numbers are used and it ref ers t o
t he same unit of measurement
Numerator
• The numerat or is always 1
& represent s t he map
Ratio Scale
Denominator
• The denominat or is always bigger
& represent s t he ground
33. map dist ance in cm ground dist ance equivalent i.e. 50 000
100 000
E.g. 3,7 cm on t he
t opographic map
3,7 x 50 000
100 000
= 1,85 km
• To convert cm t o km you must divide by 100 000 (1km = 100
000 cm)
• Conver t ing dist ance on t he 1:50 000
t opographic map:
x
1:10 000
ort hophot o map
10 000
Converting cm to km
3,7 x 10 000
100 000
= 0,37km or 370m
E.g. 3,7 cm on t he
ort hophot o map