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SUR 340 Photogrammetry SUR 340 Photogrammetry Parallax 1. The following measurements were made on four different sets of adjacent left and right photographs: 5. The distance between two ground control...

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SUR 340 Photogrammetry
SUR 340 Photogrammetry
Parallax

1. The following measurements were made on four different sets of adjacent left
and right photographs:

5. The distance between two ground control points A and B is XXXXXXXXXXmeters. The
elevation of A is 208.9 meters. Parallax measurements in two adjacent photographs
containing image points a and b of the ground control points A and B are pa = 72.21
mm and pb = 74.16 mm. The coordinates of a and b in the left photo are xa = 48.28
mm and ya = 50.60 mm; xb = 67.66 mm and yb = XXXXXXXXXXmm. The focal length of the
camera is XXXXXXXXXXmm. Compute the length of the ai
ase, the flying height and the
elevation of point B.

SUR 340 Photogrammetry
SUR 340 Photogrammetry
Parallax Calculations

1. Ground Point A is imaged in two overlapping photographs as image point ( a ). The x
coordinate of Point A in the left photograph is 1.040 inches and the x’ coordinate in the
ight photograph is XXXXXXXXXXCompute the stereographic parallax of image point ( a).

inchesxxP XXXXXXXXXX' =−−=−=

2. Two overlapping photographs are set up for parallax measurement. The distance
etween the principal points ( D ) is 263.4 mm. The distance between image point ( a ) in
the left and right photos is 172.5 mm. Compute the stereographic parallax of image point
( a ).

mmdDP a XXXXXXXXXX =−=−=

3. A pair of overlapping vertical photographs was taken from a flying height of 1233 m
above sea level with a 152.4 mm focal length camera. The air base was 390 meters.
Flight light coordinates are measured as xa = 53.4 mm; ya =50.8 mm; x’a = -38.3 mm; y’a
= 50.9 mm; xb = 88.9 mm; yb = -46.7; x’b = -7.1 mm; and y’b = -46.7 mm. Calculate the
elevations of point A and B and the horizontal length of line AB.


mmp
mmp
a
XXXXXXXXXX
XXXXXXXXXX
=−−=
=−−=


levelseaabovem
p
BfHh
levelseaabovem
p
BfHh
B
a
A
614
0.96
XXXXXXXXXX
585
7.91
XXXXXXXXXX
=

−=−=
=

−=−=

m
p
yBYm
p
xBX
m
p
yBYm
p
xBX
B
B
a
a
A
a
a
A
190
0.96
7.46390;361
0.96
9.88390
216
7.91
8.50390;227
7.91
4.53390
−=

∗===∗==
=∗===∗==
XXXXXXXXXXmAB XXXXXXXXXX =−−+−=


SUR 340 Photogrammetry
SUR 340 Photogrammetry
Parallax Calculations 2

4. An overlapping pair of vertical photos was exposed with a 152.4 mm focal length
camera from a flying height of 5.320 feet above datum. Control point C has an elevation
of 865 feet above datum and the parallax of its images on the stereopair is 86.27 mm.
Calculate the air base.

XXXXXXXXXXfeet
f
phHB 522,2
4.152
XXXXXXXXXX
=

=−=

5. Images of the end points of ground line AB of length 2,131.1 feet appear on a pair of
overlapping photographs. Photocoordinates measured on the left photo were xa=33.29
mm; ya = 13.46 mm; xb = 41.76 mm; and yb = XXXXXXXXXXmm. Photocoordinates measured
on the right photo were: x’a = XXXXXXXXXXmm and x’b = XXXXXXXXXXmm. Calculate the ai
ase for
this stereopair.


( )
( ) mmxxp
mmxxp
aaa
XXXXXXXXXX
XXXXXXXXXX
'
'
=−−=−=
=−−=−=


2
1
22








⎟⎟


⎜⎜


−+⎟⎟


⎜⎜



=
a
a
a
a
p
y
p
y
p
x
p
x
ABB
feetB 1687
61.85
46.13
72.86
76.95
61.85
29.33
72.85
76.41
1.2131
2
1
22
=













⎛ −

+⎟




⎛ −
=

6. The parallax of image point ( a ) and ( c ) were measured in two overlapping vertical
photographs as 91.67 mm and 92.60 mm respectively. The elevation of Point C is known
to be 1, 938 feet above sea level. The flying height of the photographs is known to be
4,045 feet above sea level. Compute the elevation of Point C.

mmppp cb XXXXXXXXXX −=−=−=Δ


XXXXXXXXXXlevelseaabovefeet
p
hHp
hh
a
C
CA 917,167.91
XXXXXXXXXX =−−+=
−Δ
+=
Answered Same DayNov 26, 2021

Solution

Hemalatha answered on Nov 28 2021
50 Votes
SOLUTIONS
1a)Calculate the parallax for each point
Parallox
P = x − x'

Point X(left photo) X’ (right photo) Parallax, P
a 2.36 inches -1.07 inches 2.360 − (−1.07) = 3.43 inches
68.05 mm -21.61 mm 68.05 − (−21.61) = 89.66 mm =
3.53 inches
c 3.92 inches 0.39 inches 3.92 − (0.39) = 3.57 inches
d 100.37 mm 8.52 mm 100.37 − (8.52) = 91.85 mm =
3.616 inches

1b) Elevaion is given by the formula
?? = ? −
??
??

Where
H is the flying height
hA is the elevation of the given point
pa is the parallax
B is Length of Air Base
f is the focal length
The values of ‘H’, ‘B’ and ‘f’ being same for all the points, lesser the value
of (Bf)/p , higher is the value of elevation.
Again higher the value of pa , lesser is the value of (Bf)/p
Hence, the value of elevation ‘h’ will be the highest for the largest value of
parallax p.
Point‘d’ with largest value of parallax will have the highest elevation.
Point ‘a’ with the least value of parallax will have the lowest elevation.
2. Given focal length, f = 6 inches
Flying height above datum, H = 8100 feet
Ai
ase, B = 4450 feet
Elevations of points A, B, C and D respectively are hA, hB, hC and hD
h
A = H −
Bf
=...
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