This document discusses the differences between photogrammetry and computer vision. Photogrammetry is focused on precise geometric information extraction from imagery, while computer vision is mainly concerned with automated image understanding for tasks like object recognition and navigation. It also covers the collinearity equations used in photogrammetry to relate object points, image points, and camera orientation. Specifically, it describes how the direct linear transformation and computer vision models modify the rotation matrix to account for non-orthogonality between camera axes.
1. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
1
Direct Linear Transformation &
Computer Vision Models
Chapter 7-A4
2. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
2
Photogrammetry Vs. Computer Vision
• Conventional Photogrammetry is focusing on precise
geometric information extraction from imagery.
– Topographic mapping from space borne and airborne imagery
– Metrological information extraction through close-range
photogrammetry (terrestrial photogrammetry)
• Object-to-camera distance is less than 100meter
• Computer Vision (CV) is mainly concerned with
automated image understanding:
– Object recognition,
– Navigation and obstacle avoidance, and
– Object modeling
3. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
3
Airborne Photogrammetric Mapping
4. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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Airborne Photogrammetric Mapping
5. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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Close-Range Photogrammetric Mapping
6. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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CV: Object Recognition
7. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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CV: Navigation & Obstacle Avoidance
8. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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Photogrammetry Vs. Computer Vision
• Photogrammetry is always concerned with precise
geometric information extraction.
– Photogrammetric mapping considers potential deviations from
the assumed perspective projection.
• For Computer Vision (CV):
– Focus is always on automation.
– Object recognition and navigation applications do not require
precise derivation of geometric information.
– Depending on the application, object modeling might require
precise geometric information extraction.
– CV usually assumes that the collinearity of the object point,
perspective center, and corresponding image point is
maintained, even for un-calibrated cameras.
9. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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Object-to-Image Coordinate
Transformation in Photogrammetry
Collinearity Equations
10. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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o
a
A
oa = λ oA
These vectors should be defined w.r.t.
the same coordinate system.
Collinearity Equations
11. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
11
Oi
xc
yc
zc
A
XA
YA
ZA
a
+
(xa, ya)
R( , , )
ω φ κ
XG
YG
ZG
OG
pp
+
c
(Perspective Center)
XO
ZO
YO
Collinearity Equations
12. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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Collinearity Equations
The vector connecting the perspective center to the image point
w.r.t. the image coordinate system
o
a
−
−
−
−
−
=
−
−
−
=
=
c
dist
y
y
dist
x
x
c
y
x
dist
y
dist
x
r
v y
p
a
x
p
a
p
p
y
a
x
a
c
oa
i
0
13. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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Collinearity Equations
The vector connecting the perspective center to the object point
w.r.t. the ground coordinate system
o
A
−
−
−
=
−
=
=
o
A
o
A
o
A
o
o
o
A
A
A
m
oA
o
Z
Z
Y
Y
X
X
Z
Y
X
Z
Y
X
r
V
14. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
14
Where: λ is a scale factor (+ve).
Collinearity Equations
11 12 13
21 22 23
31 32 33
( , , )
c c m
i oa O m oA
a p x A o
a p y A o
A o
v r M V R r
x x dist m m m X X
y y dist m m m Y Y
c m m m Z Z
λ ω ϕ κ λ
λ
= = =
− − −
− − = −
− −
oA
oa λ
=
15. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
15
Collinearity Equations
c
m
R
M =
y
o
A
o
A
o
A
o
A
o
A
o
A
p
a
x
o
A
o
A
o
A
o
A
o
A
o
A
p
a
dist
Z
Z
m
Y
Y
m
X
X
m
Z
Z
m
Y
Y
m
X
X
m
c
y
y
dist
Z
Z
m
Y
Y
m
X
X
m
Z
Z
m
Y
Y
m
X
X
m
c
x
x
+
−
+
−
+
−
−
+
−
+
−
−
=
+
−
+
−
+
−
−
+
−
+
−
−
=
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
33
32
31
23
22
21
33
32
31
13
12
11
m
c
R
R =
y
o
A
o
A
o
A
o
A
o
A
o
A
p
a
x
o
A
o
A
o
A
o
A
o
A
o
A
p
a
dist
Z
Z
r
Y
Y
r
X
X
r
Z
Z
r
Y
Y
r
X
X
r
c
y
y
dist
Z
Z
r
Y
Y
r
X
X
r
Z
Z
r
Y
Y
r
X
X
r
c
x
x
+
−
+
−
+
−
−
+
−
+
−
−
=
+
−
+
−
+
−
−
+
−
+
−
−
=
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
33
23
13
32
22
12
33
23
13
31
21
11
16. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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Object-to-Image Coordinate
Transformation
Direct Linear Transformation
Computer Vision Model
17. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
17
DLT & Computer Vision Models
• The DLT and computer vision models encompass:
– Collinearity Equations,
– Non-orthogonality (α) between the axes of the image/camera
coordinate system, and
– Two scale factors (Sx, Sy) along the axes of the image
coordinate system.
• DLT & CV models can directly deal with pixel
coordinates.
• We will start with modifying the rotation matrix to
consider the impact of the non-orthogonality (α).
– Primary rotation 𝜔 @ the 𝑋-axis of the ground coord. system
– Secondary rotation 𝜑 @ the 𝑌 -axis
– Tertiary rotation 𝜅 & (𝜅 + 𝛼) @ the𝑍 -axis
18. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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Primary Rotation (ω)
X
Z
Y
& Xω
Yω
Zω
ω
19. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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Primary Rotation (ω)
=
−
=
ω
ω
ω
ω
ω
ω
ω
ω
ω
ω
ω
z
y
x
R
z
y
x
z
y
x
z
y
x
cos
sin
0
sin
cos
0
0
0
1
20. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
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Secondary Rotation (φ)
φ
Yω
Zω
Xω
Xωφ
Zωφ
& Yωφ
21. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
21
Secondary Rotation (φ)
=
−
=
φ
ω
φ
ω
φ
ω
φ
ω
ω
ω
φ
ω
φ
ω
φ
ω
ω
ω
ω
φ
φ
φ
φ
z
y
x
R
z
y
x
z
y
x
z
y
x
cos
0
sin
0
1
0
sin
0
cos
22. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
22
Tertiary Rotation (κ)
Xωφ
Zωφ
Yωφ
Yωφκ
Xωφκ
& Zωφκ
κ
κ
κ
23. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
23
Tertiary Rotation (κ)
=
−
=
κ
φ
ω
κ
φ
ω
κ
φ
ω
κ
φ
ω
φ
ω
φ
ω
κ
φ
ω
κ
φ
ω
κ
φ
ω
φ
ω
φ
ω
φ
ω
κ
κ
κ
κ
z
y
x
R
z
y
x
z
y
x
z
y
x
1
0
0
0
cos
sin
0
sin
cos
24. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
24
Rotation in Space
=
κ
φ
ω
κ
φ
ω
κ
φ
ω
κ
φ
ω
z
y
x
R
R
R
z
y
x
// to the ground coordinate system // to the image coordinate system
25. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
25
Rotation in Space
φ
ω
κ
φ
ω
κ
ω
κ
φ
ω
κ
ω
φ
ω
κ
φ
ω
κ
ω
κ
φ
ω
κ
ω
φ
κ
φ
κ
φ
κ
φ
ω
cos
cos
sin
sin
cos
cos
sin
cos
sin
cos
sin
sin
cos
sin
sin
sin
sin
cos
cos
cos
sin
sin
sin
cos
sin
sin
cos
cos
cos
:
33
32
31
23
22
21
13
12
11
33
32
31
23
22
21
13
12
11
=
+
=
−
=
−
=
−
=
+
=
=
−
=
=
=
=
r
r
r
r
r
r
r
r
r
where
r
r
r
r
r
r
r
r
r
R
R
R
R
26. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
26
Xωφ
Zωφ
Yωφ
Yωφκ
Xωφκ
& Zωφκ
κ
κ
Consideration of the Non-Orthogonality (α)
+
+
−
=
κ
φ
ω
κ
φ
ω
κ
φ
ω
φ
ω
φ
ω
φ
ω
α
κ
κ
α
κ
κ
Z
Y
X
Z
Y
X
1
0
0
0
)
cos(
sin
0
)
sin(
cos
27. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
27
+
+
−
=
κ
φ
ω
κ
φ
ω
κ
φ
ω
φ
ω
φ
ω
φ
ω
α
κ
κ
α
κ
κ
Z
Y
X
Z
Y
X
1
0
0
0
)
cos(
sin
0
)
sin(
cos
−
−
−
=
κ
φ
ω
κ
φ
ω
κ
φ
ω
φ
ω
φ
ω
φ
ω
κ
α
κ
κ
κ
α
κ
κ
Z
Y
X
Z
Y
X
1
0
0
0
sin
cos
sin
0
cos
sin
cos
Consideration of the Non-Orthogonality (α)
κ
α
κ
α
κ
α
κ
α
κ
κ
α
κ
α
κ
α
κ
α
κ
sin
cos
sin
sin
cos
cos
)
cos(
cos
sin
sin
cos
cos
sin
)
sin(
−
=
−
=
+
+
=
+
=
+
Assuming small non-orthogonality angle (α)
28. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
28
Consideration of the Non-Orthogonality (α)
−
−
=
−
−
−
1
0
0
0
1
0
0
1
1
0
0
0
cos
sin
0
sin
cos
1
0
0
0
sin
cos
sin
0
cos
sin
cos α
κ
κ
κ
κ
κ
α
κ
κ
κ
α
κ
κ
−
=
−
=
κ
φ
ω
κ
φ
ω
κ
φ
ω
κ
φ
ω
κ
φ
ω
κ
φ
ω
κ
φ
ω
α
α
Z
Y
X
R
Z
Y
X
R
R
R
Z
Y
X
1
0
0
0
1
0
0
1
1
0
0
0
1
0
0
1
29. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
29
Consideration of the Non-Orthogonality (α)
=
=
Z
Y
X
R
Z
Y
X
z
y
x
T
1
0
0
0
1
0
0
1 α
κ
φ
ω
κ
φ
ω
κ
φ
ω
// to the image coordinate system // to the ground coordinate system
−
=
κ
φ
ω
κ
φ
ω
κ
φ
ω
α
Z
Y
X
R
Z
Y
X
1
0
0
0
1
0
0
1
Note:
1 −𝛼 0
0 1 0
0 0 1
=
1 𝛼 0
0 1 0
0 0 1
30. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
30
Consideration of the Non-Orthogonality (α)
• Collinearity Equations while considering the non-
orthogonality (α) between the axes of the image
coordinate system.
−
−
−
=
−
−
−
O
O
O
T
p
p
Z
Z
Y
Y
X
X
R
c
y
y
x
x
1
0
0
0
1
0
0
1 α
λ
31. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
31
−
−
−
=
−
−
−
O
O
O
T
y
p
x
p
Z
Z
Y
Y
X
X
R
c
s
y
y
s
x
x
1
0
0
0
1
0
0
1
/
)
(
/
)
( α
λ
−
−
−
−
=
−
−
−
−
O
O
O
T
y
p
x
p
Z
Z
Y
Y
X
X
R
c
cs
y
y
cs
x
x
1
0
0
0
1
0
0
1
/
1
)
/(
)
(
)
/(
)
( α
λ
• Divide both sides by (-c).
Consideration of the Scale Factors
• Collinearity Equations while considering the non-
orthogonality (α) between the axes of the image
coordinate system & different scale factors.
32. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
32
Consideration of the Scale Factors
−
−
−
′
=
−
−
−
−
O
O
O
T
y
p
x
p
Z
Z
Y
Y
X
X
R
c
y
y
c
x
x
1
0
0
0
1
0
0
1
1
)
/(
)
(
)
/(
)
( α
λ
−
−
−
′
=
−
−
−
−
O
O
O
T
p
p
y
x
Z
Z
Y
Y
X
X
R
y
y
x
x
c
c
1
0
0
0
1
0
0
1
1
)
(
)
(
1
0
0
0
/
1
0
0
0
/
1 α
λ
−
−
−
−
−
′
=
−
−
O
O
O
T
y
x
p
p
Z
Z
Y
Y
X
X
R
c
c
y
y
x
x
1
0
0
0
1
0
0
1
1
0
0
0
0
0
0
1
)
(
)
( α
λ
• csx→ cx , csy→ cy & -λ/c → λ`.
33. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
33
DLT & Computer Vision Models
−
−
−
−
−
−
′
=
−
−
O
O
O
T
y
x
x
p
p
Z
Z
Y
Y
X
X
R
c
c
c
y
y
x
x
1
0
0
0
0
0
1
)
(
)
( α
λ
−
−
−
−
−
−
′
=
−
−
O
O
O
y
x
x
p
p
Z
Z
Y
Y
X
X
r
r
r
r
r
r
r
r
r
c
c
c
y
y
x
x
33
23
13
32
22
12
31
21
11
1
0
0
0
0
0
1
)
(
)
( α
λ
𝒙 − 𝒙𝒑
𝒚 − 𝒚𝒑
𝟏
=
𝟏 𝟎 −𝒙𝒑
𝟎 𝟏 −𝒚𝒑
𝟎 𝟎 𝟏
𝒙
𝒚
𝟏
𝟏 𝟎 −𝒙𝒑
𝟎 𝟏 −𝒚𝒑
𝟎 𝟎 𝟏
𝟏
=
𝟏 𝟎 𝒙𝒑
𝟎 𝟏 𝒚𝒑
𝟎 𝟎 𝟏
&
36. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
36
DLT & Computer Vision Models
[ ]
[ ]
3
3
'
1
1
0 { }
0 0 1
{ }
T
O
x x p
y p
T
O
X
x
Y
y K R I X
Z
c c x
K c y Calibration Matrix
R I X Exterior Orientation Matrix
λ
α
= −
− −
= − ≡
− ≡
𝑬𝒙𝒕𝒆𝒓𝒊𝒐𝒓 𝑶𝒓𝒊𝒆𝒏𝒕𝒂𝒕𝒊𝒐𝒏 𝑴𝒂𝒕𝒓𝒊𝒙 = 𝑹𝑻
𝟏 𝟎 𝟎 −𝑿𝑶
𝟎 𝟏 𝟎 −𝒀𝑶
𝟎 𝟎 𝟏 −𝒁𝑶
37. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
37
DLT & Computer Vision Models
• The Direct Linear Transformation (DLT), which has
been developed by the photogrammetric community, is
an alternative to the collinearity equations that allows for
direct transformation between machine/pixel coordinates
and corresponding ground coordinates.
– 𝑥 = & 𝑦 =
• The DLT can be also represented by the following form:
–
𝑥
𝑦
1
=
𝐿 𝐿 𝐿 𝐿
𝐿 𝐿 𝐿 𝐿
𝐿 𝐿 𝐿 𝐿
𝑋
𝑌
𝑍
1
38. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
38
DLT & Computer Vision Models
1 2 3
5 6 7
9 10 11
' 0
0 0 1
x x p
T
y p
L L L c c x
D L L L c y R
L L L
α
λ
− −
= = −
4
8
12
' 0
0 0 1
x x p O
T
y p O
O
L c c x X
L c y R Y
L Z
α
λ
− −
=− −
DLT: Direct Linear Transformation
𝐿 𝐿 𝐿 𝐿
𝐿 𝐿 𝐿 𝐿
𝐿 𝐿 𝐿 𝐿
= 𝛌 𝑲𝑹𝑻 𝑰𝟑 −𝑿𝒐
39. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
39
DLT & CV Models: Pixel Coordinates
• The DLT & CV models can also consider the direct
transformation from pixel to ground coordinates.
𝒙
𝒚
𝟏
=
𝒖 − 𝒏𝒄 𝟐
⁄ × 𝒙_𝒑𝒊𝒙_𝒔𝒊𝒛𝒆
𝒏𝒓 𝟐
⁄ − 𝒗 × 𝒚_𝒑𝒊𝒙_𝒔𝒊𝒛𝒆
𝟏
u
v
43. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
43
DLT & CV Models: Pixel Coordinates
• For DLT when working with pixel coordinates, we have
the following model.
–
𝐿 𝐿 𝐿 𝐿
𝐿 𝐿 𝐿 𝐿
𝐿 𝐿 𝐿 𝐿
= 𝛌 𝑲 𝑹𝑻 𝑰𝟑 −𝑿𝒐
•
𝐿 𝐿 𝐿
𝐿 𝐿 𝐿
𝐿 𝐿 𝐿
= 𝛌 𝑲 𝑹𝑻
•
𝐿
𝐿
𝐿
= −𝛌 𝑲 𝑹𝑻
𝑿𝒐
𝑌𝒐
𝑍𝒐
44. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
44
Modern Photogrammetry & Computer Vision
• Modern Photogrammetry and Computer Vision are
converging fields.
Art and science of tool development for automatic
generation of spatial and descriptive information from
multi-sensory data and/or systems
45. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
45
DLT → IOPs & EOPs
Approach # 1
46. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
46
DLT → IOP & EOP
1 2 3
5 6 7
9 10 11
0
0 0 1
x x p
T
y p
L L L c c x
D L L L c y R
L L L
α
λ
− −
= = −
4
8
12
0
0 0 1
x x p O
T
y p O
O
L c c x X
L c y R Y
L Z
α
λ
− −
=− −
𝐿
𝐿
𝐿
= −
𝐿 𝐿 𝐿
𝐿 𝐿 𝐿
𝐿 𝐿 𝐿
𝑋
𝑌𝒐
𝑍𝒐
47. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
47
DLT → IOP & EOP
No Sign Ambiguity
−
=
O
O
O
Z
Y
X
L
L
L
L
L
L
L
L
L
L
L
L
11
10
9
7
6
5
3
2
1
12
8
4
• Given:
• Then:
−
=
−
12
8
4
1
11
10
9
7
6
5
3
2
1
L
L
L
L
L
L
L
L
L
L
L
L
Z
Y
X
O
O
O
48. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
48
DLT → IOP & EOP
−
−
−
−
−
−
=
1
0
0
0
1
0
0
0
2
p
p
y
x
x
p
y
p
x
x
T
y
x
c
c
c
y
c
x
c
c
D
D α
α
λ
=
=
=
11
7
3
10
6
2
9
5
1
11
10
9
7
6
5
3
2
1
2
)
(
)
(
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
KK
R
K
R
K
D
D T
T
T
T
T
λ
λ
λ
2
2
11
2
10
2
9
3
3
)
( λ
=
+
+
=
× L
L
L
D
D T
}
{
2
11
2
10
2
9 Ambiguity
Sign
L
L
L +
+
±
=
λ
Then:
49. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
49
DLT → IOP & EOP
p
T
x
L
L
L
L
L
L
D
D 2
3
11
2
10
1
9
1
3
)
( λ
=
+
+
=
×
)
(
)
(
2
11
2
10
2
9
3
11
2
10
1
9
L
L
L
L
L
L
L
L
L
xp
+
+
+
+
=
No Sign Ambiguity
Then:
=
=
=
11
7
3
10
6
2
9
5
1
11
10
9
7
6
5
3
2
1
2
)
(
)
(
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
KK
R
K
R
K
D
D T
T
T
T
T
λ
λ
λ
50. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
50
p
T
y
L
L
L
L
L
L
D
D 2
7
11
6
10
5
9
2
3
)
( λ
=
+
+
=
×
DLT → IOP & EOP
)
(
)
(
2
11
2
10
2
9
7
11
6
10
5
9
L
L
L
L
L
L
L
L
L
yp
+
+
+
+
=
No Sign Ambiguity
Then:
=
=
=
11
7
3
10
6
2
9
5
1
11
10
9
7
6
5
3
2
1
2
)
(
)
(
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
KK
R
K
R
K
D
D T
T
T
T
T
λ
λ
λ
51. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
51
)
(
)
( 2
2
2
2
7
2
6
2
5
2
2 y
p
T
c
y
L
L
L
D
D +
=
+
+
=
× λ
DLT → IOP & EOP
=
=
=
11
7
3
10
6
2
9
5
1
11
10
9
7
6
5
3
2
1
2
)
(
)
(
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
KK
R
K
R
K
D
D T
T
T
T
T
λ
λ
λ
5
.
0
2
2
11
2
10
2
9
2
7
2
6
2
5
)
(
−
+
+
+
+
= p
y y
L
L
L
L
L
L
c
No Sign Ambiguity
Then:
52. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
52
DLT → IOP & EOP
)
(
)
( 2
7
3
6
2
5
1
2
1 p
p
y
x
T
y
x
c
c
L
L
L
L
L
L
D
D +
=
+
+
=
× α
λ
=
=
=
11
7
3
10
6
2
9
5
1
11
10
9
7
6
5
3
2
1
2
)
(
)
(
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
KK
R
K
R
K
D
D T
T
T
T
T
λ
λ
λ
−
+
+
+
+
= p
p
y
x y
x
L
L
L
L
L
L
L
L
L
c
c
)
(
/
1 2
11
2
10
2
9
7
3
6
2
5
1
α
No Sign Ambiguity
Then:
53. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
53
)
(
)
( 2
2
2
2
2
2
3
2
2
2
1
1
1 p
x
x
T
x
c
c
L
L
L
D
D +
+
=
+
+
=
× α
λ
DLT → IOP & EOP
=
=
=
11
7
3
10
6
2
9
5
1
11
10
9
7
6
5
3
2
1
2
)
(
)
(
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
KK
R
K
R
K
D
D T
T
T
T
T
λ
λ
λ
5
.
0
2
2
2
2
11
2
10
2
9
2
3
2
2
2
1
)
(
−
−
+
+
+
+
= p
x
x x
c
L
L
L
L
L
L
c α
No Sign Ambiguity
Then:
54. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
54
DLT → IOP & EOP
• Given:
• Then:
φ
λ
λ sin
13
9 =
= r
L
Sign Ambiguity
−
−
−
=
33
23
13
32
22
12
31
21
11
11
10
9
7
6
5
3
2
1
1
0
0
0
r
r
r
r
r
r
r
r
r
y
c
x
c
c
L
L
L
L
L
L
L
L
L
p
y
p
x
x α
λ
55. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
55
Collinearity Equations
• Objective: Resolve the sign ambiguity in λ
• Since the scale factor is always +ve
• Assuming that the origin (0, 0, 0) is visible in the
imagery
ve
Z
Z
r
Y
Y
r
X
X
r O
O
O −
−
+
−
+
− )
(
)
(
)
( 33
23
13
ve
Z
r
Y
r
X
r O
O
O −
−
−
− 33
23
13
−
+
−
+
−
−
+
−
+
−
−
+
−
+
−
=
−
−
−
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
33
23
13
32
22
12
31
21
11
O
O
O
O
O
O
O
O
O
p
p
Z
Z
r
Y
Y
r
X
X
r
Z
Z
r
Y
Y
r
X
X
r
Z
Z
r
Y
Y
r
X
X
r
S
c
y
y
x
x
56. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
56
DLT → IOP & EOP
• By choosing L12 = 1.
12 13 23 33
13 23 33
13 23 33
( )
1 ( )
1
( )
O O O
O O O
O O O
L r X r Y r Z
r X r Y r Z
r X r Y r Z
λ
λ
λ
=− + +
= − − −
=
− − −
λ is Negative
2
11
2
10
2
9 L
L
L +
+
−
=
λ
−
−
−
−
=
O
O
O
T
p
y
p
x
x
Z
Y
X
R
y
c
x
c
c
L
L
L
1
0
0
0
12
8
4 α
λ
57. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
57
DLT → IOP & EOP
• No sign Ambiguity
2
11
2
10
2
9
9
13
9
sin
sin
L
L
L
L
r
L
+
+
−
=
=
=
φ
φ
λ
λ
58. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
58
DLT → IOP & EOP
φ
ω
λ
λ
φ
ω
λ
λ
cos
cos
cos
sin
33
11
23
10
=
=
−
=
=
r
L
r
L
11
10
tan
L
L
−
=
ω
No Sign Ambiguity
−
−
−
=
33
23
13
32
22
12
31
21
11
11
10
9
7
6
5
3
2
1
1
0
0
0
r
r
r
r
r
r
r
r
r
y
c
x
c
c
L
L
L
L
L
L
L
L
L
p
y
p
x
x α
λ
59. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
59
DLT → IOP & EOP
−
−
−
=
−
−
−
=
−
1
0
0
0
1
0
0
0
1
11
10
9
7
6
5
3
2
1
33
32
31
23
22
21
13
12
11
33
23
13
32
22
12
31
21
11
11
10
9
7
6
5
3
2
1
p
y
p
x
x
p
y
p
x
x
y
c
x
c
c
L
L
L
L
L
L
L
L
L
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
y
c
x
c
c
L
L
L
L
L
L
L
L
L
α
λ
α
λ
• Retrieve κ
• Note: There is an ambiguity in 𝜅 determination (±𝜅 cannot
be distinguished).
φ
κ cos
cos 11
r
=
60. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
60
DLT → IOP & EOP
Approach # 2: Matrix Factorization
61. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
61
DLT → IOP (Factorization # 1)
• Conceptual basis: Direct derivation of the calibration matrix
• Cholesky Decomposition of DDT→ λK (Calibration Matrix)?
Wrong
−
−
−
−
−
−
=
=
=
=
1
0
0
0
1
0
0
0
)
(
)
(
2
11
7
3
10
6
2
9
5
1
11
10
9
7
6
5
3
2
1
2
p
p
y
x
x
p
y
p
x
x
T
T
T
T
T
T
y
x
c
c
c
y
c
x
c
c
D
D
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
KK
R
K
R
K
D
D
α
α
λ
λ
λ
λ
62. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
62
1
1
)
(
−
−
=
=
N
M
M
M
N
CHO
T T
M
M
T
D
D
N = T
K
λ
K
λ
T
T
T
K
K
M
M
N
M
M
N
2
1
1
1
λ
=
=
=
−
−
−
1
1
)]
}
({
[ −
−
= T
DD
CHO
K
λ
T
K
λ
K
λ
DLT → IOP (Factorization # 2)
63. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
63
−
−
−
=
−
−
−
=
−
1
0
0
0
1
0
0
0
1
11
10
9
7
6
5
3
2
1
33
32
31
23
22
21
13
12
11
33
23
13
32
22
12
31
21
11
11
10
9
7
6
5
3
2
1
p
y
p
x
x
p
y
p
x
x
y
c
x
c
c
L
L
L
L
L
L
L
L
L
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
y
c
x
c
c
L
L
L
L
L
L
L
L
L
α
λ
α
λ
• Using the rotation matrix R, one can derive the individual
rotation angles ω, φ and κ.
DLT → Rotation Angles
64. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
64
Analysis
65. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
65
Perspective Center
• (XO, YO , ZO) is the intersection point of three different
planes whose surface normals are (L1, L2, L3), (L5, L6, L7)
and (L9, L10, L11), respectively.
𝐿
𝐿
𝐿
= −
𝐿 𝐿 𝐿
𝐿 𝐿 𝐿
𝐿 𝐿 𝐿
𝑋
𝑌
𝑍
𝐿 𝑋 + 𝐿 𝑌 +𝐿 𝑍 = −𝐿
𝐿 𝑋 + 𝐿 𝑌 +𝐿 𝑍 = −𝐿
𝐿 𝑋 + 𝐿 𝑌 +𝐿 𝑍 = −𝐿
66. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
66
Perspective Center
−
−
−
=
33
23
13
32
22
12
31
21
11
11
10
9
7
6
5
3
2
1
1
0
0
0
r
r
r
r
r
r
r
r
r
y
c
x
c
c
L
L
L
L
L
L
L
L
L
p
y
p
x
x α
λ
• Assuming:
– xp ≈ 0.0 and yp ≈ 0.0
– -αcx ≈ 0.0
−
−
−
−
−
−
=
33
23
13
32
22
12
31
21
11
11
10
9
7
6
5
3
2
1
r
r
r
r
c
r
c
r
c
r
c
r
c
r
c
L
L
L
L
L
L
L
L
L
y
y
y
x
x
x
λ
• The three surfaces are orthogonal to each other.
– This would lead to better intersection.
67. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
67
−
−
−
=
33
23
13
32
22
12
31
21
11
11
10
9
7
6
5
3
2
1
1
0
0
0
r
r
r
r
r
r
r
r
r
y
c
x
c
c
L
L
L
L
L
L
L
L
L
p
y
p
x
x α
λ
• Assuming:
– xp ≠ 0.0 and yp ≠ 0.0
– -αcx ≈ 0.0
+
−
+
−
+
−
+
−
+
−
+
−
=
33
23
13
33
32
23
22
13
12
33
31
23
21
13
11
11
10
9
7
6
5
3
2
1
r
r
r
r
y
r
c
r
y
r
c
r
y
r
c
r
x
r
c
r
x
r
c
r
x
r
c
L
L
L
L
L
L
L
L
L
p
y
p
y
p
y
p
x
p
x
p
x
λ
• As xp and yp increase, the surface normals become almost
parallel.
– This would lead to weak intersection.
Perspective Center
68. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
68
• The rows of D are not correlated:
– They are orthogonal to each other.
• L-1 is well defined.
−
−
−
=
−
1
0
0
0
1
11
10
9
7
6
5
3
2
1
33
32
31
23
22
21
13
12
11
p
y
p
x
x
y
c
x
c
c
L
L
L
L
L
L
L
L
L
r
r
r
r
r
r
r
r
r α
λ
• Assuming:
– xp ≈ 0.0 and yp ≈ 0.0
– -αcx ≈ 0.0
−
−
−
−
−
−
=
33
23
13
32
22
12
31
21
11
11
10
9
7
6
5
3
2
1
r
r
r
r
c
r
c
r
c
r
c
r
c
r
c
L
L
L
L
L
L
L
L
L
y
y
y
x
x
x
λ
Rotation Angles
69. CE 59700: Digital Photogrammetric Systems Ayman F. Habib
69
−
−
−
=
−
1
0
0
0
1
11
10
9
7
6
5
3
2
1
33
32
31
23
22
21
13
12
11
p
y
p
x
x
y
c
x
c
c
L
L
L
L
L
L
L
L
L
r
r
r
r
r
r
r
r
r α
λ
• Assuming:
– xp ≠ 0.0 and yp ≠ 0.0
– -αcx ≈ 0.0
+
−
+
−
+
−
+
−
+
−
+
−
=
33
23
13
33
32
23
22
13
12
33
31
23
21
13
11
11
10
9
7
6
5
3
2
1
r
r
r
r
y
r
c
r
y
r
c
r
y
r
c
r
x
r
c
r
x
r
c
r
x
r
c
L
L
L
L
L
L
L
L
L
p
y
p
y
p
y
p
x
p
x
p
x
λ
• The rows of D tend to be highly correlated.
• L-1 is not well defined.
Rotation Angles