Lithological and Structural
Mapping Using Satellite Data
Mohamed Abdelsalam
Missouri S&T
Vision
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Vision is the ability to recognize
shapes, patterns and colors and
to detect and estimate motion,
distance and size
The eye has evolved
independently in many animals
groups such as the composite eye
of insects and that of our own
The perceptual ability of human
beings are learned entirely
through experience
Vision - The structure of the
Eye
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The cornea for refraction
The iris for controlling the pupil
diameter to control the amount
of light gathered and the depth of
field
The lens with 17 mm focal length
to adjust focus for objects at
different distances
The retina (180˚ field of view) is a
light-sensitive spherical surface
where inverted image are formed
through receptors known as rods
(130 million) for black and white
images) and cones (7 million for
color images)
www.vrmny.com/anatomy.htm
Rods and Cones
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Rods peaks at about 20˚ away
from the fovea and gradually fall
off in number towards the edge
of the retina
Cones contains pigments
sensitive to red, green and blue
and are concentrated
immediately around the fovea
The blind spot where the optic
nerve leaves the eye (the blind
spot) there are neither rods nor
cones
Electromagnetic Spectrum
Additive Primary Colors
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Additive primary colors:
– Red
– Green
– Blue
In equal portions other spectral color
are produced:
– Red+Green=Yellow
– Red+Blue=Magenta
– Green+Blue=Cyan
– Red+Blue+Green=White
In non equal portions non-spectral
colors are produced
Subtractive Primary Colors
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Additive subtractive colors:
– Magenta
– Cyan
– Yellow
In equal portions other spectral color
are produced:
– Magenta+Yellow=Red
– Magenta+Cyan=Blue
– Yellow+Cyan=Green
– Magenta+Cyan+Yellow=Black
In non equal portions non-spectral
colors are produced
Hue-Saturation-Intensity
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Hue is the nature of
the color and can be
described by the
wavelength. Red = 0˚
or 360˚, green = 120˚,
and blue = 240˚
Saturation = Purity
of the color. Zero is
completely impure
and 90˚ is completely
pure
Intensity Level, or
Value is the grayscale
In 8 bit radiometric
resolution scheme,
Zero is black and 255
is white.
Hue-Saturation-Intensity
Color Cube for Additive and
Subtractive Primary Colors
Color Cube for Additive Primary
Colors and H-S-I
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Color cube for Additive additive
primary colors and H-S-I defines the
relationship between Red-Green-Blue
color space and Hue-SaturationIntensity color space
The H-S-I color space is defined by a
cone extending from black (0,0,0) to
white (255,255,255) in 8 bit
radiometric resolution scheme
The Hue is defined by an angle in
which Red=0˚ or 360˚; Green=120˚;
and Blue=240˚
Saturation ranges between 0˚ for
completely impure color and 90˚ for
completely pure color
Band 1
Band 2
Band 3
RGB color combination images
Color Triangle for Additive and
Subtractive primary Colors
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Color triangle for additive and
subtractive primary colors illustrates
the relationship between Red-GreenBlue and Magenta-Cyan-Yellow
The triangle corners are occupied by
Red, Green and Blue whereas the
mid-points between these corners are
occupied by Magenta, cyan and
Yellow
The center of the triangle is occupied
by white which resulted from the sum
of equal portions of Red, Green and
Blue
Examples
1: Density Slicing
The Beddaho
Alteration Zone,
Eritrea
Examples
2: Synthetic Color
Images
The Nubian Nile,
Sudan
SIR-C/X-SAR data
Scattering Mechanisms
Reflection
BackScattering
VolumeScattering
DoubleBounce
Smooth
Surface
Rough
Surface
Outstanding
Relief
Penetration
Paleo-channel
SIR-C/X-SAR data
Penetration
Reflected
signal from
the sand/
paleo-channel
fill interface
Refracted and
Wavelength-reduced
signal through the
air/sand interface
Reflected signal
from the
air/sand interface
Back-scattered
signal from the
sand/bedrock
interface
Fine, well sorted
dry sand
(~2 m thick)
Smooth
sand/paleo-channel
interface
Paleo-channel
(Filled with alluvium)
Complete
signal
attenuation
Rough
sand/bedrock
interface
Bedrock
(Cretaceous sandstone or
Neoproterozoic crystalline basement)
The Nile System
Did the Drainage of NE Africa
once flow to the Atlantic?
~ Oligocene (30 Ma)
Nile
Niger
Lake
MegaChad
800 km
Pres ent land above 500 m
Postulated
Trans-African Drainage
Zaire
Pres ent drainage
Modified after Burke & Wells (1989)
Examples
3: Data Fusion
The Erta Ale
Volcano, Ethiopia