viith international scientific and technical conference from imagery to map: digital photogrammetric...
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VIIth International Scientific and Technical Conference From Imagery to Map: Digital Photogrammetric Technologies
Master class:Master class:Photogrammetric processing of Photogrammetric processing of pushbroom satellite imagespushbroom satellite images
Petr S. Titarov, Software Developer
September 17-20, 2007, Nessebar, Bulgaria
Master class layoutMaster class layout
Pushbroom imagery acquisitionPushbroom imagery acquisition Pushbroom imaging modesPushbroom imaging modes Pushbroom stereopairs acquisition methodsPushbroom stereopairs acquisition methods Pushbroom images blocksPushbroom images blocks Parameters of pushbroom imaging systemsParameters of pushbroom imaging systems
I. Basics of space pushbroom imagingI. Basics of space pushbroom imaging
Photogrammetric processing problemsPhotogrammetric processing problems Methods of pushbroom photogrammetryMethods of pushbroom photogrammetry
II. Pushbroom photogrammetryII. Pushbroom photogrammetry
Systems of resolution 1 meter and betterSystems of resolution 1 meter and better Systems of resolution about 2 metersSystems of resolution about 2 meters Systems of resolution 5 metersSystems of resolution 5 meters Systems of resolution 10-20 metersSystems of resolution 10-20 meters
III. Pushbroom imaging systems overviewIII. Pushbroom imaging systems overview
V. Satellite pushbroom imagery processing using PHOTOMODV. Satellite pushbroom imagery processing using PHOTOMOD
IV. Taking choice of remote sensing product for photogrammetryIV. Taking choice of remote sensing product for photogrammetry
PartPart II
Pushbroom imagery acquisitionPushbroom imagery acquisition
Pushbroom imaging modesPushbroom imaging modes
Pushbroom stereopairs acquisition methodsPushbroom stereopairs acquisition methods
Pushbroom images blocksPushbroom images blocks
Parameters of pushbroom imaging systemsParameters of pushbroom imaging systems
Basics of space pushbroom imagingBasics of space pushbroom imaging
Pushbroom image acquisitionPushbroom image acquisition
Line-by-line (pushbroom)
Pixel by pixel (whiskbroom)
Geometry of pushbroom imagery significantly differs from central projection one,Geometry of pushbroom imagery significantly differs from central projection one,so the classical photogrammetric methods are not applicableso the classical photogrammetric methods are not applicable..
Pushbroom imaging modesPushbroom imaging modes
Synchronous pushbroom imaging modeSynchronous pushbroom imaging mode
Sensor attitude is kept constant during the image acquisition
long strips acquisition is possible
the mode simplifies image geometry
Most of current imaging systems work in a synchronous way:
IKONOS
SPOT 1-5
IRS 1C/1D/P5/P6
FORMOSAT-2
Terra
ALOS…and others.
Pushbroom imaging modesPushbroom imaging modes
Asynchronous pushbroom imaging modeAsynchronous pushbroom imaging mode
Sensor attitude is rapidly changing during the image acquisition:
to enlarge the exposure
to make vector-scenes (not parallel to the satellite track)
Asynchronous mode is incident to high-resolution imaging systems like:
EROS A
QuickBird
Pushbroom stereopairs acquisition methods Pushbroom stereopairs acquisition methods
Cross-track stereo imagingCross-track stereo imaging
Cross-track (roll) tilting possibility is required
Two similar satellites can be used
Systems implementing this way of stereo imaging are, for example
SPOT 1-5 (сенсоры HRV, HRVIR, HRG)
IRS 1C/1D
Pushbroom stereopairs acquisition methodsPushbroom stereopairs acquisition methods
Along-track stereo imaging retargeting the sensorAlong-track stereo imaging retargeting the sensor
Short time gap between the stereopair images acquisition
High satellite agility is required
Systems implementing this way of stereo imaging are, for example:
IKONOS
EROS
Pushbroom stereopairs acquisition methodsPushbroom stereopairs acquisition methods
Along-track imaging using two sensors mounted on the same Along-track imaging using two sensors mounted on the same satellitesatellite
Short time gap between the stereopair images acquisition
Constant base-to-height ratio
Long stereo strips can be acquired
SPOT 5/HRS
Cartosat-1
ALOS
Terra/ASTER
Blocks of pushbroom imagesBlocks of pushbroom images
Base-to-height ratio (B:H) in theoverlapping areas is arbitrary.
Block of single images (“monoblock”)
New (ordered) imaging
Block composed of archive images
Blocks of pushbroom imagesBlocks of pushbroom images
Block of stereopairs (“stereoblock”)
The set of overlapping stereopairs
Pushbroom imaging systems parametersPushbroom imaging systems parameters
Geometric parameters:Geometric parameters:
Example: SPOT/HRG
Ground sample distance
Swath width
Depends on: detector size focal length orbit altitude
Depends on: focal length < the two determine detectors size and count < the field of view orbit altitude tilting
Tilting capability
Depends on: sensor and satellite design
Pushbroom imaging systems parametersPushbroom imaging systems parameters
The main radiometric parametersThe main radiometric parameters
Spectral channels
Count and the wavelength range
Radiometric resolution
Dynamic range
Imaging system productivityImaging system productivity
Depends on: swath width satellite orbit tilting capability imaging mode (synchronous/asynchronous) stereoscopic imaging method on-board storage capacity parameters and placement of receiving stations
Remote sensing satellites orbitsRemote sensing satellites orbits
02
cos51cos
2
aei
iN
iN
Major semi-axis a determines the satellite altitude
Eccentricity e0 (circular orbit) constant satellite altitude
Inclination i98 (near-polar sun-synchronous orbit) almost all the Earth is observable satellite passes nodes every revolution at the same local time
Celestial longitude of the ascending node subject to perturbation
Argument of perigee does not matter for circular orbit
Secular perturbation per N revolutions:
Geo-synchronous orbit satellite track periodically repeats
Remote sensing satellites orbitsRemote sensing satellites orbits
Polar orbit Sun-synchronous orbit
Sun-synchronous orbitSun-synchronous orbit
t1
t2
t3
The sun
Satellite orbitplaneOrbit of the
Earth
The Earth t
t
t
The sun
Satellite orbitplaneOrbit of
the Earth
The Earth
PartPart IIII
Problems solved to perform photogrammetric processingProblems solved to perform photogrammetric processing Methods of pushbroom photogrammetryMethods of pushbroom photogrammetry
Pushbroom photogrammetryPushbroom photogrammetry
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),,(
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3
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kji
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r2
r1
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Orbit
Earth
G
S1
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ray 1ray 2
Space resection and space intersectionSpace resection and space intersection
GCPs
Single images
DEM3D vectors
Orthoimagery2D vectors
DEM
GCPs
Stereopairs
Ortho-mosaics
Export to GIS, CAD,
digital maps
right
right
left
left
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x
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Z
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Methods of pushbroom photogrammetryMethods of pushbroom photogrammetry
Rigorous Replacement models
Methods of pushbroom photogrammetry
Modeling imagery acquisition geometry
Using abstract relationships that approximate rigorous
imaging model
Generic
Using a-priory relationships containing parameters determined from GCPs
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),,(),,(
),,(
4
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hP
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ZCYCXC
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r2
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Orbit
Earth
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S1
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ray 1ray 2
Rigorous methodRigorous method
Ray’s edges: )(lSS
Ray’s directional vectors: ),( plrr
l – line number p – detector number
Sensor motion model: )(lSS
Ray’s directional vector: )()(),( plPplr
Attitude model: )(lPP
Sensor geometry model: )( p
Reconstruction of:
Models used:
Ray’s edge: )(lSS
Reconstructed vectors:
Sensor geometrySensor geometry ( (interior orientationinterior orientation))
Tabulated vector-function2D central projection
)( p
1
p )( p
p1
p2
1
2
The model defines the directional vector of ray sensed by the detector number p with respect to the sensor reference system S:
The model is the analog of interior orientation elements in classical photogrammetry.
Sensor motion modelSensor motion model
Polynomial modelPolynomial model Orbital modelOrbital model
Z
Y
X
n
k
kk
n
j
jj
n
i
ii
lCZ
lBY
lAX
0
0
0
Keplerian orbit parameters:• major semi-axis a • eccentricity e• inclination i• celestial longitude of the ascending node • argument of perigee • perigee passing time
Parameters to be refined:
e, i, ,, sometimes a
Parameters to be refined:
Ai , Bj , Ck
applicable in any Cartesian reference system (including ECR) simple to implement
inertial reference system must be used physical model only a few parameters to refine
Sensor attitude modelSensor attitude model
The model is defined by the three angles , , , which polynomially depend on the line number l, or it can be represented as the sum of the measured in-flight values and polynomial refinements:
K
k
kkèçì
J
j
jjèçì
I
i
iièçì
lll
lll
lll
0
0
0
)()(
)()(
)()(
The model defines the rotation of the sensorreference system with respect to the geocentricReference system.
))(),(),(()( lllPlP
Rigorous solution of space resection and space Rigorous solution of space resection and space intersection intersection
Space intersectionSpace intersection Space resectionSpace resection
Z
Y
X
fy
x
2
2
1
1
y
x
y
x
g
Z
Y
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Correspondent rays intersection Iterative process
Imagery orientationImagery orientation
0)( SMrSMr
Z
Y
X
SM
Z
Y
X
Pr
,
0
0
0
XYYX
ZXXZ
YZZY
Any two of the three equations are independent:
The image orientation is based on the collinearity condition:
GenericGeneric ( (parametricparametric) ) methodmethod
Using some a-priory equations derived from coarse assumptions concerning imaging geometry whichrelate image coordinates x, y to ground ones X,Y,Z.The values of the parameters involved into the equations are calculated using GCPs.
),...,,,,(
),...,,,,(
1
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m
n
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ppZYXfx
Direct Linear Transformation (DLT)
1
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ZCYCXC
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Parallel-perspective model
1
1
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321
4321
ZCYCXCy
ZBYBXB
AZAYAXAx
Replacement models
They are models which approximateground-to-image correspondencecalculated using rigorous method:
),,(
),,(
ZYXGy
ZYXFx
or, more often,
),,(
),,(
ZyxGY
ZyxFX
RPC = Rational Polynomial Coefficients = Rapid Positioning Capability
),,(
),,(),,(
),,(
4
3
2
1
NNN
NNNN
NNN
NNNN
hP
hPy
hP
hPx
4,1,
3
0
3
0
3
0),,(
3
qi j k
kN
jN
iNijkqhP ha
kji
NNNq
Basic relationships:
, where
N, N, hN - normalized ground coordinates:
(-1 N 1, -1 N 1, -1 hN 1)
h
hNNN s
ohh
s
o
s
o
xN, yN - normalized image coordinates:
(-1 xN 1, -1 yN 1)
y
yN
x
xN s
oyy
s
oxx
Adjustment-derived refinements:
DsDlD
DyDxD
ybxbbyy
yaxaaxx
0
0
0
0
byy
axx
D
D
или
Algebraic solution of space intersection and space resection
Space intersectionSpace intersection Space resectionSpace resection
Z
Y
X
fy
x
2
2
1
1
y
x
y
x
g
Z
Y
X
),,(),,( ZYXGyZYXFx iiii
Based on relationships:
Directly by formula
),,(
),,(
ZYXGy
ZYXFx
ii
ii
Least-squares estimation of 3 unknowns X, Y, Z from 4 non-linear equations:
0),,(
0),,(
0),,(
0),,(
22
22
11
11
ZYXGy
ZYXFx
ZYXGy
ZYXFx
PartPart IIIIII
Systems of resolution of Systems of resolution of 1 1 m or betterm or better
Systems of resolution aboutSystems of resolution about 2 2 mm
Systems of resolution Systems of resolution 5 5 mm
Systems of resolution Systems of resolution 10-20 10-20 mm
Pushbroom imaging systems overviewPushbroom imaging systems overview
Systems of resolution 1 m or betterSystems of resolution 1 m or better
Systems of resolution 1 m or betterSystems of resolution 1 m or better
Systems of resolutionSystems of resolution about about 2 2 mm
Systems of resolutionSystems of resolution 5 5 mm
Systems of resolutionSystems of resolution 10-20 10-20 mm
PartPart IVIV
Taking choice of remote sensing product for photogrammetryTaking choice of remote sensing product for photogrammetry
One should take into consideration the following aspects:
if the imagery is geometrically pre-processed
metadata contents (if it contains the image geometry)
possibility to order polygones or sub-scenes
data format
Geometric preprocessingGeometric preprocessing
Rigorous methods are not applicable to the geometrically preprocessed imagery!
Example:
Imaging systemImaging system
Geometrically rawGeometrically raw Geometrically correctedGeometrically corrected
Remote sensing productRemote sensing product
SPOT, ASTERSPOT, ASTER 1A1A 1B1B
KOMPSAT, LandsatKOMPSAT, Landsat 1R1R 1G1G
QuickBirdQuickBird BasicBasic StandardStandard
OrbView-3OrbView-3 BASICBASIC GEOGEO
Metadata contents and data file formatMetadata contents and data file format
Cartosat-1 stereopairCartosat-1 stereopair
Stereo Ortho KitStereo Ortho Kit Basic stereoBasic stereo
TIFF raster andTIFF raster and RPCRPC Super Structured file format, Super Structured file format, processing using generic methodsprocessing using generic methods
PartPart VV
Satellite pushbroom imagery processing using PHOTOMODSatellite pushbroom imagery processing using PHOTOMOD
PHOTOMOD supported sensorsPHOTOMOD supported sensors
Remote sensing product files set structureRemote sensing product files set structure
QuickBird Basic product files set
Connection between IKONOS Geo Ortho Kit product
imagery and RPC files
<image file name>.tif<image file name>.tif
<image file name>_rpc.txt<image file name>_rpc.txt
QuickBird Standard Tiled StructureQuickBird Standard Tiled Structure
QuickBird Standard and Standard Ortho Ready imagery can be tiled.
RPC refers to the composed image!
Collective processing of imagery acquired by different Collective processing of imagery acquired by different sensorssensors
Possible candidates for collective processingPossible candidates for collective processing::
SPOT-5 Supermode (2.5 m)SPOT-5 Supermode (2.5 m) FORMOSAT 2 PAN (2 FORMOSAT 2 PAN (2 m)m)
IKONOS + OrbView-3 + Kompsat-2IKONOS + OrbView-3 + Kompsat-2
++
Thank you for your attentionThank you for your attention!!