UNIVERSITÀ DEGLI STUDI DI NAPOLI “FEDERICO II” FACOL TESI DI LAUREA Evaluation of geometrical parameters of buildings from SAR images RELATORE: CANDIDATO: CH.MO PROF. FEDERICO MARIA ARIU’ ANTONIO IODICE MATR. 528/1127 CORRELATORE: ING. GERARDO DI MARTINO ANNO ACCADEMICO 2009/2010
Evaluation of geometrical parameters of buildings from SAR images
Jul 05, 2015
The aim of this study is to develop a tecnique able to support the retrieval of the buildings height from SAR images.
In particular, an automatic method, which allows to evaluate the orientation angle of buildings in respect to the projection on the ground of the flight line of the radar platform, has been developed.
The starting point was the algorithm output that allows to identify and extract from SAR images the double scattering contribution whose intensity is linked to the geometrical and electromagnetic parameters of the buildings.
On SAR images, the double scattering contributions turn out to be misaligned dots, so, before evaluating the slope of the straight line of double scattering, a linear regression operation was necessary, starting from the knowledge of the coordinates of each pixel belonging to the line of double scattering.
Given the prospective presence of outliers, the absolute deviation instead of the standard deviation has been used.
In particular, an automatic method, which allows to evaluate the orientation angle of buildings in respect to the projection on the ground of the flight line of the radar platform, has been developed.
The starting point was the algorithm output that allows to identify and extract from SAR images the double scattering contribution whose intensity is linked to the geometrical and electromagnetic parameters of the buildings.
On SAR images, the double scattering contributions turn out to be misaligned dots, so, before evaluating the slope of the straight line of double scattering, a linear regression operation was necessary, starting from the knowledge of the coordinates of each pixel belonging to the line of double scattering.
Given the prospective presence of outliers, the absolute deviation instead of the standard deviation has been used.
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UNIVERSITÀ DEGLI STUDI DI NAPOLI “FEDERICO II”
FACOL
TESI DI LAUREA
Evaluation of geometrical parameters of buildingsfrom SAR images
RELATORE: CANDIDATO:CH.MO PROF. FEDERICO MARIA ARIU’ANTONIO IODICE MATR. 528/1127
CORRELATORE:ING. GERARDO DI MARTINO
ANNO ACCADEMICO 2009/2010
Summary
Introduction and goals
Models description
Developed algorithm
Results
Pros:• Image quality not depending on:Solar illuminationWeather trends
• Wide coverage area• High resolution
Cons:• Need of processing data to obtain the image
SAR images
Geometrical distorsions
Layover
Shadowing
Electromagnetic diffusionmodel
Single scattering
Electromagnetic diffusionmodel
Double scattering
EM scattering from buildings
BW=Backscattering from WallBR= Backscattering from RoofBG=Backscattering from GroundD= Double scattering
T= Triple scatteringLr =Range size of LayoverSr =Range size of ShadowS= Shadow
Scattering modelDouble scattering
)0(''2
sintanexp
)0(''2
1
cos4
sintan1
4costan
2
22
222
222
2
0
CCkS
khl
pq
2
0
22
0
4
E
ErS
θ: detector angle φ: building orientation angle in respect to the detector azimuthk: propagation constantσ2: standard deviationh: buildings height
l: buildings length
Spq: scattering matrix
Evaluation of orientationangle:usefulness
Geometrical knowledge
Geometrical and electromagnetic parameters retrieval
Height retrieval
Geometrical method:
Radiometric method:
cos
rL
h cosr
Sh
b
ah
0where
)0(''2
sintanexp
)0(''2
1
cos4
sintan1costan
2
22
222
22
CCklb
22
4
pqSk
a
Double scattering line retrieval
M
Scanning equiazimuth
ith row
Zero-Padding
correlation
Retrieval ofmaxima
Ideal sinc
Double scattering line analysis
The software returns coordinates and intensity of the dotsforming the double scattering line.
y=mx+q
m=tanα
Linear regression
Given a cloud of sampled dots, the linear regression supplies the straight line that rounds best the trend of the cloud of dots.
iiiuXY
Choosing the linearregression algorithm
The chosen algorithm minimizes minimizza lo scarto assoluto.
ABSOLUTE DEVIATION STANDARD DEVIATION
y
x
SAR images simulations: 512 x 512 SENSOR OVERVIEW
Platform height h = 20 Km
Platform speed v = 0.9 Km/s
View angle θ = 28°
Antenna dim(azimuth)
Antenna dim (range)
Carrier frequency f = 1.282 GHz
Pulse duration τ = 1.9 μs
Chirp pulse bandwidth Δf = 14 MHz
Sampling frequency fsamp = 31 MHz
Pulse repetitionfrequency
p.r.f. = 350 Hz
Azimuth resolution Δx = 2.5714 m
Range resolution Δy = 10.3067 m
mLSARx
5.8
mLSARr
5.1
SAR images simulations: 512x512 sensor
Simulation 1: φ = 10
φs = 15.0°
Simulation 2: φ = 25
φs = 26.6°
SAR images simulations: ERS-1 C SENSOR OVERVIEW
Platform height h = 775 Km
Platform speed v = 6.7 Km/s
View angle θ = 23°
Antenna dim(azimuth)
Antenna dim (range)
Carrier frequency f = 5.3 GHz
Pulse duration τ = 37.1 μs
Chirp pulse bandwidth Δf = 15.55 MHz
Sampling frequency fsamp = 18.98 MHz
Pulse repetitionfrequency
p.r.f. = 1.68 kHz
Azimuth resolution Δx = 3.9860 m
Range resolution Δy = 19.9285 m
mLSARx
1.11
mLSARr
0.1
SAR images simulations: ERS-1 C sensor
Simulation 1: φ = 10
φs = 10.1°
Simulation 2: φ = 30
φs = 30.0°
Conclusions
Pros:
• Good accuracy depending on the numbers of dotsthat belong to the line.
Cons:
• Range of angles to be evaluate low.
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