第五章 SAR干涉测量(完整)第五章 SAR干涉测量(完整)中科院微波遥感

SAR干涉测量
Ground range Slant range Azimuth
A n
t e n
n a
f o o
t p r
i n t
S t r i p-m
a p
S a te ll it e o rb it
1
S a te ll it e o rb it
2
Interferometer
Baseline
Perpendicular Baseline
Interferometric system: bistatic (SRTM 2000)
y (ground range)
z
S 1
r
θ
H
S 2
P
)
exp()(0t j t u ω−c P r P r t n P j t j t u P s s /))()(()
())(exp())(exp()()(11111011r
r r
r +=+−−−∝τϕτωτc
P r P r t n P j t j t u P s s /))()(()
())(exp())(exp()()(21222022r
r r
r +=+−−−∝τϕτωτ
The SAR interferogram is generated by:
multiplying pixel by pixel the first SAR image times the second one complex conjugated.
Thus, the interferogram amplitude is the amplitude of the first image times that of the second one.
Whereas its phase (called interferometric phase) is the phase difference between the two images.
由于入射角的差异使得两幅图像不是完全重合，对它们进行配准处理后，配
SAR interferometric phase: geometric
contribution
SAR interferometric phase: geometric contribution Azimuth
S l a n t r a n g e
B r 1
r 2
A
z i m u t h G r o
u n d r a n g e
B n
r
Phase ∆≈
λ
π
4
Mt. Vesuvius, baseline 250 m.
Mt. Vesuvius, baseline 50 m.
S l a n t r a n g e
Azimuth
The role of the normal baseline The role of the normal baseline S l a n t r a n g e
Azimuth
Bn =250
The normal (or perpendicular) baseline is a key
parameter in SAR interferometry
The normal (or perpendicular) baseline is a key parameter in SAR interferometry Bn =50
⊥
−
=∆B R z 0
2sin 2
θλπ
辅图像SLC
主图像SLC
DEM
数据选择的原则：基线距与时间相干
⎪⎧
≤≤1
0,)sin(sin r µπµ距离向配
方位滤波前后方位频谱对比（a）主像滤波前；（b）辅图像滤波前；（c）主图像滤波后；（d）辅图像滤波后
A “cleaned”interferogram is achieved by averaging in areas of uniform phase. SNR improves ∝the number of looks. Usually the averaging window is adaptive.
Noise sources in interferometry
干涉相干
All images from Space Shuttle (SIR-C) span Apr-Oct
From: Rosen et al., 1996
干涉纹图干涉相干图Amplitude Phase Coherence
hundred of meters). Coherence maps cannot measure this noise.
Atmospheric artifacts can be up to two fringes. This is converted in elevation error, depending on the baseline. The error cannot be
estimated or recovered.
Atmospheric artifacts
Etna Atmospheric artifacts can be detected in a multi-baseline environment, since atmosphere is incorrelated in time.
Paris (+ reflectivity)
利用枝切法设置的枝切线
干涉纹图与利用Goldstein 算法得到的解缠结果
-3-2-10123-3-2-10
1230
10
20
30
40
50
-3
-2
-1
1
2
3
Original phase Irrotational phase
Rotational phase Unwrapped irr. phase
（a) 513×513的干涉纹图；(b)基于FFT的无权重的最小二乘算法相位解缠结果；(c)相干图；(d) Goldstein枝切法相位解缠结果
实验区1:50000地形图地理编码后的数字高程模型
新疆卡拉喀什地区三维透视图
三维透视图
±6m 90% vertical error
vertical accuracy (relative)
±16m 90% vertical error vertical accuracy (absolute)±15m 90% circular error horizontal accuracy (relative)±20m 90% circular error horizontal accuracy (absolute)16-bit Signed Integer Data format
WGS84 or MSL (optionally)Datum (vertical)WGS84
Datum (horizontal)1m Height levels 1"x1" Lon& Lat Raster size SRTM DEM Product
Salt Lake City, Utah
差分干涉测量。