InSAR原理与实践指南：SAR干涉测量处理与解释

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InSAR Principles：Guidelines for SAR Interferometry Processing and Interpretation InSAR（Interferometric Synthetic Aperture Radar）是基于Synthetic Aperture Radar（SAR）技术的一种高级技术，能够生成高精度的数字高程模型（DEM）和地面形变监测数据。该技术通过对SAR图像进行干涉处理，获取地面形变信息。在这篇文章中，我们将对InSAR技术的基本原理、处理流程和应用进行详细介绍。 **InSAR原理** InSAR技术基于SAR技术，利用SAR图像之间的干涉现象来获取地面形变信息。SAR图像是通过雷达波束照射地面，记录地面散射回波信号生成的。InSAR技术通过对SAR图像进行干涉处理，获取地面形变信息。 **InSAR处理流程** InSAR处理流程主要包括以下几个步骤： 1. 数据准备：读取SAR图像数据，进行数据预处理，包括radiometric correction和geometric correction。 2. 干涉图像生成：将两幅SAR图像进行干涉处理，生成干涉图像。 3. 相位 unwrapping：对干涉图像进行相位 unwrapping，获取地面形变信息。 4. 蜕变监测：对地面形变信息进行分析，获取地面形变监测数据。 **InSAR应用** InSAR技术有广泛的应用前景，包括： 1. 地面形变监测：InSAR技术可以用于监测地面形变，例如地质灾害监测、矿山监测等。 2. 数字高程模型（DEM）生成：InSAR技术可以用于生成高精度的数字高程模型（DEM）。 3. 环境监测：InSAR技术可以用于环境监测，例如土壤湿度监测、植被监测等。 **InSAR技术特点** InSAR技术具有以下特点： 1. 高精度：InSAR技术可以生成高精度的数字高程模型（DEM）和地面形变监测数据。 2. 高分辨率：InSAR技术可以获取高分辨率的SAR图像，用于监测小范围的地面形变。 3. 非侵入性：InSAR技术是非侵入性的，不需要在监测区域进行实际测量。 **结论** InSAR技术是一种高级技术，能够生成高精度的数字高程模型（DEM）和地面形变监测数据。其广泛的应用前景使其在环境监测、地质灾害监测等领域具有重要意义。本文档为入门学习InSAR技术提供了详细的指南，适合初学者学习和研究InSAR技术。

TM-19 _________________________________________________________________________ InSAR Principles

A-8

1.2.2.2 The phase SAR image

The radiation transmitted from the radar has to reach the scatterers on the

ground and then come back to the radar in order to form the SAR image

(two-way travel). Scatterers at different distances from the radar (different

slant ranges) introduce different delays between transmission and reception

of the radiation.

Due to the almost purely sinusoidal nature of the transmitted signal, this

delay

is equivalent to a phase change

between transmitted and received

signals. The phase change is thus proportional to the two-way travel distance

2R of the radiation divided by the transmitted wavelength

. This concept is

illustrated in Figure 1-5.

Figure 1-5: A sinusoidal function sin

is periodic with a 2

radian period. In the

case of a relative narrow-band SAR (i.e. ERS and Envisat), the transmitted signal

can be assimilated, as a first approximation, to a pure sinusoid whose angle or

phase φ has the following linear dependence on the slant range coordinate r:

φ = 2

r/λ (where λ is the SAR wavelength). Thus, assuming that the phase of the

transmitted signal is zero, the received signal that covers the distance 2R travelling

from the satellite to the target and back, shows a phase φ = 4

radians.

However, due to the periodic nature of the signal, travel distances that differ

by an integer multiple of the wavelength introduce exactly the same phase

change. In other words the phase of the SAR signal is a measure of just the

last fraction of the two-way travel distance that is smaller than the

transmitted wavelength.

In practice, due to the huge ratio between the resolution cell dimension (of

the order of a few metres) and wavelength (~5.6 cm for ERS), the phase

change passing from one pixel to another within a single SAR image looks

random and is of no practical utility.

___________________________________________________________________Synthetic Aperture Radar basics

A-11

1.2.3 SAR resolution cell projection on the ground

The terrain area imaged in each SAR resolution cell (called the ground

resolution cell) depends on the local topography. It strongly depends on the

terrain slope in the plane perpendicular to the orbit (ground range direction),

and on the terrain slope in the azimuth direction.

The dimension of the ground resolution cell in azimuth is related to that of

the SAR resolution cell by the usual perspective deformation we experience

every day looking at surfaces from different angles (e.g. a postcard seen at

90 degrees is a line).

The dimension of the ground resolution cell in range is related to that of the

SAR resolution cell by an unusual perspective deformation. Figure 1-9

shows how slant-range is projected onto the ground.

Here five identical slant-range resolution

cells are shown. The first two cells

correspond to flat terrain and they contain

three triangles each. The third cell contains

seven of these triangles due to the positive

slope of the terrain. Finally the fourth and

fifth cells contain less than three triangles

due to the negative slope of the terrain.

Figure 1-9: Effect of terrain on the SAR image. For SAR resolution cells in the

plane perpendicular to the orbit, the part of the terrain imaged in each resolution

cell clearly depends on the topography.

As the terrain slope increases with respect to a flat horizontal surface (i.e. as

the normal to the terrain moves toward the line of sight (LOS)), the ground

resolution cell dimension in range increases. This effect is called

foreshortening. When the terrain slope is close to the radar off-nadir angle,

the cell dimension becomes very large and all the details are lost. Moreover,

when the terrain slope exceeds the radar off-nadir angle the scatterers are

imaged in reverse order and superimposed on the contribution coming from

other areas. This effect is called layover, and is sketched in Figure 1-10.

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InSAR原理与实践指南：SAR干涉测量处理与解释

Ferretti-2007-InSAR Principles

InSAR_Principles--Guidelines_for_SAR_Interferometry_processing

差分测量理论与过程 InSAR Principles and processing 来源欧空局

InSAR技术在地形变化检测中具体如何应用？请结合《欧空局InSAR基础指南：干涉SAR处理与解读入门》提供详细解释。

如何利用InSAR技术进行精确的地表形变监测？请结合《欧空局InSAR基础指南：干涉SAR处理与解读入门》具体展开。

insar技术的异同点

d-insar双轨法、三轨法、四轨法原理

InSAR技术的工作原理是什么，它如何通过SAR图像处理来精确测量地表变化，以及在地质灾害监测中有哪些具体应用案例？

请解释InSAR技术是如何工作的，以及如何通过SAR图像处理来精确测量地表变化？此外，能否举例说明InSAR在地质灾害监测中的实际应用？

InSAR技术如何实现地表微小变化的精确测量，并能应用于哪些领域？

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