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WHAT IS THIS?

Radar imagery- a type of aerospace survey carried out by radar - an active microwave sensor capable of emitting and receiving polarized radio waves reflected from the earth's surface in a certain wavelength range
Radar data processing
The main type of radar data processing is the construction of maps of vertical displacements of the earth's surface and analysis of deformations of structures.

  • Measurement of vertical displacements of a surface with an accuracy of several cm;
  • Measurement of deformations of structures and infrastructure facilities with an accuracy of several mm;
  • Establishing trends and forecasting.
Radar Differential Interferometry Technology
The technology of radar differential interferometry is based on the analysis of the phase change of signals from the same object, obtained under the same shooting conditions, but for different times. Modern approaches involve the analysis of series from a large number of radar images obtained over a period of 6 months or more.
Processing methods
Differential Interferometry (DINSAR)
Basic method of interferometric processing of radar data. At this time, it has lost its relevance, in view of the emergence of more promising methods PS and SBAS. Used for ultra high resolution pictures.
Permanent Scatterer Interferometry (PS)
It is used for territories and facilities with a developed infrastructure, it allows you to obtain time series of displacements for points that are permanent reflectors of a radar signal (elements of buildings and structures, road infrastructure facilities, etc.).
Small baseline interferometry (SBAS)
It is used for territories, objects with developed infrastructure and without, it allows to obtain time series of displacements for surface areas.
PS/SBAS
  • Radar satellites perform multiple surveys of an area with a size of 40x40 km;
  • Between repeated surveys, the phase difference is calculated, proportional to the displacements of the earth's surface and the deformation of the structures;
  • Offsets are calculated for areas of the earth's surface and objects that consistently reflect the radar signal (areas of land without forest vegetation, buildings, structures, angular landforms;
  • The result is issued in the form of a file of points / map of displacements of the radar signal, indicating the displacement values for each point / pixel as of each date of the survey (the offsets are counted relative to the date of the first in the order of the survey);
  • The accuracy of measuring displacements reaches 2 - 4 mm - the first cm;
  • It is possible to measure vertical displacements and horizontal displacements in the direction "West-East".
PERSISTENT SCATTERERS
This variant of radar interferometry is characterized by the highest possible accuracy of displacement estimation (2–4 mm in height). Input data for processing should be at least 20-25 images of the same territory for different dates, made in the same geometry of the satellite radar survey.

Algorithm:
1.Selecting the main image
2. Registration of images of the interferometric chain with an accuracy of 1/100 pixel
3. Construction of interferograms for each pair of images
4.Evaluation of the magnitude of coherence / standard deviations of the amplitude of each pair of images
5.Determination of points - stable scatterers of the radar signal
6 Estimation of phase differences and multi-time phase sweep for point targets using previously determined points
7.Application of a special filter that removes the influence of the atmosphere on the interferometric phase

The result of processing is a vector file of points, the attributes of which are written:
  • offsets for each shooting date;
  • average annual rate of displacement;
  • the total value of the displacements;
  • height above the WGS-84 ellipsoid.
Industry solutions
Agriculture
Since the end of the last century, radar sensing of agricultural crops has been used for their identification and monitoring. For it, it is necessary to take into account the radiation parameters and the properties of the reflecting surface - soil and vegetation.
Water management
Identification and classification of currents in the ocean, the formation of internal waves, the study of coastal zones.
Forestry
Active radar of the Earth's surface is successfully used for inventory and monitoring of forests, for tracing ongoing processes in the ecosystem, control of felling, fires.
Terrain analysis
One of the most priority areas for many branches of human activity: construction, industry, scientific research and geological exploration of territories.
Radar satellites
C-Band SAR
GaoFen-3
GF-3 is China's first high-resolution SAR satellite to acquire a multi-polarized SAR image with a resolution of 1-500 meters and covers a total swath of 10-650 kilometers. The satellite is capable of surveying in 12 modes of the entire surface of the earth 24 hours a day in all weather conditions.
X-Band SAR
KOMPSAT-5
The objectives of the Korea Multipurpose Satellite (KOMPSAT-5) mission are to provide SAR imagery for use in Geographic Information Systems and the Korean National Environmental and Disaster Monitoring System.
TY-SAR
Spacety deploys and operates a commercial synthetic aperture radar (SAR) constellation of 96 miniature and lightweight SAR satellites. These satellites are low cost, fast deployment, wide geographic coverage and flexible scheduling.
C-Band SAR
HiSea-1
TY-SAR Spacety satellites are commercial C-band SAR satellites. They were designed and manufactured by Spacety. The first TY-SAR satellite was named HiSea-1, which was successfully launched into orbit in December 2020.
C-band SAR
Sentinel-1A, 1B
Sentinel-1A and Sentinel-1B are European radar satellites. The first satellites launched as part of the European Space Agency's (ESA) Copernicus space program. Being in the same orbit, both satellites have the ability to capture the entire territory of the Earth within 6 days. In 2021, the launch of the Sentinel-1C satellite is planned, and in the future - Sentinel-1D.
X-диапазон
COSMO-SKYMED 1-4
COSMO-SkyMed 1–4 (Constellation of Small Satellites for Mediterranean basin Observation) X-band series of dual-use spacecraft. All satellites of the constellation are equipped with synthetic aperture radar, which allows interferometric surveying of the earth's surface with ultra-high spatial resolution (better than 1 m in the field).
SAR (X-Band)
TerraSAR-X
The satellite is equipped with the latest synthetic aperture radar, which allows radar imaging of the earth's surface with an ultra-high spatial resolution of up to 1 m, which makes the TerraSAR-X satellite system one of the most advanced Earth remote sensing instruments.
С-диапазон
Radarsat-2
Radarsat-2 represents a new generation of commercial radar satellites and was created as a result of an agreement between the government - the Canadian Space Agency, manufacturer - MacDonald, Dettwiler and Associates Ltd. (MDA), which is the operator of the satellite and ground segment.
Optimal tool for working with SAR / InSAR data
A powerful and multifunctional software package that implements a wide range of data processing methods for synthetic aperture radars (SAR), SAR interferometry (InSAR) and multi-pass SAR interferometry (Multi-Temporal InSAR).
The main characteristics of SARPROZ:
Convenient graphical interface
No coding knowledge required for standard use
Matlab based
Advanced users can develop their own software extensions very easily
Fully parallelized
SARPROZ can automatically run on multiple processor cores or computer clusters
Works on any platform
Works on any platform
Modules / variants of data processing in the SARPROZ program
SAR data processing
Correcting SLC images, aligning and calibrating SLC, calculating Reflectivity Map, highlighting point targets.
SAR interferometry (InSAR)
Orbital data processing, calculation, smoothing and filtering of the interferogram, phase sweep.
Differential SAR interferometry (DInSAR)
DTM conversion and resampling, topographic phase removal, residual phase processing, motion estimation.
Differential Interferogram Packing (SDInSAR)
Processing a series of interferograms to suppress atmospheric delays and estimate motion;
Permanent Scatterer X-ray Interferometry (PSI):
Complete data processing chain to determine the deformation of the earth's surface, surface height and estimate atmospheric delays, etc.
Case studies
Airport monitoring
Long-term monitoring of movements at the airport
3D visualization of long-term movements detected over the airport object. Sentinel-1 data was processed with Sarproz and distributed by EO59.
Landslide monitoring
Analysis of upward and downward landslides
Landslide monitoring performed by EO59 for a government agency using Sarproz. Ascending & Descending Sentinel-1 datasets, natural targets and corner reflectors.
Urban subsidence
Nonlinear analysis in urban environment
Non-linear 5-year time series in urban areas, processed by EO59 with Sarproz. Sentinel-1 data.
Hong Kong
3D image of city radar targets
80 TerraSAR-X images were processed for target detection in the city of Hong Kong. Sarproz can export results in various formats and geocode both images and point clouds.
Morandi bridge
Deformation of the Morandi Bridge
Non-linear 5-year time series in urban areas, processed by EO59 with Sarproz. Sentinel-1 data.
Shanghai
Surface subsidence detected after excavation of metro tunnels (Cosmo SkyMed data)
Yellow stripes in the image show surface subsidence caused by excavation of subway tunnels in Shanghai. The results were obtained by Sarproz using the Cosmo SkyMed image dataset.
Collapse of the building
Time series showing the harbinger of collapse in Hong Kong (TSX data)
In 2010, a building in Hong Kong suddenly collapsed. The time series processed by Sarproz shows that the building experienced well-detectable acceleration prior to collapse. The data was collected by TerraSAR-X.
HK Dam
Time series of displacement caused by the water level in the reservoir
The picture shows a dam in Hong Kong. The time series discovered by Sarproz shows that the dam has a displacement proportional to the water level in the reservoir.
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