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Extracting the most from satellite radar data.

SqueeSAR™ is the latest algorithm developed by TRE for processing satellite radar data to produce quantitative ground deformation maps. Learn more about the SqueeSAR™ algorithm.

SqueeSAR™ results can be visualized as maps of ground deformation (for an overview of ground motion over the entire area processed) or as time-series of individual ground point displacements.

Deformation maps can be easily imported and visualized in ArcGIS. Learn more about map visualization.

The two principle results of SqueeSAR™ analysis are:

  • Average velocity map
  • Time Series (for each measurement point)

For each data delivery, the position of each measurement point (latitude, longitude, elevation) and standard deviation map are provided with the SqueeSAR™ database.

In addition to the principle results, the following SqueeSAR™ maps can also be provided according to the ground movement expected and interest in particular features: 

  • Cumulative displacement
  • Average acceleration
  • Periodic variation (seasonality) amplitude
  • Differential displacement

Below is a description of the individual maps:
 

Click here to expand contentClick here to collapse content  Average Velocity

The average velocity field is used to map the average displacement rate of each ground point identified in SqueeSAR™ analysis over the time period of satellite imagery analyzed. By analyzing the cumulative displacement and average velocity fields it is possible to identify and map areas of subsidence, uplift and stability.

The color scale applied to the image is calculated according to the maximum and minimum data values. In analyzing all SqueeSAR™ data fields, ground displacement behavior can be detected and characterized.

Example: average velocity map

Click here to expand contentClick here to collapse content  Time Series

A time series is provided for each ground measurement point identified with SqueeSAR™ analysis. Time series describe the evolution of displacement over the entire analyzed period - information that cannot be extracted solely from analysis of the average velocity, cumulative displacement or average acceleration field.

Each point on a time series corresponds to a single satellite acquisition. Analyzing a time series, it is possible to identify non-linear movement, seasonal trends, ground acceleration and detect sharp changes in movement.

Example: time series

Click here to expand contentClick here to collapse content  Elevation

Maps of elevation are provided for each ground measurement point obtained from SqueeSAR™ analysis. The color scale is calculated according to the maximum and minimum data values and represents elevation with respect to the ellipsoid model WSG84.

Elevation values are particularly useful in Single Building and infrastructure stability analysis in understanding the position of measurement points on a structure.

Examples: elevation and elevation - single building

Click here to expand contentClick here to collapse content  Standard Deviation

Each measurement calculated from SqueeSAR™ data has an associated standard deviation value. The standard deviation is a measurement of the dispersion of an estimated value and provides an idea of how reliable each individual point is – the lower the value, the more reliable the information provided.

The color scale applied to the image is calculated according to the maximum and minimum data values. As a general rule of thumb, as with most common geodetic networks, the standard deviation increases the further its position from the chosen reference point. 

Example: standard deviation

Click here to expand contentClick here to collapse content  Cumulative Displacement

The cumulative displacement field is used to map the total displacement that has occurred from the first satellite image acquired, to any sequential acquisition (from the second to the last). Cumulative displacement maps allow the evolution of subsidence, uplift and stability to be characterized over time.

The color scale applied to the image is calculated according to the maximum and minimum data values. In analyzing all SqueeSAR™ data fields, ground displacement behavior can be detected and characterized.

Example: cumulative displacement map

Click here to expand contentClick here to collapse content  Average Acceleration

The acceleration field maps the average change in velocity over the time period of satellite imagery analyzed, for each ground measurement point identified. The acceleration field highlights areas affected by increasing or decreasing rates of velocity.

The color scale applied to the image is calculated according to the maximum and minimum data values. In analyzing all SqueeSAR™ data fields, ground displacement behavior can be detected and characterized. 

Example: average acceleration map

Click here to expand contentClick here to collapse content  Periodic Variation (Seasonality) Amplitude

The periodic variation amplitude (or seasonality amplitude) highlights areas within the data that exhibit cyclic behavior. The seasonality field allows the identification of periodic displacements and seasonal deformation that may not be visible in other data fields.

The color scale applied to the image is calculated according to the maximum and minimum data values. In analyzing all SqueeSAR™ data fields, ground displacement behavior can be detected and characterized.

Example: periodic variation (seasonality) amplitude

Click here to expand contentClick here to collapse content  Differential Displacement

Maps of differential displacement allow displacements that have occurred between two single satellite acquisitions (two discreet time periods) to be mapped and analyzed. This process can be performed for each image pair in a data set and is useful for the identification of spatial distribution of discreet displacement events.

Color scale is calculated according to the maximum and minimum data values.

Example: differential displacement
Executive and Processing Reports

TRE provides two reports with each data delivery:

Executive Report:

  • Scope of project description
  • Breakdown of features of interest within the results
  • Description of measurement points identified
  • Details of reference point used for analysis

Processing Report:

  • Technical details from data processing
  • Details of satellite images used
  • Satellite line of sight (LOS) summary

Executive and Processing Reports
 

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<strong>Cumulative Displacement</strong><br>Image shows the cumulative displacement measured over the entire time period of satellite imagery analyzed, for each ground measurement point identified. in SqueeSAR™ analysis. Color scale is calculated according to the maximum and minimum data values. Visualizing the cumulative displacement and average velocity, it is possible to identify and map areas affected by movement.<br><br>Analyzing all the SqueeSAR™ data fields, ground displacement behavior can be detected and characterized.<br><br>Background image: multi image reflectivity map.
 		<strong>Average Acceleration</strong><br>Image shows the acceleration measured over the time period of satellite imagery analyzed for each ground measurement point identified. Color scale is calculated according to the maximum and minimum data values. The acceleration field highlights areas affected by increased or decreased rates of velocity.<br><br>Analyzing all the SqueeSAR™ data fields, ground displacement behavior can be detected and characterized.<br><br>Background image: multi image reflectivity map.
 		<strong>Periodic Variation (Seasonality) Amplitude</strong><br>Image shows the periodic variation amplitude (or seasonality) measured over the time period of satellite imagery analyzed for each ground measurement point identified. Color scale is calculated according to the maximum and minimum data values. The seasonality field allows the identification of periodic displacements and seasonal deformation that may not be visible in other data fields.<br><br>Analyzing all the SqueeSAR™ data fields, ground displacement behavior can be detected and characterized.<br><br>Background image: multi image reflectivity map.
 		<strong>Comparison of Principle Fields of Analysis</strong><br>Image shows a comparison between the four principle fields used for SqueeSAR™ results analysis: average velocity, cumulative displacement, average acceleration and periodic variation (seasonality) amplitude.<br><br>Analyzing all four images allows a wide range of ground motion to be detected, from differential movements to cyclic, and both temporal and spatial ground deformation can be characterized.<br><br>Background image: multi image reflectivity map.
<strong>Differential Displacement</strong><br>Image shows the differential displacement that has occurred between two single image acquisitions. Color scale is calculated according to the maximum and minimum data values. Differential displacement maps allow displacements between two discreet time periods to be mapped and analyzed. This process can be performed for every image pair in the data set, and is useful for the identification of spatial distribution of discreet displacement events.<br><br>Analyzing all the SqueeSAR™ data fields, ground displacement behavior can be detected and characterized.<br><br>Background image: multi image reflectivity map.
 		<strong>Time Series</strong><br>Image shows a displacement time series of a single ground measurement point. A time series is provided for every ground measurement point identified in a SqueeSAR™ analysis. Time series describe the evolution of displacement over the entire analyzed period - information that cannot be extracted solely from analysis of the average velocity, cumulative displacement or average acceleration field.<br><br>Each point on a time series corresponds to a single satellite acquisition. It is possible to identify non-linear movement, seasonal trends, ground acceleration, detect sharp changes in movement, etc.
 		<strong>Standard Deviation</strong><br>Image shows a velocity standard deviation map resulting from SqueeSAR™ analysis. Every measurement calculated has an associated standard deviation value. The standard deviation is a measurement of the dispersion of an estimated value.<br><br>Background image: multi image reflectivity map.
 		<strong>Elevation</strong><br>Image shows the elevation of each ground measurement point obtained from SqueeSAR™ analysis. Color scale is calculated according to the maximum and minimum data values and represent elevation with respect to the ellipsoid model WSG84. Elevation values are particularly useful in <a href='http://www.treuropa.com/Home2011/Urban/SingleBuildings/tabid/314/Default.aspx'>Single Building</a> and infrastructure stability analysis in understanding the position of measurement points on a structure.<br><br>Background image: multi image reflectivity map.
<strong>Elevation - Single Building</strong><br>Image shows the elevation of ground measurement points obtained from SqueeSAR™ analysis over the Duomo, Milano. Color scale is calculated according to the maximum and minimum data values and represent elevation with respect to the ellipsoid model WSG84. Elevation values are particularly useful in single building stability analysis in understanding the position of measurement points on a structure.<br><br>Data: TerraSAR-X (Feb 2008 - Sep 2010). Background image: Google Earth.