19‐Sep‐18

1

1EUREF 2018

InSAR data processing

EUREF 2018 tutorial

Freek van Leijen

Delft University of Technology

2EUREF 2018

InSAR data processing flow

1Data download

2Interferometric 

processing

3Time series analysis

4Post‐

processing

19‐Sep‐18

2

3EUREF 2018

1 Data download

Unavco.org

4EUREF 2018

1 Data downloadData volumes (single polarization)

Mission Size Pixel spacing Repeat cycle Data size per product

Data size per year

TerraSAR‐X(Stripmapmode)

50x30 km ~3x3 m 11 days 1.9 GB 63 GB

Cosmo‐Skymed(Stripmapmode)

40x40 km ~3x3 m 4 days (mean)

1.7 GB 155 GB

RadarSAT‐2(Stripmap(XF) mode)

125x125 km ~3x3 m 24 days 5.4 GB 81 GB

Sentinel‐1(TOPS (IW) mode)

170x250 km ~14x5 m  6 days 4.1 GB 246 GB

19‐Sep‐18

3

5EUREF 2018

2 Interferometric processing

Image reading

Image co‐registration

Image resampling

Interferogram formation

Reference phase 

subtraction (Ellipsoid, DEM)

(Phase unwrapping/

ambiguity resolution)

6EUREF 2018

Based on:• Image matching techniques, or• Geometric relations (precise satellite orbits, DEM, image

timing parameters)

Required precision:• 0.1 pixel (Stripmap mode)• 0.001 pixel (TOPS mode (Sentinel-1))

2 Interferometric processing

Image reading

Image co‐registration

Image resampling

Interferogram formation

Reference phase 

subtraction (Ellipsoid, DEM)

(Phase unwrapping/

ambiguity resolution)

19‐Sep‐18

4

7EUREF 2018

2 Interferometric processing

Image reading

Image co‐registration

Image resampling

Interferogram formation

Reference phase 

subtraction (Ellipsoid, DEM)

(Phase unwrapping/

ambiguity resolution)

8EUREF 2018

2 Interferometric processingSoftware

Open source software, e.g.

• DORIS (TU Delft, NL)

• SNAP toolbox (ESA)

• GMTSAR (Scripps Institution of Oceanography, USA)

Commercial software, e.g.

• GAMMA (GAMMA Remote Sensing, CH)

• SARScape (SARmap, CH)

19‐Sep‐18

5

9EUREF 2018

10EUREF 2018

3 Time series analysis

Initial point selectionFirst‐order network 

estimationAtmospheric phase screen estimation

Densification

19‐Sep‐18

6

11EUREF 2018

3 Time series analysis

Initial point selectionFirst‐order network 

estimationAtmospheric phase screen estimation

Densification

?Detection

Estimation

12EUREF 2018

3 Time series analysis

• Based on radar intensity consistency

• Typically 3-5 pts/km2

Initial point selectionFirst‐order network 

estimationAtmospheric phase screen estimation

Densification

19‐Sep‐18

7

13EUREF 2018

3 Time series analysis

• Typically 3-5 pts/km2

• Ambiguity resolution and parameter estimation based on spatial and/or temporal smoothness, e.g., linear deformation rates

Initial point selectionFirst‐order network 

estimationAtmospheric phase screen estimation

Densification

14EUREF 2018

3 Time series analysis

• Estimation of differential tropospheric and ionospheric signal delay

Initial point selectionFirst‐order network 

estimationAtmospheric phase screen estimation

Densification

19‐Sep‐18

8

15EUREF 2018

3 Time series analysis

In urban areas, typically • 1000 pts/km2 for medium-

resolution data• 10000 pts/km2 for high-

resolution data

Corresponding to max ~10% of original number of pixels.

Initial point selectionFirst‐order network 

estimationAtmospheric phase screen estimation

Densification

16EUREF 2018

3 Time series analysisSoftware

Open source software, e.g.

• StaMPS (Leeds, UK)

Commercial software, e.g.

• GAMMA (GAMMA Remote Sensing, CH)

• SARScape (SARmap, CH)

19‐Sep‐18

9

17EUREF 2018

4 Post-processing

E.g.,

• Georeferencing

• Point classification

• Separation deformation regimes

• Creation derived products (e.g., data gridding)

18EUREF 2018