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Radar Course III
37. Bragg scattering
43. Texture and image analysis
42. Temporal averaging
12. Synthetic Aperture Radar (SAR)
34. Space, time and processing constraints
15. Slant range / ground range
8. Side-looking radars
19. Shadow
10. Real Aperture Radar: Range resolution
11. Real Aperture Radar: Azimuth resolution
9. Real Aperture Radar (RAR)
7. Radar principles
38. Radar image interpretation
35. The radar equation
36. Parameters affecting radar backscatter
16. Optical vs. microwave image geometry
25. Method
18. Layover
32. Landers Earthquake in South California
23. Introduction
27. Interferogramme of Naples (Italy)
29. Interferogramme and DEM of Gennargentu (Italy)
2. Independence of clouds coverage
40. Image interpretation: Speckle
41. Image interpretation: Speckle filters
39. Image interpretation: Tone
20. Geometric effects for image interpretation
22. Geocoding: Geometry
17. Foreshortening
26. First ERS-1/ERS-2 tandem interferogramme
6. Electromagnetic spectrum
30. Differential interferometry
45. Data reduction: 16 to 8 bit, blockaverage vs incrementing
4. Control of imaging geometry
3. Control of emitted electromagnetic radiation
24. Concept
28. Coherence image of Bonn area (Germany)
44. Classification of ERS-1 SAR images with Neural Networks
5. Access to different parameters compared to optical systems
13. SAR processing
33. SAR interferometric products
21. SAR image geocoding
14. ERS SAR geometric configuration
31. The Bonn experiment
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First ERS-1/ERS-2 tandem interferogramme

This image shows the interferometric phase obtained from the combination of an ERS-1 image taken on the 1st of May and the ERS-2 image taken exactly one day after, on the 2nd of May. It demonstrates the feasibility of the tandem mission.
An extract of the first ERS-2 image over the gulf of Gaeta in Central Italy was used in the generation of the coherence image. It contains an area of approximately 15 km by 20 km located in the far range of the original SAR image, just North of Gaeta.
The town of Terracina is located on the coast at the left of the interferogramme, while the village of Sperlonga can be seen on the coast on the right hand-side of the image.
In the plain in the middle of the image, one can see the lake of Fondi, which has taken its name from a town situated further into the plain.
The mountains surrounding the plain rise quite rapidly to heights between 800 metres and 1000 metres.
An interferogramme illustrates a technical complication associated with INSAR. The phase value (and hence phase differences) is not known absolutely, but is given in the range of 0-360º; i.e., the phase is "wrapped" on to a fixed range of angle. The colour contours cycle through a colour wheel corresponds to a complete rotation of 360º in phase.
In order to compute terrain height and generate a DEM, the interferogramme has to be "unwrapped", i.e., the correct multiple of 360º added to phase value of each pixel. A number of algorithms exist to perform this task.

(Rocca, POLIMI, Milano)

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry