PI: Riccardo Lanari (IREA CNR)

Transcription

1 On the exploitation and validation of COSMO-SkyMed interferometric SAR data for digital terrain modelling and surface deformation analysis in extensive urban areas (ID: 1441) Project partners: Istituto di Metodologie per l'analisi Ambientale (IMAA CNR) Istituto per il Rilevamento Elettromagnetico dell'ambiente (IREA CNR) Istituto di Ricerca per la Protezione idrogeologica (IRPI CNR) Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS) DITS, Sapienza Universita' di Roma (UNIROMA1) Polo Regionale di Como, Politecnico di Milano (POLIMI) DITAG, Politecnico di Torino (POLITO) PI: Riccardo Lanari (IREA CNR) lanari.r@irea.cnr.it

2 Project objectives Exploitation of COSMO-Skymed (CSM) SAR constellation: for the analysis and validation of CSM DEM products (Objective 1) for surface deformation analysis over extensive urban areas (Objective 2)

3 Project Summary Project description and objectives Exploitation of COSMO-Skymed (CSM) SAR sensors: for the analysis and validation of CSM DEM products (Objective 1) for surface deformation analysis over extensive urban areas (Objective 2) Scientific Targets of the Project Objective 2 1 analysis investigation and validation of the capability of InSAR-based of the DInSAR CSM techniques DEMs by comparing applied to them CSM with reference data, in particular ones (particularly of the Small LIDAR). BAseline Subsequently Subset (SBAS) refocused approach, on radargrammetry; to reveal and monitor the temporal evolution of deformation phenomena affecting urbanized areas; DEM generation via fusion of different, given, DEMs with a comparable level of resolution and accuracy. analysis and validation of the computed CSM DInSAR products.

4 Test sites For DEM analysis and validation Como area Vesuvio area For SBAS-DInSAR analysis Colli Albani area Napoli area Roma area

5 CSM data availability For DEM analysis and validation 4 Spotlight images (2 asc+2 desc) on Como area Vesuvio area 1 Spotlight DEM of Colli Albani area For SBAS-DInSAR analysis 29 stripmap raw data (asc.) on Napoli area 21 stripmap raw data (asc.) on Roma area

6 CSM DEM catalogue product Spotlight COSMO-SkyMed DEM catalogue product (posting 3mx3m) relevant to the Colli Albani area (scene coverage 100Km 2 )

7 DEM analysis and validation: CSM vs SRTM N analysed points [m] bias [m] Comparison executed with software DEMANAL (developed by Prof. Jacobsen, Leibniz- University of Hannover)

8 DEM analysis and validation: CSM vs LIDAR N analysed points [m] bias [m] Comparison executed with software DEMANAL (developed by Prof. Jacobsen, Leibniz- University of Hannover)

9 Radargrammetry exploitation for DEM generation Radargrammetry: similar to photogrammetry; performs a 3D reconstruction based on the determination of the sensor-object stereo model, in which the object position is computed by the intersection of two radar rays with two different look angles Optimal geometric configurations: B/H ratio ranging from 0.25 to 2 is recommended to have a good stereo geometry Same-side to enable an easier image matching H B COSMO-SkyMed sensors operating in Spotlight mode (1 m resolution or better) can be well-suited for radargrammetry

10 vs P Radargrammetric model for SAR imagery ( P S ) 0 S D CS I S (zero-) Doppler equation (slant) range equation P position of a ground point P position of satellite S corresponding to the S point P satellite S velocity v S DS CS I near range slant range resolution (column spacing) column coordinate of the point P on the image In particular we have exploited the SISAR software previously developed by the Uniroma1 group. MEETING ASI COSMO-SkyMed Project 1441, March 2012, Roma

11 Radargrammetric CSM dataset on Como area Area Acquisition data Coverage (Km 2 ) Mean incidence angles (degrees) Orbit Look side B/H Como 24/6/ x Descending Right 28/6/ x Descending Right 17/6/ x Ascending Right 7/8/ x Ascending Right Spotlight imagery (azimuth slant range geometry) LiDAR Reference DSM

12 Radargrammetric DEM analysis and validation TILE 1 TILE 2 Because a descending and an ascending data pair was available, two different digital models have been generated. The radargrammetric DEMs have been compared in sample areas (TILE 1 and TILE 2, for instance) with a reference LIDAR one (through the DEMANAL software). The accuracy, in terms of RMSE, has been computed at the 95% probability level (LE95) in order to leave out the outliers from the statistical evaluation. MEETING ASI COSMO-SkyMed Project 1441, March 2012, Roma

13 Radargrammetric DEM analysis and validation (2) A third product has been created by the merging the two opposite side points clouds identified through the radargrammetric analysis. Merging Accuracy around 10 m Accuracy around 8 m Accuracy around 6-7 m DEM Descending DEM Ascending Merged DEM The achieved accuracy of the radargrammetric DEMs is remarkable, suggesting a more extensive exploitation of this kind of products. MEETING ASI COSMO-SkyMed Project 1441, March 2012, Roma

14 CSM exploitation for DInSAR analysis over urban areas For this task the activities have been mostly focused on: - investigating of the capability of the advanced DInSAR techniques applied to the CSM data, in particular of the Small BAseline Subset (SBAS) approach, to reveal and monitor the temporal evolution of deformation phenomena affecting urbanized areas; - the analysis and validation of the computed CSM DInSAR products. MEETING ASI COSMO-SkyMed Project 1441, March 2012, Roma

15 SBAS-DInSAR algorithm: key idea Small Baseline Interferograms For each coherent pixel of the interferograms the deformation time series is computed by searching for an LS solution with a minimum norm constraint. For more information refer to: Berardino, P., Fornaro, G., Lanari, R., Sansosti, E., A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms. IEEE Transactions on Geoscience and Remote Sensing 40 (11),

16 The Full Resolution SBAS approach Two-scale SBAS algorithm for CSM DInSAR processing Multi-look Interferogram Low Resolution Pixel Residual phase interferogram - + Single-look Interferogram MODEL Full Resolution Pixel ( HP) 4 b j z j r sin 4 ( HP ) ( T j ) v 2 ( HP) j x vs 4 ( HP) T j n j

17 CSM data: Doppler Centroid/Time distribution The doppler centroid offsets have been exploited to improve the geolocalization of the detected coherent pixels.

18 Geocoding without topography and azimuthal correction

19 Geocoding with topography and azimuthal correction

20 CSM baseline distribution: Napoli area 29 images

21 CSM baseline distribution: Napoli area 104 interferograms

22 CSM mean deformation velocity map: Napoli area CAMPI FLEGREI CALDERA >5 cm/yr VESUVIO NAPOLI <-5

23 Accuracy assessment of SBAS-DInSAR results: Napoli area > 3 Mean velocity [cm/yr] < - 3

24 Accuracy assessment of SBAS-DInSAR results: Napoli area (2) > 3 Mean velocity [cm/yr] < - 3

25 CSM/ENVISAT Comparison: Napoli area ENVISAT Mean velocity [cm/yr] > 1.0 < - 1.0

26 CSM/ENVISAT Comparison: Napoli area (2) > 5 CSM Mean velocity [mm/yr] < - 5 More than 6500 coherent pixels per squared km have been identified (more than 5 times better than ENVISAT).

27 CSM full resolution SBAS-DInSAR results: Napoli area Mean velocity [cm/yr] >3 <-3 <-3

28 CSM baseline distribution: Roma area 21 images

29 CSM baseline distribution: Roma area 21 images & 57 interferograms

30 CSM mean deformation velocity map: Roma area cm/yr >5 FIUMICINO AIRPORT ROMA <-5

31 COSMO SKYMED RESOLUTION - FIUMICINO CSM mean LOW deformation Fiumicino velocity Area map: Roma area FCO Airport Highway RM FCO cm/yr >5 <-5

32 TORRINO CSM/ENVISAT COSMO SKYMED Comparison: FULL Roma RESOLUTION area CSM The coherent pixel density increase for the CSM results is consistent with what already shown for the Napoli area. ENVISAT

33 CSM baseline distribution: Napoli area!

34 CSM baseline distribution: Roma area! The baseline dispersion should be corrected!

35 Thanks!!!