1. Page 1 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 ENVISAT Validation Workshop, Frascati, 9-13 December 2002 Hannes Raggam Institute of Digital Image Processing, Joanneum Research, Graz Geometric Validation of PF-ASAR IMP and IMM Products

2. Page 2 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 Test Procedures Applied to IMP and IMM Import, format verification Visual inspection A-priori location accuracy through point residual analysis Ellipsoid geocoding: u Measure swath width u IMM: Verify geometric continuity of multiple slices Optional: u Least squares parameter adjustment (a-posteriori location accuracy) u Geocoding, overlay of geocoded products

3. Page 3 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 Flevopolder - Ground Control — Pool of 49 control points measured in analogue maps 1:50.000 (Dutch stereographic projection, local Bessel ellipsoid) — Transformation to UTM, WGS84 datum, Zone 31

4. Page 4 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 A-priori Location Accuracy — Prediction of azimuth/range pixel coordinates and comparison with measurements  point residuals in image (pixel) — Intersection of SAR range circle with co-centric Earth ellipsoid at height of target point P  a-priori location error on ground (meters)

5. Page 5 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 Flevopolder: A-Priori Location Accuracy IMP products (preliminary): — Sign of bias (mean) correlates with flight direction: indication of systematic range (and azimuth) bias — Results to be verified and cross-checked

6. Page 6 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 IMP - Orbit 3311 (18-Oct-2002) Superposition of IMG (R) and ellipsoid geocoded IMP (G):

7. Page 7 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 IMP – A-priori Location Accuracy 3311 (R) – 3354 (G) – 3397 (B) 3354 (G) – 3397 (B)

8. Page 8 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 IMP – A-posteriori Location Accuracy 3311 (R) – 3354 (G) – 3397 (B) A-priori A-posteriori — Least squares parameter adjustment (bias removal) — Geocoding

9. Page 9 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 IMM – Algorithmic Issues Azimuth Illumination — Multiple slices: imported as individual image products as well as merged product

10. Page 10 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 IMM – Algorithmic Issues SR GR coefficients: u Multiple SR GR records providing SRGR coefficients for a given time u Redundancy with Geolocation Grid records (slant_range_times)

11. Page 11 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002......... IMM – Algorithmic Issues Establish continuous 2-dimensional function (polynomial) to determine slant range for given azimuth/range pixel values r s.......... slant range; az, rg.... azimuth/range coordinates Azimuth SRGR Coefficients Geolocation grid

12. Page 12 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 Flevopolder: A-Priori Location Accuracy IMM products (preliminary): — Sign of bias (mean) correlates with flight direction: indication of systematic range bias — Results to be verified and cross-checked

13. Page 13 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 IMM – Geocoded Image SlicesN

14. Page 14 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 IMM – A-priori Geocoding Accuracy 3311 (R) – 3354 (G) – 3397 (B)

15. Page 15 ENVISAT Validation Workshop - ESRIN – 9-13 December 2002 Summary of Results Import, format verification o.k. Systematic range bias in IMP and IMM products Multiple SRGR parameter updates supported (also in parameter adjustment) Accuracy (preliminary): in general a few pixels for IMP, sub-pixel for IMM feasible; to be further analyzed Tests to be completed, results to be verified and cross-checked with achievments from others Other test sites (also over hilly/mountaineous terrain) to be used