page 1 envisat validation workshop - esrin – 9-13 december 2002 envisat validation workshop,...
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Page 1ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
ENVISAT Validation Workshop, Frascati, 9-13 December 2002
Hannes RaggamInstitute of Digital Image Processing,
Joanneum Research, Graz
Geometric Validation of PF-ASAR
IMP and IMM Products
Page 2ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
Test Procedures Applied to IMP and IMM
Import, format verificationVisual inspectionA-priori location accuracy through point residual
analysisEllipsoid geocoding:
Measure swath width IMM: Verify geometric continuity of multiple slices
Optional: Least squares parameter adjustment (a-posteriori
location accuracy) Geocoding, overlay of geocoded products
Page 3ENVISAT 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
Page 4ENVISAT 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)
Page 5ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
Flevopolder: A-Priori Location Accuracy
IMP products (preliminary):IMP products (preliminary):
Mean/Bias Std.Dev. Date Orbit Swath GCPs
East North East North
18/10/02 3311 IS7 / DSC 25 71.5 187.9 18.6 20.8 21/10/02 3354 IS5 / DSC 25 48.6 13.8 21.9 29.2 24/10/02 3397 IS4 / DSC 26 64.1 13.7 22.4 15.1 27/10/02 3447 IS5 / ASC 24 -33.4 -27.2 30.1 37.3 30/10/02 3490 IS6 / ASC 17 -46.8 -22.1 14.5 20.9 02/11/02 3526 IS1 / DSC 7 120.7 8.5 43.9 47.2 03/11/02 3540 IS7 / DSC 11 38.5 6.8 21.3 16.3 03/11/02 3547 IS1 / ASC 16 -102.1 -58.2 27.4 17.0
— Sign of bias (mean) correlates with flight direction: indication of systematic range (and azimuth) bias
— Results to be verified and cross-checked
Page 6ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
IMP - Orbit 3311 (18-Oct-2002)
Superposition of IMG (R) and ellipsoid geocoded IMP (G):Superposition of IMG (R) and ellipsoid geocoded IMP (G):
Page 7ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
IMP – A-priori Location Accuracy
3311 (R) – 3354 (G) – 3397 (B)3311 (R) – 3354 (G) – 3397 (B)
3354 (G) – 3397 (B)3354 (G) – 3397 (B)
Page 8ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
IMP – A-posteriori Location Accuracy
3311 (R) – 3354 (G) – 3397 (B)3311 (R) – 3354 (G) – 3397 (B)
A-prioriA-priori A-posterioriA-posteriori
— Least squares parameter adjustment (bias removal)
— Geocoding
Page 9ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
IMM – Algorithmic Issues
AzimuthAzimuth
Illu
min
atio
nIl
lum
inat
ion
— Multiple slices: imported as individual image products as well as merged product
Page 10ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
IMM – Algorithmic Issues
SR GR coefficients: Multiple SR GR records providing
SRGR coefficients for a given time Redundancy with Geolocation Grid
records (slant_range_times)
Page 11ENVISAT 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
44
33
2210
44
33
2210
rgbrgbrgbrgbbaz
rgargargargaars
rs..........slant range; az, rg....azimuth/range
coordinates
AzimuthAzimuthSRGR CoefficientsSRGR Coefficients Geolocation gridGeolocation grid
Page 12ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
Flevopolder: A-Priori Location Accuracy
IMM products (preliminary):IMM products (preliminary):
Mean/Bias Std.Dev. Date Orbit Swath GCPs
East North East North
18/10/02 3311 IS7 / DSC 20 118.7 63.4 87.7 64.6 21/10/02 3354 IS5 / DSC 17 90.9 50.7 57.0 43.1 24/10/02 3397 IS4 / DSC 23 126.3 0.1 85.7 37.8 27/10/02 3447 IS5 / ASC 19 -85.8 -115.6 93.0 83.3 30/10/02 3490 IS6 / ASC 16 -85.2 -74.4 63.3 52.0 02/11/02 3526 IS1 / DSC 13 261.9 -10.7 201.8 198.4 03/11/02 3540 IS7 / DSC 12 224.7 -2.7 287.9 87.5 03/11/02 3547 IS1 / ASC 22 -151.8 62.0 92.8 116.1
— Sign of bias (mean) correlates with flight direction: indication of systematic range bias
— Results to be verified and cross-checked
Page 13ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
IMM – Geocoded Image Slices
NN
Page 14ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
IMM – A-priori Geocoding Accuracy
3311 (R) – 3354 (G) – 3397 (B)3311 (R) – 3354 (G) – 3397 (B)
Page 15ENVISAT Validation Workshop - ESRIN – 9-13 December 2002
Summary of Results
Import, format verification o.k. Systematic range bias in IMP and IMM productsMultiple 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