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Last Post 23 Sep 2012 08:54 AM by  anon
ERS2 interferogram generation: ERS2 + orbital = failure
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anon



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23 Sep 2012 08:54 AM
    I'm having a problem when I try and create an interferogram (with DEM) using ERS2 and the precise orbits. Suprisingly, I can create an interferogram with the 2 generated SLC's when i don't use the precise orbital data during the focusing process. However, when I use precise orbital data it will focus the data without problem but when I try and form an interferogram it fails during the co-registration process and I get this error in the log (last few lines): Amplitude cross corr: NOT ENOUGHT POINTS FOUND FOR THE CO_REGISTRATION 18383) ) 18384) ) 18385) ) WARNING : WRONG IMAGES INCOMPATIBILITY [TOO FEW COREGISTRATION POINTS (CROSSCORR ERROR)] ((null)) 18386) ) CrossCorr-find fine shift from automatic windows grid [20020725_slc] SARscapeInSAR_DInSAR ENVI 4.3.000Jan 13 2011 18387) ) FILE=..\..\..\source\library\interf_utility\sars_cross_corr.cpp LINE=2580 (errno = 0)Error occour during first shift estimation form amplitude of class Cross-Corr in image: I:\ALL_DATA\ERS2\T40F2997\20020725_slc 18388) ) closing Master 18389) ) closing Slave 18390) ) (aTotLen + aLen) [38] 18391) ) (CSARS_MAX_LEN_IN_ERROR * CSARS_MAX_LINE_IN_ERROR) [144] 18392) ) 18393) ) ERROR : WRONG IMAGES INCOMPATIBILITY [CROSSCORR ERROR: WINDOW GRID] (I:\ALL_DATA\ERS2\T40F2997\20020725_slc) 18394) ) CrossCorr-find fine shift from automatic windows grid [20020725_slc] SARscapeInSAR_DInSAR ENVI 4.3.000Jan 13 2011 18395) ) FILE=..\..\..\source\library\interf_utility\sars_cross_corr.cpp LINE=10763 (errno = 0) 18396) ) I've loaded the ERS "ERS-ASAR_interferometry" settings before beginning interferogram generation. Like I said, I believe this has something to do with the precise orbital file used during the focusing because when I don't use them, I can generate the interferogram without issues. Any ideas? Thanks in advance.

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    23 Sep 2012 04:03 PM
    This has something to do with the orbital accuracy checkbox under the co-registration settings. When I don't check the box, the interferogram is generated. I'm just wondering by not selecting the check orbital accuracy, if the precise orbital data used during focusing will be used. Can anybody verify using focusing and interferogram generation for ERS2 using the precise orbital data (rev2) from ESA?

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    26 Sep 2012 01:41 PM
    During interferogram generation, you are using already focused data as input. So, if you uncheck the orbital accuracy box, that will not affect the focusing. Focusing will still have been performed using the precise orbital data. What happens, though, if you check the Orbital Accuracy option under Default Values > Coregistration, is that during the coregistration step, the accuracy of the coregistration polynomial will be checked against the precise orbital parameters. If you don't select Orbital Accuracy , then that check will not be made. If you would like to try to get this to run with the Orbital Accuracy option selected, then you might try the following: Change the following values under Default Values > Coregistration (and you might need to play around with even larger values if these don't work): Range Window Number 10 instead 6 Azimuth Window Number 15 instead 9 in CROSS CORRELATION GRID sub section Range Window Size 512 instead 256 Azimuth Window Size 1024 instead 512 In FINE SHIFT PARAMETERS sub section Range Window Number 40 instead 20 Azimuth Window Number 40 instead 20 I hope that helps. - Peg Exelis VIS Technical Support

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    04 Oct 2012 06:42 PM
    Ok. Thank you Peg! That does work better.
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