DEM in small area

This topic contains 1 reply, has 2 voices, and was last updated by  periz 2 years, 5 months ago.

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  • #1942


    Hello Daniele,

    I am dealing with a geocoding problem. Everything seems fine, but the result is appr. 80 m shifted (and yes, the shift seems to be in the range direction). Tried many times to correct the geocoding, but the results did not change at all.

    I tried to display the DEM using DEM visualisation, and 3 of 4 tiles were missing (however, all four points were situated in the one tile present). OK, I deleted EDem.mat and redid everything, to see, that the results did not again change at all.

    So, is there a DEM matrix in the small area matfile? How to update it? When I do “load data”, I get “updating the SAR images only”… anything can be done else than reprocessing it all again? The pcodes version is quite old so I want to avoid it here.

    Or, do you have any other idea what could be wrong?

    Thank you very much, Ivana

  • #1943


    Hi Ivana,
    first, update the pcodes.
    Secondly, as repeated many times, you very seldom need to reprocess things (the only cases I’ve known of were about sentinel deramping, which is an operation that happens during coregisration. otherwise, if you data are well coregistered, no need to touch them).
    Third, in the small area module you can manually add a shift value in the height which should fix your matter.
    If you want anyway to check your dataset, you should plot the DEM in SAR coordinates (the external DEM height, plot it using the view parameters module in the site processing). check if values are correct and if it is well aligned with the refl map (plot also the synthetic amplitude).
    in the new pcodes version you can see many new things, you can also plot the DEM as background, to add one check more.
    Deleting the EDem.mat file probably was not a clever operation. Don’t delete files if you not sure about what you are doing.
    If you have still problems, we can check ur data together.

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