sarproz-group

Problem with GCP selection and Geocoding

This topic contains 6 replies, has 2 voices, and was last updated by  bala 2 months, 1 week ago.

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  • #2194

    bala
    Participant

    While I am doing GCP selection through “Keep current orbits” sometimes it’s giving zero value for Ext. DEM height and When I am doing this step through “Ext. DEM” GCP point is selected from out of the study area. In both cases, geocoding is not done perfectly. Here, I can’t select pixel by using “Force my pixel” option because of I am working with Glaciers. It’s very difficult to identify persistent pixel for this study area. Anyone, can give me suggestions for this problem?

    Regards,
    Bala

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  • #2202

    periz
    Keymaster

    hi Bala,
    the “force my pixel” option simply means that the software is not checking the probability that the pixel you selected is actually corresponding to a radar target. You can use it in the case of glaciers.
    Here the problem is the external DEM. When you say that the height is zero, I assume that there is no SRTM in your area. Is it correct? Do you have an other external DEM? If yes then you have to import it (e.g. make a geotiff file in geographic coordinates) and your problem is solved.
    If you have no external DEM, then your case would require to input manually the GCP height. This is disable by default but we can enable it for you. Let me know.

  • #2205

    bala
    Participant

    Dear Perissin,

    I tried with an external DEM but it’s not working. Could you please enable the option to give GCP height as manually?
    How can I give values through “Force my pixel” option? because for my study area it’s very difficult to match the GCP point (Lat and Lon) with the sample and line in Reflectivity map.

    Regards,
    Bala

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  • #2207

    periz
    Keymaster

    Can you be more specific about “you have tried with ext. DEM and it’s not working”? what did you do and what is not working? If you got errors, can you paste zipped lasterror.mat and log files?

  • #2208

    bala
    Participant

    Dear Perissin,

    First I processed with default (without using Ext.DEM) DEM, then I got GCP height as zero (Fig: Without Using Ext.DEM). After I used an Ext.DEM, then I got GCP height (Fig: With Ext.DEM) but it’s located at the out of selected study area (Master area) but inside the footprints. I continued the process, but the reflectivity map is generated out of the footprints (Fig: Reflectivity_map) and Geocoding is not done perfectly (Fig: Problem).

    Regards,
    Bala

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  • #2213

    periz
    Keymaster

    can you generate a higher resolution geocoded reflectivity map and send it to me by email?
    it could be correct and the footprint might be shifted.
    if this is the case, the reason is that footprints are geocoded using the elevation of a point in the middle of the area. You have steep mountains in your area, thus the footprint could be strongly shifted depending on where the center point falls (on a high or low elevation value…)

  • #2214

    bala
    Participant

    Dear Perissin,

    Can I use CoSSC products to generate Displacement map using SARPROZ? I want to use either TSX1_SAR_SSC data or TDX1_SAR_SSC data from 2 CoSSC products with 11 days temporal difference to Produce displacement, Is it possible to do with SARPROZ software?

    Best Regards,
    Bala

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