Obtain the Map of horizontal gradient maxima derived from upward continuation at different heights

please I would like to know what are the different steps to get the card to obtain the Map of horizontal gradient maxima derived from upward continuation at different heights. For example this map:


  • BeckyBodger
    BeckyBodger Posts: 337 mod
    Hi @athanasekoumetio, Try using colour ranged symbols to display the different heights.

    1. Map Tools > Symbols > Colour Ranged Symbols
    2. Select the channel from your database that contains the different heights
    3. Select the number of heights to display
    4. Click the Ranges button to set the heights, and the Colours button to set the colours
    5. Click OK
    Community Manager

  • Thank's... bet , I have encountered some difficulties to start to know:
    - Should I first apply a horizontal gradient and / or upward continuation at different heights to the Bouguer anomaly (I use the gravimetric data), before launching with the steps so you have enumerated ???
    -If yes, at the question 2, in my database, I don't have the channel that contains the different heights. Indeed, when I apply upward continuation it generates me "grid" files that I can simply call in my window oasis. What to do I'm a little lost ???
  • BeckyBodger
    BeckyBodger Posts: 337 mod
    Technically speaking, you could calculate your horizontal gradient then upwards continue it to different heights, or upward continue the gravity data to different heights then calculate the horizontal gradient at each of those heights. I don't know which way would produce better results. You may have to try both and see what the differences are, or if one method works better than the other. Is there a paper that the image comes from? You may have to do some digging to see how it was created.

    If you have the results in multiple grids, you could save or sample the grids to a database before displaying your symbols.

    Sample a grid works if you have an existing database. It grabs the grid value at the XY locations from the database and stores the grid value in a new channel. You could try this with each of your grids at different heights, then you would have the horizontal gradient at different heights in separate channels in your database.

    Grid and Image > Utilities > Sample a grid.

    If you don't have an existing database, you can save the first grid to a data, which will create a new database with XY locations and a data channel. Then sample the other grids into this database to create the additional height channels.

    Grid and Image > Utilities > Save Grid to database.
    Community Manager

  • okay. thank's I will try again to see
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