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Thread: Finding a world map with an isostatic rebounded Antarctica

  1. #11
    Administrator waldronate's Avatar
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    Wilbur doesn't do arbitrary reprojections to equirectangular, that's more what ReprojectImage does. That looks pretty much like a Miller Cylindrical projection. ReprojectImage didn't do well with it, most likely because Reprojectimage was never intended as a high-accuracy tool (it's as good as you're willing to clumsily adjust things).

    Anyhow, here's what fell out (it's upside down, but I think that you can fix that):
    Click image for larger version. 

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  2. #12
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    Quote Originally Posted by waldronate View Post
    Alrighty, I downloaded that DEM and looked at it in Wilbur (it was handy and I'm familiar with it) and got this badly-cropped screenshot (the original image is 21600 pixels wide and this machine doesn't have much in the way of image handling software installed on it):
    Attachment 135303

    I was a little surprised to see less rebound in the Baltic areas the I had expected, but the Great Lakes in North America are pretty much gone, so that's good.

    Here are the Wilbur ( http://fracterra.com/software.html ) settings if you'd like to try it yourself:
    Attachment 135302
    How did you convert the original image into equirectangular within Wilbur?

  3. #13
    Administrator waldronate's Avatar
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    Quote Originally Posted by WoodytheClimateGuy View Post
    How did you convert the original image into equirectangular within Wilbur?
    I didn't convert anything. I downloaded the Digital Elevation Model (DEM) file https://ddfe.curtin.edu.au/models/Ea....1min.geod.bin from the author's website as I said above. That file is already in a special variant of the Equirectangular projection that has the cells equal in latitude and longitude ( https://en.wikipedia.org/wiki/Equire...lar_projection see the special case "geographic projection").

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    Quote Originally Posted by waldronate View Post
    I didn't convert anything. I downloaded the Digital Elevation Model (DEM) file https://ddfe.curtin.edu.au/models/Ea....1min.geod.bin from the author's website as I said above. That file is already in a special variant of the Equirectangular projection that has the cells equal in latitude and longitude ( https://en.wikipedia.org/wiki/Equire...lar_projection see the special case "geographic projection").
    Well, when I imported the bin file in Wilbur and used your settings, it turns out that the map looked like this. Solutions?

    Click image for larger version. 

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  5. #15
    Administrator waldronate's Avatar
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    That's the png file that accompanies the bin file on the author's web site. You can tell because it has all of the labels and stuff that's missing from the straight DEM (plus, Wilbur will never generate that color scheme unless you go to a lot of effort to enter it). The .bin file is 455MB in size, while the accompanying .png file you showed above is 850KB.

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    Sorry for not elaborating, but I was more referring to the projection of the map. It didn't have the standard equirectangular map, it had the projection shown in the image I showed while I imported the bin file into Wilbur. So, what did you do differently that caused you to have that equirectangular map?

  7. #17
    Administrator waldronate's Avatar
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    Use Surface>>Size with width 21800 and height 10800 to get a surface that's the size of the data set you want to import. You can use a smaller image if you want, but make sure to keep the 2:1 width:height ratio.

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    It ended up working! Thanks for that!

    However, I do have three questions.

    1. Keep the ratio in what area? Because 21800 is not twice as much as 10800. So, is the ratio there? Or is it in 21600 or 10800?
    2. How do you retain the colors? Because when saved it as a PNG, it lost the color, and it became black and white.
    3. If you are able to make the colors stay, can I change the color palette itself? Specifically in this image?

    Click image for larger version. 

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    And this is the color legend.

    Click image for larger version. 

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  9. #19
    Administrator waldronate's Avatar
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    To quote the great Barbara Millicent Roberts: "Math class is hard!" Yes, it should be 21600 wide and 10800 high as shown on the Wilbur dialog, not 21800 wide as I mistyped later.

    When saving as a PNG in Wilbur using File>>Save As, save it as a PNG Texture rather than a PNG Surface. Or, use Texture>>Save Texture As.

    Getting a precise palette in Wilbur is a little painful, but you should be able to use Shader Setup for the Wilbur shader, Set Absolute Coloring for Land and Sea, enter your desired minimum and maximum land altitude values, then the maximum (sea level) and minimum (Abs Min) values. Then Click Color List on the Land side and enter 10 colors, representing the 1000 foot intervals. Do the same for the Color List on the Sea side. I kept meaning to get around to making that easier to use, but I don't really use that feature very much anymore.

  10. #20
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    Great news, it worked! In addition, I'm using the map in my project!

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