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Thread: Converting between map projections?

  1. #1
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    Default Converting between map projections?

    Hi all,

    I'm pretty new to mapmaking. I have followed the Salderan tutorial a couple of times, and quite like what I have managed using it, but I have a quick question.

    My world is very pole-centric, as the equator is hostile and essentially impassable (but not completely; that's the point of the story). So although I want to have a nice mercator or mollweide view of the planet, I would also like to be able to work on polar orthographic views (a round hemispheric view with with the pole in the middle and the equator at the edges).

    Now, something like FT3 would let me draw a map and switch between the projections, but drawing in FT3 and making the map look even remotely reasonable is tedious, especially if you are making a non-standard looking world (FT3 is great if you want to just end up with a randomly generated earthish planet, but not so great if you want to start with a blank world and draw it). Drawing in photoshop (using Saldferan or similar) is a lot easier, but you're stuck with the one projection you are working in.

    Is there an alternative? I thought about making a map in PS and importing it into FT, but it doesn't seem to allow importing. Is there any software that can take a map in one projection and allow you to view/save it in another, if you have drawn the map in a drawing program like PS?

    Thanks,
    Brian.

  2. #2
    Software Dev/Rep Gracious Donor waldronate's Avatar
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    There are many programs out there that can reproject an image. If you're using FT3, I recommend the following workflow (which is quite similar to Ralf Schemmann's old Jhendor tutorial at http://www.jhendor.de/tutorials/cc2-ft.pdf ):

    1) Use FT3 ( http://profantasy.com/to produce a polar aspect map grid at the resolution that you desire (e.g. Lambert Azimuthal Equal Area projection output to a 4kx4k PNG file Click image for larger version. 

Name:	LambertAzEqArea_Polar5deg.png 
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ID:	65034 ).
    2) Use this projection template as an overlay layer in Photoshop and paint your height map in the background. The extremely lazy among use might just rough it in and use something like the process described in http://www.cartographersguild.com/ma...und-lands.html to finalize things.
    3) Use ReprojectImage ( http://www.ridgenet.net/~jslayton/ReprojectImage.zip ) to reproject the world data to the equirectangular projection that FT expects as its binary input.
    4) Use Wilbur ( software ) to flip the image vertically and to convert the reprojected image into a .mdr file.
    5) Use FT3 and create a new world (File>>New) using the binary mdr file saved in Wilbur.

    If you just want to use a picture in FT3 but not height data, you can use the image overlays feature of FT3 to load the output of ReprojectImage directly.

  3. #3
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    Quote Originally Posted by waldronate View Post
    There are many programs out there that can reproject an image. If you're using FT3, I recommend the following workflow (which is quite similar to Ralf Schemmann's old Jhendor tutorial at http://www.jhendor.de/tutorials/cc2-ft.pdf ):
    Awesome, thanks for the reply!

    I will give this a go. I found g.projector last night from NASA, which is really good but it assumes you're starting with a rectangular mercator-type map; there doesn't seem to be any way of starting from a different projection, and I would rather start with an orthographic view and build from there, so your mini-tutorial looks to be just the ticket!

    Thanks again,
    Brian.

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