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Thread: Producing a proper world map (globe)

  1. #11
      Thorf is offline
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    Iggy, I think perhaps what you need is a little knowledge of projections and distortion. What are the dimensions of your current map? In many ways the easiest projection to work in is the equirectangular, which is just a regular grid of squares with latitude and longitude plotted on them like a graph. This projection uses a 2:1 image, for example 6000 x 3000 pixels, and it's perfect for using as an overlay in Google Earth so you can see how things "really" look on your spherical world.

    The next step is to read up about and play with the distortion. Basically, there is no perfect projection of a sphere - all projections distort something, and in fact most projections only preserve one or at most two aspects of the following: shape, area, distance and direction. Some preserve none of these aspects, instead choosing to compromise.

    What you need to know about equirectangular maps is that they preserve distance along the equator and along all meridians (north-south), but east-west distances away from the equator are progressively more and more stretched, until the poles are represented by lines the entire width of the map. You can clearly see how this works if you overlay your map on Google Earth.

    The approach I have taken with this in my world maps is to start off with an equirectangular map, then reproject it using G.Projector to do both poles, as well as any other region I want an exact shape with. Specifically, if you reproject into equirectangular oblique centred on your area of interest, then do your design, and finally reproject back to equirectangular and update your original map, you should end up with a good base map. G.Projector is a bit fiddle in this regard, but it does work.

    The final step of course is to choose whatever projection you like best to present your world map in. It's important to remember that no one projection will do everything you want it to. Also, you should realise that large scales (local) are inherently less distorted than small scales (regional and world). If you want to do measurements, it may well be better to make several large scale maps of important areas.

  2. #12
      Iggy is offline
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    This is the current map I'm working on, it's 6000x3000 pixels, up scaled from 2000x1000 pixels before, no projection so far. I think my problem is that I understand the process you describe, not how you carry it out.

    I couldn't find the Photoshop plug in that I mentioned in my previous post so that one is out.
    Last edited by Iggy; 09-06-2013 at 02:59 PM.

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      Azelor is offline
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    Just to be clear, your map as it is right now uses a projection. No projection would mean that your map have the shape of a globe and is rendered in 3D. Projections exist so we can show Earth on a flat piece of paper wich is more useful but lee accurate than a globe. So doing a rectangular map mean you used a projection, even if you were not aware of it.

    If you want no projection, my guess would be that you use a 3D software to create a sphere and then paint on that sphere. Maybe PS6 can handle it, I have no idea.

    Maybe I just repeated what the others said but I am not sure to understand what is not working.
    Last edited by Azelor; 09-06-2013 at 03:57 PM.

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      waldronate is offline
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    If you can identify some points on the map and corresponding latitudes, folks here should be able to recommend a projection and/or process that might be helpful. Polar regions, for example, are best painted in a polar projection. Equatorial regions are generally good using a cylindrical projection. Regional maps might benefit from an azimuthal projection with its center of projection in the center of the map. Local maps are usually small enough that the distortion is minimal as long as the center of projection is in the center of the map.

    As always, it's a matter of what you're optimizing for (which differs with the type of map).

    I really, really need to spend a couple of weeks working on FT's brush tools to get useful dynamics and projective brushes. If only I had time and money...

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      Iggy is offline
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    I found out something that might be helpful. Photoshop CS6 Extended has 3D functionality through which I can create a sphere and paint directly on top of that. Here's how it looks. I haven't figured out how to sharpen the blurry lines of the grid and the sphere itself but what I have seen so far looks promising. I'm also curious if I can export the texture of the sphere as a flat image using a map projection type. To be continued.....

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    you really need to work with an equirectangular base map if youre going to be projecting it ontoa sphere, otherwise your poles are going to start looking kinda odd (to say the elast) once you wrap the skin around a globe

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      Iggy is offline
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    Quote Originally Posted by vorropohaiah View Post
    you really need to work with an equirectangular base map if youre going to be projecting it ontoa sphere, otherwise your poles are going to start looking kinda odd (to say the elast) once you wrap the skin around a globe
    How does one start with an equirectangular base map? (In Photoshop to be precise) Can I use my existing map or do I need to start from scratch? I loaded my map in G.Projector, applying the equirectangular projection had no effect. I think equirectangular projection is sufficient for my map.

    I've searched quite a bit on Google on this whole subject and I just can't find much that helps me further. Lots of tutorials on stuff but not what I was looking for.

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      Azelor is offline
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    If you can, you should export the spherical map into an equirectangular projection. But now that you have a globe, why would you want a flat map?

    You start an equirectangular projection by making the latitudes and longitudes lines always at the same distances. So you end up with a grid made of equal sized squares. Your map is already rectangular so do as Thorf said: keep a ratio of 2:1 ( the lenght is twice the height). That's prety much all there is to do.

  9. #19
      Iggy is offline
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    Quote Originally Posted by Azelor View Post
    If you can, you should export the spherical map into an equirectangular projection. But now that you have a globe, why would you want a flat map?
    Exactly my thought. I will continue to play with it and do some searching. if there's anything worth mentioning I'll post it.

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      Hai-Etlik is offline
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    Quote Originally Posted by Iggy View Post
    How does one start with an equirectangular base map? (In Photoshop to be precise) Can I use my existing map or do I need to start from scratch? I loaded my map in G.Projector, applying the equirectangular projection had no effect. I think equirectangular projection is sufficient for my map.

    I've searched quite a bit on Google on this whole subject and I just can't find much that helps me further. Lots of tutorials on stuff but not what I was looking for.
    It has no effect because G.Projector assumes that you are starting with that projection. The option is there so you can shift the standard parallels or to apply overlays. Of course if the map isn't in a normal aspect equirectangular/equidistant cylindrical projection to begin with, putting it though G.Projector isn't going to do anything to fix it.

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